incubator-nuttx

History

Gregory Nutt 3a4984a40b Rename file_close_detached() to juse file_close() for better consistency in naming.		2018-09-15 13:04:56 -06:00
..
bridge	configs/: Refresh ARM and Xtensa configurations.	2018-08-19 17:48:13 -06:00
include	configs/*/include; Remove prototype of xyz_boardinitialize() from board.h files. The authorative prototype is in arch/arm/src/xyz/xyz_start.h	2017-12-16 20:47:44 -06:00
nsh	configs/: Refresh ARM and Xtensa configurations.	2018-08-19 17:48:13 -06:00
scripts	configs/: Add definition of strip to many Make.defs files.	2018-03-25 09:25:37 -06:00
src	Rename file_close_detached() to juse file_close() for better consistency in naming.	2018-09-15 13:04:56 -06:00
Kconfig	Remove the configs/ directory	2015-06-29 13:12:29 -06:00
README.txt	Remove CONFIG_ARCH_CALIBRATION. It is awkward to use and no longer necessary now that we have apps/examples/calib_udelay.	2018-08-19 10:06:36 -06:00

README.txt

README
======

This README file describes the port of NuttX to the SAMA5D3-Xplained
development board. This board features the Atmel SAMA5D36 microprocessor.
See http://www.atmel.com/devices/sama5d36.aspx for further information.

PARAMETER SAMA5D36
------------------------- -------------
Pin Count 324
Max. Operating Frequency 536 MHz
CPU Cortex-A5
Max I/O Pins 160
Ext Interrupts 160
USB Transceiver 3
USB Speed Hi-Speed
USB Interface Host, Device
SPI 6
TWI (I2C) 3
UART 7
CAN 2
LIN 4
SSC 2
Ethernet 2
SD / eMMC 3
Graphic LCD Yes
Camera Interface Yes
ADC channels 12
ADC Resolution (bits) 12
ADC Speed (ksps) 1000
Resistive Touch Screen Yes
Crypto Engine AES/DES/
SHA/TRNG
SRAM (Kbytes) 128
External Bus Interface 1
DRAM Memory DDR2/LPDDR,
SDRAM/LPSDR
NAND Interface Yes
Temp. Range (deg C) -40 to 105
I/O Supply Class 1.8/3.3
Operating Voltage (Vcc) 1.08 to 1.32
FPU Yes
MPU / MMU No/Yes
Timers 6
Output Compare channels 6
Input Capture Channels 6
PWM Channels 4
32kHz RTC Yes
Packages LFBGA324_A

Contents
========

- Development Environment
- GNU Toolchain Options
- IDEs
- NuttX EABI "buildroot" Toolchain
- NXFLAT Toolchain
- Loading Code into SRAM with J-Link
- Writing to FLASH using SAM-BA
- Running NuttX from SDRAM
- Buttons and LEDs
- Serial Console
- Networking
- AT25 Serial FLASH
- HSMCI Card Slots
- Auto-Mounter
- USB Ports
- USB High-Speed Device
- USB High-Speed Host
- SDRAM Support
- NAND Support
- I2C Tool
- CAN Usage
- SAMA5 ADC Support
- SAMA5 PWM Support
- RTC
- Watchdog Timer
- TRNG and /dev/random
- Tickless OS
- I2S Audio Support
- Shields
- SAMA5D3-Xplained Configuration Options
- Configurations
- To-Do List

Development Environment
=======================

Several possible development environments may be used:

- Linux or macOS native
- Cygwin unders Windows
- MinGW + MSYS under Windows
- Windows native (with GNUMake from GNUWin32).

All testing has been performed using Cygwin under Windows.

The source has been built only using the GNU toolchain (see below). Other
toolchains will likely cause problems.

GNU Toolchain Options
=====================

The NuttX make system will support the several different toolchain options.

All testing has been conducted using the CodeSourcery GCC toolchain. To use
a different toolchain, you simply need to add change to one of the following
configuration options to your .config (or defconfig) file:

CONFIG_ARMV7A_TOOLCHAIN_CODESOURCERYW=y : CodeSourcery under Windows
CONFIG_ARMV7A_TOOLCHAIN_CODESOURCERYL=y : CodeSourcery under Linux
CONFIG_ARMV7A_TOOLCHAIN_ATOLLIC=y : Atollic toolchain for Windos
CONFIG_ARMV7A_TOOLCHAIN_DEVKITARM=y : devkitARM under Windows
CONFIG_ARMV7A_TOOLCHAIN_BUILDROOT=y : NuttX buildroot under Linux or Cygwin (default)
CONFIG_ARMV7A_TOOLCHAIN_GNU_EABIL=y : Generic GCC ARM EABI toolchain for Linux
CONFIG_ARMV7A_TOOLCHAIN_GNU_EABIW=y : Generic GCC ARM EABI toolchain for Windows

The CodeSourcery GCC toolchain is selected with
CONFIG_ARMV7A_TOOLCHAIN_CODESOURCERYW=y and setting the PATH variable
appropriately.

NOTE about Windows native toolchains
------------------------------------

There are several limitations to using a Windows based toolchain in a
Cygwin environment. The three biggest are:

1. The Windows toolchain cannot follow Cygwin paths. Path conversions are
performed automatically in the Cygwin makefiles using the 'cygpath'
utility but you might easily find some new path problems. If so, check
out 'cygpath -w'

2. Windows toolchains cannot follow Cygwin symbolic links. Many symbolic
links are used in Nuttx (e.g., include/arch). The make system works
around these problems for the Windows tools by copying directories
instead of linking them. But this can also cause some confusion for
you: For example, you may edit a file in a "linked" directory and find
that your changes had no effect. That is because you are building the
copy of the file in the "fake" symbolic directory. If you use a\
Windows toolchain, you should get in the habit of making like this:

make clean_context all

An alias in your .bashrc file might make that less painful.

IDEs
====

NuttX is built using command-line make. It can be used with an IDE, but some
effort will be required to create the project.

Makefile Build
--------------
Under Eclipse, it is pretty easy to set up an "empty makefile project" and
simply use the NuttX makefile to build the system. That is almost for free
under Linux. Under Windows, you will need to set up the "Cygwin GCC" empty
makefile project in order to work with Windows (Google for "Eclipse Cygwin" -
there is a lot of help on the internet).

Native Build
------------
Here are a few tips before you start that effort:

1) Select the toolchain that you will be using in your .config file
2) Start the NuttX build at least one time from the Cygwin command line
before trying to create your project. This is necessary to create
certain auto-generated files and directories that will be needed.
3) Set up include pathes: You will need include/, arch/arm/src/sam34,
arch/arm/src/common, arch/arm/src/armv7-m, and sched/.
4) All assembly files need to have the definition option -D __ASSEMBLY__
on the command line.

Startup files will probably cause you some headaches. The NuttX startup file
is arch/arm/src/sam34/sam_vectors.S. You may need to build NuttX
one time from the Cygwin command line in order to obtain the pre-built
startup object needed by an IDE.

NuttX EABI "buildroot" Toolchain
================================

A GNU GCC-based toolchain is assumed. The PATH environment variable should
be modified to point to the correct path to the Cortex-M3 GCC toolchain (if
different from the default in your PATH variable).

If you have no Cortex-M3 toolchain, one can be downloaded from the NuttX
Bitbucket download site (https://bitbucket.org/nuttx/buildroot/downloads/).
This GNU toolchain builds and executes in the Linux or Cygwin environment.

1. You must have already configured Nuttx in <some-dir>/nuttx.

tools/configure.sh sama5d3-xplained/<sub-dir>

2. Download the latest buildroot package into <some-dir>

3. unpack the buildroot tarball. The resulting directory may
have versioning information on it like buildroot-x.y.z. If so,
rename <some-dir>/buildroot-x.y.z to <some-dir>/buildroot.

4. cd <some-dir>/buildroot

5. Copy the configuration file from the configs/ sub-directory to the
top-level build directory:

cp configs/cortexa8-eabi-defconfig-4.8.2 .config

6a. You may wish to modify the configuration before you build it. For
example, it is recommended that you build the kconfig-frontends tools,
generomfs, and the NXFLAT tools as well. You may also want to change
the selected toolchain. These reconfigurations can all be done with

make menuconfig

6b. If you chose to make the configuration with no changes, then you
should still do the following to make certain that the build
configuration is up-to-date:

make oldconfig

7. make

8. Make sure that the PATH variable includes the path to the newly built
binaries.

See the file configs/README.txt in the buildroot source tree. That has more
details PLUS some special instructions that you will need to follow if you are
building a Cortex-M3 toolchain for Cygwin under Windows.

NXFLAT Toolchain
================

If you are *not* using the NuttX buildroot toolchain and you want to use
the NXFLAT tools, then you will still have to build a portion of the buildroot
tools -- just the NXFLAT tools. The buildroot with the NXFLAT tools can
be downloaded from the NuttX Bitbucket download site
(https://bitbucket.org/nuttx/nuttx/downloads/).

This GNU toolchain builds and executes in the Linux or Cygwin environment.

1. You must have already configured Nuttx in <some-dir>/nuttx.

tools/configure.sh sama5d3-xplained/<sub-dir>

2. Download the latest buildroot package into <some-dir>

3. unpack the buildroot tarball. The resulting directory may
have versioning information on it like buildroot-x.y.z. If so,
rename <some-dir>/buildroot-x.y.z to <some-dir>/buildroot.

4. cd <some-dir>/buildroot

5. cp configs/cortexm3-defconfig-nxflat .config

6. make oldconfig

7. make

8. Make sure that the PATH variable includes the path to the newly built
NXFLAT binaries.

NOTE: There are some known incompatibilities with 4.6.3 EABI toolchain
and the NXFLAT tools. See the top-level TODO file (under "Binary
loaders") for more information about this problem. If you plan to use
NXFLAT, please do not use the GCC 4.6.3 EABI toochain.

Loading Code into SRAM with J-Link
==================================

Loading code with the Segger tools and GDB
------------------------------------------

1) Change directories into the directory where you built NuttX.
2) Start the GDB server and wait until it is ready to accept GDB
connections.
3) Then run GDB like this:

$ arm-none-eabi-gdb
(gdb) target remote localhost:2331
(gdb) mon reset
(gdb) load nuttx
(gdb) ... start debugging ...

Loading code using J-Link Commander
----------------------------------

J-Link> r
J-Link> loadbin <file> <address>
J-Link> setpc <address of __start>
J-Link> ... start debugging ...

Writing to FLASH using SAM-BA
=============================

Assumed starting configuration:

1. You have installed the J-Link CDC USB driver (Windows only, there is
no need to install a driver on any regular Linux distribution),
2. You have the USB connected to DBGU port (J23)
3. Terminal configuration: 115200 8N1

Using SAM-BA to write to FLASH:

1. Exit the terminal emulation program and remove the USB cable from
the DBGU port (J23)
2. Connect the USB cable to the device USB port (J6)
3. JP9 must open (BMS == 1) to boot from on-chip Boot ROM.
4. Press and maintain PB4 CS_BOOT button and power up the board. PB4
CS_BOOT button prevents booting from Nand or serial Flash by
disabling Flash Chip Selects after having powered the board, you can
release the PB4 BS_BOOT button.
5. On Windows you may need to wait for a device driver to be installed.
6. Start the SAM-BA application, selecting (1) the correct USB serial
port, and (2) board = at91sama5d3-xplained.
7. The SAM-BA menu should appear.
8. Select the FLASH bank that you want to use and the address to write
to and "Execute"
9. When you are finished writing to FLASH, remove the USB cable from J6
and re-connect the serial link on USB CDC / DBGU connector (J23) and
re-open the terminal emulator program.
10. Power cycle the board.

Running NuttX from SDRAM
========================

NuttX may be executed from SDRAM. But this case means that the NuttX
binary must reside on some other media (typically NAND FLASH, Serial
FLASH, or, perhaps even a TFTP server). In these cases, an intermediate
bootloader such as U-Boot or Barebox must be used to configure the
SAMA5D3 clocks and SDRAM and then to copy the NuttX binary into SDRAM.

- NuttX Configuration
- Boot sequence
- NAND FLASH Memory Map
- Programming the AT91Boostrap Binary
- Programming U-Boot
- Load NuttX with U-Boot on AT91 boards

TODO: Some drivers may require some adjustments to run from SDRAM. That
is because in this case macros like BOARD_MCK_FREQUENCY are not constants
but are instead function calls: The MCK clock frequency is not known in
advance but instead has to be calculated from the bootloader PLL configuration.
See the TODO list at the end of this file for further information.

NuttX Configuration
-------------------

In order to run from SDRAM, NuttX must be built at origin 0x20008000 in
SDRAM (skipping over SDRAM memory used by the bootloader). The following
configuration option is required:

CONFIG_SAMA5_BOOT_SDRAM=y
CONFIG_BOOT_RUNFROMSDRAM=y

These options tell the NuttX code that it will be booting and running from
SDRAM. In this case, the start-logic will do to things: (1) it will not
configure the SAMA5D3 clocking. Rather, it will use the clock configuration
as set up by the bootloader. And (2) it will not attempt to configure the
SDRAM. Since NuttX is already running from SDRAM, it must accept the SDRAM
configuration as set up by the bootloader.

Boot sequence
-------------

Reference: http://www.at91.com/linux4sam/bin/view/Linux4SAM/GettingStarted

Several pieces of software are involved to boot a Nutt5X into SDRAM. First
is the primary bootloader in ROM which is in charge to check if a valid
application is present on supported media (NOR FLASH, Serial DataFlash,
NAND FLASH, SD card).

The boot sequence of linux4SAM is done in several steps :

1. The ROM bootloader checks if a valid application is present in FLASH
and if it is the case downloads it into internal SRAM. This program
is usually a second level bootloader called AT91BootStrap.

2. AT91Bootstrap is the second level bootloader. It is in charge of the
hardware configuration. It downloads U-Boot / Barebox binary from
FLASH to SDRAM / DDRAM and starts the third level bootloader
(U-Boot / Barebox)

(see http://www.at91.com/linux4sam/bin/view/Linux4SAM/AT91Bootstrap).

3. The third level bootloader is either U-Boot or Barebox. The third
level bootloader is in charge of downloading NuttX binary from FLASH,
network, SD card, etc. It then starts NuttX.

4. Then NuttX runs from SDRAM

NAND FLASH Memory Map
---------------------

Reference: http://www.at91.com/linux4sam/bin/view/Linux4SAM/GettingStarted

0x0000:0000 - 0x0003:ffff: AT91BootStrap
0x0004:0000 - 0x000b:ffff: U-Boot
0x000c:0000 - 0x000f:ffff: U-Boot environment
0x0010:0000 - 0x0017:ffff: U-Boot environement redundant
0x0018:0000 - 0x001f:ffff: Device tree (DTB)
0x0020:0000 - 0x007f:ffff: NuttX
0x0080:0000 - end: Available for use as a NAND file system

Programming the AT91Boostrap Binary
-----------------------------------

Reference: http://www.at91.com/linux4sam/bin/view/Linux4SAM/AT91Bootstrap

This section describes how to program AT91Bootstrap binary into the boot
media with SAM-BA tool using NandFlash as boot media.

1. Get AT91BootStrap binaries. Build instructions are available here:

http://www.at91.com/linux4sam/bin/view/Linux4SAM/AT91Bootstrap#Build_AT91Bootstrap_from_sources

A pre-built AT91BootStrap binary is available here:

ftp://www.at91.com/pub/at91bootstrap/AT91Bootstrap3.6.1/sama5d3_xplained-nandflashboot-uboot-3.6.1.bin

2. Start the SAM-BA GUI Application:

- Connect the USB Device interface to your host machine using the USB
Device Cable.
- Make sure that the chip can execute the SAM-BA Monitor.
- Start SAM-BA GUI application.
- Select the board in the drop-down menu and choose the USB connection.

3. In the SAM-BA GUI Application:

- Choose the "NandFlash" tab in the SAM-BA GUI interface.
- Initialize the NandFlash by choosing the "Enable NandFlash" action in
the Scripts rolling menu, then press "Execute" button.
- Erase the NandFlash device by choosing the "Erase All" action, then
press "Execute" button.
- Enable the PMECC by choosing the "Enable OS PMECC parameters" action,
then press "Execute" button.

PMECC
Number of sectors per page: 4
Spare Size: 64
Number of ECC bits required: 4
Size of the ECC sector: 512
ECC offset: 36

- Choose "Send Boot File" action, then press Execute button to select the
at91bootstrap binary file and to program the binary to the NandFlash.
- Close SAM-BA, remove the USB Device cable.

Programming U-Boot
-------------------

Reference http://www.at91.com/linux4sam/bin/view/Linux4SAM/U-Boot

1. Get U-Boot Binaries. Build instructions are available here:

http://www.at91.com/linux4sam/bin/view/Linux4SAM/U-Boot#Build_U_Boot_from_sources

A pre-Built binary image is available here:

ftp://www.at91.com/pub/uboot/u-boot-v2013.07/u-boot-sama5d3_xplained-v2013.07-at91-r1.bin

2. Start the SAM-BA GUI Application:

3. In the SAM-BA GUI Application:

- Choose the NandFlash tab in the SAM-BA GUI interface.
- Initialize the NandFlash by choosing the "Enable NandFlash" action in
the Scripts rolling menu, then press Execute button.
- Enable the PMECC by choosing the "Enable OS PMECC parameters" action,
then press Execute button.

PMECC
Number of sectors per page: 4
Spare Size: 64
Number of ECC bits required: 4
Size of the ECC sector: 512
ECC offset: 36

- Press the "Send File Name" Browse button
- Choose u-boot.bin binary file and press Open
- Enter the proper address on media in the Address text field:
0x00040000
- Press the "Send File" button
- Close SAM-BA, remove the USB Device cable.

You should now be able to interrupt with U-Boot vie the DBGU interface.

Load NuttX with U-Boot on AT91 boards
-------------------------------------

Reference http://www.at91.com/linux4sam/bin/view/Linux4SAM/U-Boot

Preparing NuttX image

U-Boot does not support normal binary images. Instead you have to
create an uImage file with the mkimage tool which encapsulates kernel
image with header information, CRC32 checksum, etc.

mkimage comes in source code with U-Boot distribution and it is built
during U-Boot compilation (u-boot-source-dir/tools/mkimage). There
are also sites where you can download pre-built mkimage binaries. For
example: http://www.trimslice.com/wiki/index.php/U-Boot_images

See the U-Boot README file for more information. More information is
also available in the mkimage man page (for example,
http://linux.die.net/man/1/mkimage).

Command to generate an uncompressed uImage file (4) :

mkimage -A arm -O linux -C none -T kernel -a 20008000 -e 20008000 \
-n nuttx -d nuttx.bin uImage

Where:

-A arm: Set architecture to ARM
-O linux: Select operating system. bootm command of u-boot changes
boot method by os type.
-T kernel: Set image type.
-C none: Set compression type.
-a 20008000: Set load address.
-e 20008000: Set entry point.
-n nuttx: Set image name.
-d nuttx.bin: Use image data from nuttx.bin.

This will generate a binary called uImage. If you have the path to
mkimage in your PATH variable, then you can automatically build the
uImage file by adding the following to your .config file:

CONFIG_RAW_BINARY=y
CONFIG_UBOOT_UIMAGE=y
CONFIG_UIMAGE_LOAD_ADDRESS=0x20008000
CONFIG_UIMAGE_ENTRY_POINT=0x20008040

The uImage file can them be loaded into memory from a variety of sources
(serial, SD card, JFFS2 on NAND, TFTP).

STATUS:
2014-4-1: So far, I am unable to get U-Boot to execute the uImage
file. I get the following error messages (in this case
trying to load from an SD card):

U-Boot> fatload mmc 0 0x22000000 uimage
reading uimage
97744 bytes read in 21 ms (4.4 MiB/s)

U-Boot> bootm 0x22000000
## Booting kernel from Legacy Image at 0x22000000 ...
Image Name: nuttx
Image Type: ARM Linux Kernel Image (uncompressed)
Data Size: 97680 Bytes = 95.4 KiB
Load Address: 20008000
Entry Point: 20008040
Verifying Checksum ... OK
XIP Kernel Image ... OK
FDT and ATAGS support not compiled in - hanging
### ERROR ### Please RESET the board ###

This, however, appears to be a usable workaround:

U-Boot> fatload mmc 0 0x20008000 nuttx.bin
mci: setting clock 257812 Hz, block size 512
mci: setting clock 257812 Hz, block size 512
mci: setting clock 257812 Hz, block size 512
gen_atmel_mci: CMDR 00001048 ( 8) ARGR 000001aa (SR: 0c100025) Command Time Out
mci: setting clock 257812 Hz, block size 512
mci: setting clock 22000000 Hz, block size 512
reading nuttx.bin
108076 bytes read in 23 ms (4.5 MiB/s)

U-Boot> go 0x20008040
## Starting application at 0x20008040 ...

NuttShell (NSH) NuttX-7.2
nsh>

Loading through network

On a development system, it is useful to get the kernel and root file
system through the network. U-Boot provides support for loading
binaries from a remote host on the network using the TFTP protocol.

To manage to use TFTP with U-Boot, you will have to configure a TFTP
server on your host machine. Check your distribution manual or Internet
resources to configure a Linux or Windows TFTP server on your host:

- U-Boot documentation on a Linux host:
http://www.denx.de/wiki/view/DULG/SystemSetup#Section_4.6.

- Another TFTP configuration reference:
http://www.linuxhomenetworking.com/wiki/index.php/Quick_HOWTO_:_Ch16_:_Telnet%2C_TFTP%2C_and_xinetd#TFTP

On the U-Boot side, you will have to setup the networking parameters:

1. Setup an Ethernet address (MAC address)
Check this U-Boot network BuildRootFAQ entry to choose a proper MAC
address: http://www.denx.de/wiki/DULG/EthernetDoesNotWork

setenv ethaddr 00:e0:de:ad:be:ef

2. Setup IP parameters:
The board ip address

setenv ipaddr 10.0.0.2

The server ip address where the TFTP server is running

setenv serverip 10.0.0.1

3. saving Environment to flash

saveenv

4. If Ethernet Phy has not been detected during former bootup, reset
the board to reload U-Boot : the Ethernet address and Phy
initialization shall be ok, now

5. Download the NuttX uImage and the root file system to a ram location
using the U-Boot tftp command (Cf. U-Boot script capability chapter).

6. Launch NuttX issuing a bootm or boot command.

If the board has both emac and gmac, you can use following to choose
which one to use:

setenv ethact macb0,gmacb0
setenv ethprime gmacb0

STATUS:
2014-3-30: These instructions were adapted from the Linux4SAM website
but have not yet been used.

Using JTAG
----------

This description assumes that you have a JTAG debugger such as Segger
J-Link connected to the SAMA5D3-Xplained.

1. Start the GDB server
2. Start GDB
3. Use the 'target remote localhost:xxxx' command to attach to the GDG
server
4. Do 'mon reset' then 'mon go' to start the internal boot loader (maybe
U-Boot).
5. Let the boot loader run until it completes SDRAM initialization, then
do 'mon halt'.
6. Now you have SDRAM initialized and you use 'load nuttx' to load the
ELF file into SDRAM.
7. Use 'file nuttx' to load symbols
8. Set the PC to the NuttX entry point 'mon pc 0x20008040' and start
nuttx using 'mon go'.

Buttons and LEDs
================

Buttons
-------

The following push buttons switches are available:

1. One board reset button (BP2). When pressed and released, this push
button causes a power-on reset of the whole board.

2. One wakeup pushbutton that brings the processor out of Low-power mode
(BP1)

3. One user pushbutton (BP3)

Only the user push button (BP3) is controllable by software:

- PE29. Pressing the switch connect PE29 to ground. Therefore, PE29
must be pulled high internally. When the button is pressed the SAMA5
will sense "0" is on PE29.

LEDs
----
There are two LEDs on the SAMA5D3 series-CM board that can be controlled
by software. A blue LED is controlled via PIO pins. A red LED normally
provides an indication that power is supplied to the board but can also
be controlled via software.

PE23. This blue LED is pulled high and is illuminated by pulling PE23
low.

PE24. The red LED is also pulled high but is driven by a transistor so
that it is illuminated when power is applied even if PE24 is not
configured as an output. If PE24 is configured as an output, then the
LED is illuminated by a high output.

These LEDs are not used by the board port unless CONFIG_ARCH_LEDS is
defined. In that case, the usage by the board port is defined in
include/board.h and src/sam_leds.c. The LEDs are used to encode OS-related
events as follows:

SYMBOL Meaning LED state
Blue Red
------------------- ----------------------- -------- --------
LED_STARTED NuttX has been started OFF OFF
LED_HEAPALLOCATE Heap has been allocated OFF OFF
LED_IRQSENABLED Interrupts enabled OFF OFF
LED_STACKCREATED Idle stack created ON OFF
LED_INIRQ In an interrupt No change
LED_SIGNAL In a signal handler No change
LED_ASSERTION An assertion failed No change
LED_PANIC The system has crashed OFF Blinking
LED_IDLE MCU is is sleep mode Not used

Thus if the blue LED is statically on, NuttX has successfully booted and
is, apparently, running normally. If the red LED is flashing at
approximately 2Hz, then a fatal error has been detected and the system
has halted.

Serial Console
==============

UARTS/USARTS
------------

CONN LABEL PIO UART/USART FUNCTION
----- ------- ----- ----------- ---------------
J18 SCL0 PC30 UART0 UTXD0
J18 SDA0 PC29 UART0 URXD0
J15 1 PA31 UART1 UTXD1
J15 0 PA30 UART1 URXD1
J20 TXD3 14 PC26 UART1 URXD1
J20 RXD3 15 PC27 UART1 UTXD1
J20 TXD1 16 PD18 USART0 TXD0
J20 RXD1 17 PD17 USART0 RXD0
J20 TXD0 18 PB29 USART1 TXD1
J20 RXD0 19 PB28 USART1 RXD1
J20 SDA 20 PE19 USART3 TXD3
J20 SCL 21 PE18 USART3 RXD3

DBGU Interface
--------------

The SAMA5D3 Xplained board has a dedicated serial port for debugging,
which is accessible through the 6-pin male header J23.

PIN PIO Usage
--- ---- -----------------------------------------
1 PE13 (available)
2 PB31 DBGU DTXD
3 PB30 DBGU DRXD
4 N/C (may be used by debug interface tool)
5 PE14 (available)
6 GND

By default the DBUG port is used as the NuttX serial console in all
configurations (unless otherwise noted). The DBGU is available at
logic levels at pins RXD and TXD of the DEBUG connector (J23). GND
is available at J23 and +3.3V is available from J14

Networking
==========

Networking support via the can be added to NSH by selecting the following
configuration options. The SAMA5D36 supports two different Ethernet MAC
peripherals: (1) The 10/100Base-T EMAC peripheral and (2) the
10/100/1000Base-T GMAC peripheral.

Selecting the EMAC peripheral
-----------------------------

System Type -> SAMA5 Peripheral Support
CONFIG_SAMA5_EMACA=y : Enable the EMAC A peripheral

System Type -> EMAC device driver options
CONFIG_SAMA5_EMAC_NRXBUFFERS=16 : Set aside some RS and TX buffers
CONFIG_SAMA5_EMAC_NTXBUFFERS=4
CONFIG_SAMA5_EMAC_PHYADDR=1 : KSZ9031 PHY is at address 1
CONFIG_SAMA5_EMAC_AUTONEG=y : Use autonegotiation
CONFIG_SAMA5_EMAC_RMII=y : Either MII or RMII interface should work
CONFIG_SAMA5_EMAC_PHYSR=30 : Address of PHY status register on KSZ9031
CONFIG_SAMA5_EMAC_PHYSR_ALTCONFIG=y : Needed for KSZ9031
CONFIG_SAMA5_EMAC_PHYSR_ALTMODE=0x7 : " " " " " "
CONFIG_SAMA5_EMAC_PHYSR_10HD=0x1 : " " " " " "
CONFIG_SAMA5_EMAC_PHYSR_100HD=0x2 : " " " " " "
CONFIG_SAMA5_EMAC_PHYSR_10FD=0x5 : " " " " " "
CONFIG_SAMA5_EMAC_PHYSR_100FD=0x6 : " " " " " "

PHY selection. Later in the configuration steps, you will need to select
the KSZ9031 PHY for EMAC (See below)

Selecting the GMAC peripheral
-----------------------------

System Type -> SAMA5 Peripheral Support
CONFIG_SAMA5_GMAC=y : Enable the GMAC peripheral

System Type -> GMAC device driver options
CONFIG_SAMA5_GMAC_NRXBUFFERS=16 : Set aside some RS and TX buffers
CONFIG_SAMA5_GMAC_NTXBUFFERS=4
CONFIG_SAMA5_GMAC_PHYADDR=1 : KSZ8081 PHY is at address 1
CONFIG_SAMA5_GMAC_AUTONEG=y : Use autonegotiation

If both EMAC and GMAC are selected, you will also need:

CONFIG_SAMA5_GMAC_ISETH0=y : GMAC is "eth0"; EMAC is "eth1"

PHY selection. Later in the configuration steps, you will need to select
the KSZ9081 PHY for GMAC (See below)

Common configuration settings
-----------------------------

Networking Support
CONFIG_NET=y : Enable Neworking
CONFIG_NET_SOCKOPTS=y : Enable socket operations
CONFIG_NET_ETH_PKTSIZE=562 : Maximum packet size 1518 is more standard
CONFIG_NET_TCP=y : Enable TCP/IP networking
CONFIG_NET_TCPBACKLOG=y : Support TCP/IP backlog
CONFIG_NET_TCP_READAHEAD_BUFSIZE=562 : Read-ahead buffer size
CONFIG_NET_UDP=y : Enable UDP networking
CONFIG_NET_ICMP=y : Enable ICMP networking
CONFIG_NET_ICMP_SOCKET=y : Needed for NSH ping command
: Defaults should be okay for other options
Device drivers -> Network Device/PHY Support
CONFIG_NETDEVICES=y : Enabled PHY selection
CONFIG_ETH0_PHY_KSZ8081=y : Select the KSZ8081 PHY (for EMAC), OR
CONFIG_ETH0_PHY_KSZ90x1=y : Select the KSZ9031 PHY (for GMAC)

Application Configuration -> Network Utilities
CONFIG_NETDB_DNSCLIENT=y : Enable host address resolution
CONFIG_NETUTILS_TELNETD=y : Enable the Telnet daemon
CONFIG_NETUTILS_TFTPC=y : Enable TFTP data file transfers for get and put commands
CONFIG_NETUTILS_NETLIB=y : Network library support is needed
CONFIG_NETUTILS_WEBCLIENT=y : Needed for wget support
: Defaults should be okay for other options
Application Configuration -> NSH Library
CONFIG_NSH_TELNET=y : Enable NSH session via Telnet
CONFIG_NSH_IPADDR=0x0a000002 : Select an IP address
CONFIG_NSH_DRIPADDR=0x0a000001 : IP address of gateway/host PC
CONFIG_NSH_NETMASK=0xffffff00 : Netmask
CONFIG_NSH_NOMAC=y : Need to make up a bogus MAC address
: Defaults should be okay for other options

Using the network with NSH
--------------------------

So what can you do with this networking support? First you see that
NSH has several new network related commands:

ifconfig, ifdown, ifup: Commands to help manage your network
get and put: TFTP file transfers
wget: HTML file transfers
ping: Check for access to peers on the network
Telnet console: You can access the NSH remotely via telnet.

You can also enable other add on features like full FTP or a Web
Server or XML RPC and others. There are also other features that
you can enable like DHCP client (or server) or network name
resolution.

By default, the IP address of the SAMA5D3-Xplained will be 10.0.0.2 and
it will assume that your host is the gateway and has the IP address
10.0.0.1.

nsh> ifconfig
eth0 HWaddr 00:e0:de:ad:be:ef at UP
IPaddr:10.0.0.2 DRaddr:10.0.0.1 Mask:255.255.255.0

You can use ping to test for connectivity to the host (Careful,
Window firewalls usually block ping-related ICMP traffic). On the
target side, you can:

nsh> ping 10.0.0.1
PING 10.0.0.1 56 bytes of data
56 bytes from 10.0.0.1: icmp_seq=1 time=0 ms
56 bytes from 10.0.0.1: icmp_seq=2 time=0 ms
56 bytes from 10.0.0.1: icmp_seq=3 time=0 ms
56 bytes from 10.0.0.1: icmp_seq=4 time=0 ms
56 bytes from 10.0.0.1: icmp_seq=5 time=0 ms
56 bytes from 10.0.0.1: icmp_seq=6 time=0 ms
56 bytes from 10.0.0.1: icmp_seq=7 time=0 ms
56 bytes from 10.0.0.1: icmp_seq=8 time=0 ms
56 bytes from 10.0.0.1: icmp_seq=9 time=0 ms
56 bytes from 10.0.0.1: icmp_seq=10 time=0 ms
10 packets transmitted, 10 received, 0% packet loss, time 10100 ms

NOTE: In this configuration is is normal to have packet loss > 0%
the first time you ping due to the default handling of the ARP
table.

On the host side, you should also be able to ping the SAMA5D3-Xplained:

$ ping 10.0.0.2

You can also log into the NSH from the host PC like this:

$ telnet 10.0.0.2
Trying 10.0.0.2...
Connected to 10.0.0.2.
Escape character is '^]'.
sh_telnetmain: Session [3] Started

NuttShell (NSH) NuttX-6.31
nsh> help
help usage: help [-v] [<cmd>]

[ echo ifconfig mkdir mw sleep
? exec ifdown mkfatfs ping test
cat exit ifup mkfifo ps umount
cp free kill mkrd put usleep
cmp get losetup mh rm wget
dd help ls mount rmdir xd
df hexdump mb mv sh

Builtin Apps:
nsh>

NOTE: If you enable this feature, you experience a delay on booting.
That is because the start-up logic waits for the network connection
to be established before starting NuttX. In a real application, you
would probably want to do the network bringup on a separate thread
so that access to the NSH prompt is not delayed.

This delay will be especially long if the board is not connected to
a network. On the order of a minute! You will probably think that
NuttX has crashed! And then, when it finally does come up, the
network will not be available.

Network Initialization Thread
-----------------------------
There is a configuration option enabled by CONFIG_NSH_NETINIT_THREAD
that will do the NSH network bring-up asynchronously in parallel on
a separate thread. This eliminates the (visible) networking delay
altogether. This networking initialization feature by itself has
some limitations:

- If no network is connected, the network bring-up will fail and
the network initialization thread will simply exit. There are no
retries and no mechanism to know if the network initialization was
successful.

- Furthermore, there is no support for detecting loss of the network
connection and recovery of networking when the connection is restored.

Both of these shortcomings can be eliminated by enabling the network
monitor:

Network Monitor
---------------
By default the network initialization thread will bring-up the network
then exit, freeing all of the resources that it required. This is a
good behavior for systems with limited memory.

If the CONFIG_NSH_NETINIT_MONITOR option is selected, however, then the
network initialization thread will persist forever; it will monitor the
network status. In the event that the network goes down (for example, if
a cable is removed), then the thread will monitor the link status and
attempt to bring the network back up. In this case the resources
required for network initialization are never released.

Pre-requisites:

- CONFIG_NSH_NETINIT_THREAD as described above.

- CONFIG_NETDEV_PHY_IOCTL. Enable PHY IOCTL commands in the Ethernet
device driver. Special IOCTL commands must be provided by the Ethernet
driver to support certain PHY operations that will be needed for link
management. There operations are not complex and are implemented for
the Atmel SAMA5 family.

- CONFIG_ARCH_PHY_INTERRUPT. This is not a user selectable option.
Rather, it is set when you select a board that supports PHY interrupts.
In most architectures, the PHY interrupt is not associated with the
Ethernet driver at all. Rather, the PHY interrupt is provided via some
board-specific GPIO and the board-specific logic must provide support
for that GPIO interrupt. To do this, the board logic must do two things:
(1) It must provide the function arch_phy_irq() as described and
prototyped in the nuttx/include/nuttx/arch.h, and (2) it must select
CONFIG_ARCH_PHY_INTERRUPT in the board configuration file to advertise
that it supports arch_phy_irq(). This logic can be found at
nuttx/configs/sama5d3-xplained/src/sam_ethernet.c.

- And a few other things: UDP support is required (CONFIG_NET_UDP) and
signals must not be disabled (CONFIG_DISABLE_SIGNALS).

Given those prerequisites, the newtork monitor can be selected with these additional settings.

Networking Support -> Networking Device Support
CONFIG_NETDEV_PHY_IOCTL=y : Enable PHY ioctl support

Application Configuration -> NSH Library -> Networking Configuration
CONFIG_NSH_NETINIT_THREAD : Enable the network initialization thread
CONFIG_NSH_NETINIT_MONITOR=y : Enable the network monitor
CONFIG_NSH_NETINIT_RETRYMSEC=2000 : Configure the network monitor as you like
CONFIG_NSH_NETINIT_SIGNO=18

AT25 Serial FLASH
=================

Connections
-----------

The SAMA5D3-Xplained board supports an options Serial DataFlash connected
at MN8. The SPI connection is as follows:

MN8 SAMA5
------------- -----------------------------------------------
PIN FUNCTION PIO FUNCTION
--- --------- ----- -----------------------------------------
5 SI PD11 SPI0_MOSI
2 SO PD10 SPI0_MIS0
6 SCK PD12 SPI0_SPCK
1 /CS PD13 if jumper JP6 is closed.

NOTE: The MN8 is not populated on my SAMAD3 Xplained board. So, as a
result, these instructions would only apply if you were to have an AT25
Serial DataFlash installed in MN8.

Configuration
-------------

System Type -> SAMA5 Peripheral Support
CONFIG_SAMA5_SPI0=y : Enable SPI0
CONFIG_SAMA5_DMAC0=y : Enable DMA controller 0

System Type -> SPI device driver options
CONFIG_SAMA5_SPI_DMA=y : Use DMA for SPI transfers
CONFIG_SAMA5_SPI_DMATHRESHOLD=4 : Don't DMA for small transfers

Device Drivers -> SPI Driver Support
CONFIG_SPI=y : Enable SPI support
CONFIG_SPI_EXCHANGE=y : Support the exchange method

Device Drivers -> Memory Technology Device (MTD) Support
CONFIG_MTD=y : Enable MTD support
CONFIG_MTD_AT25=y : Enable the AT25 driver
CONFIG_AT25_SPIMODE=0 : Use SPI mode 0
CONFIG_AT25_SPIFREQUENCY=10000000 : Use SPI frequency 10MHz

The AT25 is capable of higher SPI rates than this. I have not experimented
a lot, but at 20MHz, the behavior is not the same with all CM modules. This
lower rate gives more predictable performance.

Application Configuration -> NSH Library
CONFIG_NSH_ARCHINIT=y : NSH board-initialization

Board Selection
CONFIG_SAMA5D3XPLAINED_AT25_AUTOMOUNT=y : Mounts AT25 for NSH
CONFIG_SAMA5D3XPLAINED_AT25_FTL=y : Create block driver for FAT

NOTE: that you must close JP6 in order to enable the AT25 FLASH chip select.

You can then format the AT25 FLASH for a FAT file system and mount the
file system at /mnt/at25 using these NSH commands:

nsh> mkfatfs /dev/mtdblock0
nsh> mount -t vfat /dev/mtdblock0 /mnt/at25

Then you an use the FLASH as a normal FAT file system:

nsh> echo "This is a test" >/mnt/at25/atest.txt
nsh> ls -l /mnt/at25
/mnt/at25:
-rw-rw-rw- 16 atest.txt
nsh> cat /mnt/at25/atest.txt
This is a test

HSMCI Card Slots
================

Physical Slots
--------------

The SAMA5D3-Xplained provides a two SD memory card slots: (1) a full size SD
card slot (J10), and (2) a microSD memory card slot (J11).

The full size SD card slot connects via HSMCI0. The card detect discrete
is available on PD17 (pulled high). The write protect discrete is tied to
ground and not i savailable to software. The slot supports 8-bit wide
transfer mode, but the NuttX driver currently uses only the 4-bit wide
transfer mode

PD17 MCI0_CD
PD1 MCI0_DA0
PD2 MCI0_DA1
PD3 MCI0_DA2
PD4 MCI0_DA3
PD5 MCI0_DA4
PD6 MCI0_DA5
PD7 MCI0_DA6
PD8 MCI0_DA7
PD9 MCI0_CK
PD0 MCI0_CDA

PE2 PWR_MCI0

The microSD connects vi HSMCI1. The card detect discrete is available on
PD18 (pulled high):

PD18 MCI1_CD
PB20 MCI1_DA0
PB21 MCI1_DA1
PB22 MCI1_DA2
PB23 MCI1_DA3
PB24 MCI1_CK
PB19 MCI1_CDA

Configuration Settings
----------------------

Enabling HSMCI support. The SAMA5D3-Xplained provides a two SD memory card
slots: (1) a full size SD card slot (J10), and (2) a microSD memory card
slot (J11). The full size SD card slot connects via HSMCI0; the microSD
connects via HSMCI1. Support for both SD slots can be enabled with the
following settings:

System Type->ATSAMA5 Peripheral Support
CONFIG_SAMA5_HSMCI0=y : Enable HSMCI0 support
CONFIG_SAMA5_HSMCI1=y : Enable HSMCI1 support
CONFIG_SAMA5_DMAC0=y : DMAC0 is needed by HSMCI0
CONFIG_SAMA5_DMAC1=y : DMAC1 is needed by HSMCI1

System Type
CONFIG_SAMA5_PIO_IRQ=y : PIO interrupts needed
CONFIG_SAMA5_PIOD_IRQ=y : Card detect pins are on PIOD

Device Drivers -> MMC/SD Driver Support
CONFIG_MMCSD=y : Enable MMC/SD support
CONFIG_MMSCD_NSLOTS=1 : One slot per driver instance
CONFIG_MMCSD_MULTIBLOCK_DISABLE=y : (REVISIT)
CONFIG_MMCSD_HAVE_CARDDETECT=y : Supports card-detect PIOs
CONFIG_MMCSD_MMCSUPPORT=n : Interferes with some SD cards
CONFIG_MMCSD_SPI=n : No SPI-based MMC/SD support
CONFIG_MMCSD_SDIO=y : SDIO-based MMC/SD support
CONFIG_SDIO_DMA=y : Use SDIO DMA
CONFIG_SDIO_BLOCKSETUP=y : Needs to know block sizes

Library Routines
CONFIG_SCHED_WORKQUEUE=y : Driver needs work queue support

Application Configuration -> NSH Library
CONFIG_NSH_ARCHINIT=y : NSH board-initialization

Using the SD card
-----------------

1) After booting, the HSCMI devices will appear as /dev/mmcsd0
and /dev/mmcsd1.

2) If you try mounting an SD card with nothing in the slot, the
mount will fail:

nsh> mount -t vfat /dev/mmcsd1 /mnt/sd1
nsh: mount: mount failed: 19

NSH can be configured to provide errors as strings instead of
numbers. But in this case, only the error number is reported. The
error numbers can be found in nuttx/include/errno.h:

#define ENODEV 19
#define ENODEV_STR "No such device"

So the mount command is saying that there is no device or, more
correctly, that there is no card in the SD card slot.

3) Inserted the SD card. Then the mount should succeed.

nsh> mount -t vfat /dev/mmcsd1 /mnt/sd1
nsh> ls /mnt/sd1
/mnt/sd1:
atest.txt
nsh> cat /mnt/sd1/atest.txt
This is a test

NOTE: See the next section entitled "Auto-Mounter" for another way
to mount your SD card.

4) Before removing the card, you must umount the file system. This is
equivalent to "ejecting" or "safely removing" the card on Windows: It
flushes any cached data to the card and makes the SD card unavailable
to the applications.

nsh> umount -t /mnt/sd1

It is now safe to remove the card. NuttX provides into callbacks
that can be used by an application to automatically unmount the
volume when it is removed. But those callbacks are not used in
these configurations.

Auto-Mounter
============

NuttX implements an auto-mounter than can make working with SD cards
easier. With the auto-mounter, the file system will be automatically
mounted when the SD card is inserted into the HSMCI slot and automatically
unmounted when the SD card is removed.

The auto-mounter is enable with:

CONFIG_FS_AUTOMOUNTER=y

However, to use the automounter you will to provide some additional
board-level support. See configs/sama5d4-ek for and example of how
you might do this.

WARNING: SD cards should never be removed without first unmounting
them. This is to avoid data and possible corruption of the file
system. Certainly this is the case if you are writing to the SD card
at the time of the removal. If you use the SD card for read-only access,
however, then I cannot think of any reason why removing the card without
mounting would be harmful.

USB Ports
=========

The SAMA5D3-Xplained features three USB communication ports:

* Port A Host High Speed (EHCI) and Full Speed (OHCI) multiplexed with
USB Device High Speed Micro AB connector, J6

* Port B Host High Speed (EHCI) and Full Speed (OHCI) standard type A
connector, J7 upper port

* Port C Host Full Speed (OHCI) only standard type A connector, J7
lower port

The two USB host ports (only) are equipped with 500-mA high-side power
switch for self-powered and bus-powered applications.

The USB device port A (J6) features a VBUS insert detection function.

Port A
------

PIO Signal Name Function
---- ----------- -------------------------------------------------------
PE9 VBUS_SENSE VBus detection

Note: No VBus power switch enable on port A. I think that this limits
this port to a device port or as a host port for self-powered devices
only.

Port B
------

PIO Signal Name Function
---- ----------- -------------------------------------------------------
PE4 EN5V_USBB VBus power enable (via MN3 power switch). To the A1
pin of J7 Dual USB A connector

Port C
------

PIO Signal Name Function
---- ----------- -------------------------------------------------------
PE3 EN5V_USBC VBus power enable (via MN3 power switch). To the B1
pin of J7 Dual USB A connector

Both Ports B and C
------------------

PIO Signal Name Function
---- ----------- -------------------------------------------------------
PE5 OVCUR_USB Combined over-current indication from port A and B

USB High-Speed Device
=====================

Basic USB High-Speed Device Configuration
-----------------------------------------

Support the USB high-speed device (UDPHS) driver can be enabled with these
NuttX configuration settings.

Device Drivers -> USB Device Driver Support
CONFIG_USBDEV=y : Enable USB device support
CONFIG_USBDEV_DUALSPEED=y : Device support High and Full Speed
CONFIG_USBDEV_DMA=y : Device uses DMA

System Type -> ATSAMA5 Peripheral Support
CONFIG_SAMA5_UDPHS=y : Enable UDPHS High Speed USB device

Application Configuration -> NSH Library
CONFIG_NSH_ARCHINIT=y : NSH board-initialization

Mass Storage Class
------------------

The Mass Storage Class (MSC) class driver is selected for use with
UDPHS:

Device Drivers -> USB Device Driver Support
CONFIG_USBMSC=y : Enable the USB MSC class driver
CONFIG_USBMSC_EPBULKOUT=1 : Use EP1 for the BULK OUT endpoint
CONFIG_USBMSC_EPBULKIN=2 : Use EP2 for the BULK IN endpoint

The following setting enables an add-on that can can be used to control
the USB MSC device. It will add two new NSH commands:

a. msconn will connect the USB serial device and export the AT25
to the host, and
b. msdis which will disconnect the USB serial device.

Application Configuration -> System Add-Ons:
CONFIG_SYSTEM_USBMSC=y : Enable the USBMSC add-on
CONFIG_SYSTEM_USBMSC_NLUNS=1 : One LUN
CONFIG_SYSTEM_USBMSC_DEVMINOR1=0 : Minor device zero
CONFIG_SYSTEM_USBMSC_DEVPATH1="/dev/mtdblock0"
: Use a single, LUN: The AT25
: block driver.

NOTES:

a. To prevent file system corruption, make sure that the AT25 is un-
mounted *before* exporting the mass storage device to the host:

nsh> umount /mnt/at25
nsh> mscon

The AT25 can be re-mounted after the mass storage class is disconnected:

nsh> msdis
nsh> mount -t vfat /dev/mtdblock0 /mnt/at25

b. If you change the value CONFIG_SYSTEM_USBMSC_DEVPATH1, then you
can export other file systems:

"/dev/mmcsd1" will export the HSMCI1 microSD
"/dev/mmcsd0" will export the HSMCI0 full-size SD slot
"/dev/ram0" could even be used to export a RAM disk. But you would
first have to use mkrd to create the RAM disk and mkfatfs to put
a FAT file system on it.

CDC/ACM Serial Device Class
---------------------------

This will select the CDC/ACM serial device. Defaults for the other
options should be okay.

Device Drivers -> USB Device Driver Support
CONFIG_CDCACM=y : Enable the CDC/ACM device
CONFIG_CDCACM_BULKIN_REQLEN=768 : Default too small for high-speed

The following setting enables an example that can can be used to control
the CDC/ACM device. It will add two new NSH commands:

a. sercon will connect the USB serial device (creating /dev/ttyACM0), and
b. serdis which will disconnect the USB serial device (destroying
/dev/ttyACM0).

Application Configuration -> Examples:
CONFIG_SYSTEM_CDCACM=y : Enable an CDC/ACM example

Debugging USB Device
--------------------

There is normal console debug output available that can be enabled with
CONFIG_DEBUG_FEATURES + CONFIG_DEBUG_USB. However, USB device operation is very
time critical and enabling this debug output WILL interfere with the
operation of the UDPHS. USB device tracing is a less invasive way to get
debug information: If tracing is enabled, the USB device will save
encoded trace output in in-memory buffer; if the USB monitor is also
enabled, that trace buffer will be periodically emptied and dumped to the
system logging device (the serial console in this configuration):

Device Drivers -> "USB Device Driver Support:
CONFIG_USBDEV_TRACE=y : Enable USB trace feature
CONFIG_USBDEV_TRACE_NRECORDS=256 : Buffer 256 records in memory
CONFIG_USBDEV_TRACE_STRINGS=y : (optional)

Application Configuration -> NSH LIbrary:
CONFIG_NSH_USBDEV_TRACE=n : No builtin tracing from NSH
CONFIG_NSH_ARCHINIT=y : Automatically start the USB monitor

Application Configuration -> System NSH Add-Ons:
CONFIG_USBMONITOR=y : Enable the USB monitor daemon
CONFIG_USBMONITOR_STACKSIZE=2048 : USB monitor daemon stack size
CONFIG_USBMONITOR_PRIORITY=50 : USB monitor daemon priority
CONFIG_USBMONITOR_INTERVAL=1 : Dump trace data every second
CONFIG_USBMONITOR_TRACEINIT=y : Enable TRACE output
CONFIG_USBMONITOR_TRACECLASS=y
CONFIG_USBMONITOR_TRACETRANSFERS=y
CONFIG_USBMONITOR_TRACECONTROLLER=y
CONFIG_USBMONITOR_TRACEINTERRUPTS=y

NOTE: If USB debug output is also enabled, both outputs will appear on the
serial console. However, the debug output will be asynchronous with the
trace output and, hence, difficult to interpret.

USB High-Speed Host
===================

OHCI Only
---------

Support the USB low/full-speed OHCI host driver can be enabled by changing
the NuttX configuration file as follows:

System Type -> ATSAMA5 Peripheral Support
CONFIG_SAMA5_UHPHS=y : USB Host High Speed

System Type -> USB High Speed Host driver options
CONFIG_SAMA5_OHCI=y : Low/full-speed OHCI support
: Defaults for values probably OK
Device Drivers
CONFIG_USBHOST=y : Enable USB host support

Device Drivers -> USB Host Driver Support
CONFIG_USBHOST_ISOC_DISABLE=y : Isochronous endpoints not used
CONFIG_USBHOST_MSC=y : Enable the mass storage class driver
CONFIG_USBHOST_HIDKBD=y : Enable the HID keyboard class driver

RTOS Features -> Work Queue Support
CONFIG_SCHED_WORKQUEUE=y : High priority worker thread support is required
CONFIG_SCHED_HPWORK=y :

Application Configuration -> NSH Library
CONFIG_NSH_ARCHINIT=y : NSH board-initialization
file1: CONFIG_USBHOST_ISOC_DISABLE=y

NOTE: When OHCI is selected, the SAMA5 will operate at 384MHz instead of
396MHz. This is so that the PLL generates a frequency which is a multiple
of the 48MHz needed for OHCI. The delay loop calibration values that are
used will be off slightly because of this.

EHCI
----

Support the USB high-speed EHCI host driver can be enabled by changing the
NuttX configuration file as follows. If EHCI is enabled by itself, then
only high-speed devices can be supported. If OHCI is also enabled, then
all low-, full-, and high speed devices will work.

System Type -> ATSAMA5 Peripheral Support
CONFIG_SAMA5_UHPHS=y : USB Host High Speed

System Type -> USB High Speed Host driver options
CONFIG_SAMA5_EHCI=y : High-speed EHCI support
CONFIG_SAMA5_OHCI=y : Low/full-speed OHCI support
: Defaults for values probably OK for both
Device Drivers
CONFIG_USBHOST=y : Enable USB host support
CONFIG_USBHOST_INT_DISABLE=y : Interrupt endpoints not needed
CONFIG_USBHOST_ISOC_DISABLE=y : Isochronous endpoints not needed

RTOS Features -> Work Queue Support
CONFIG_SCHED_WORKQUEUE=y : High priority worker thread support is required
CONFIG_SCHED_HPWORK=y :

Application Configuration -> NSH Library
CONFIG_NSH_ARCHINIT=y : NSH board-initialization

USB Hub Support
----------------

USB hub support can be included by adding the following changes to the configuration (in addition to those listed above):

Drivers -> USB Host Driver Support
CONFIG_USBHOST_HUB=y : Enable the hub class
CONFIG_USBHOST_ASYNCH=y : Asynchonous I/O supported needed for hubs

System Type -> USB High Speed Host driver options
CONFIG_SAMA5_OHCI_NEDS=12 : You will probably want more pipes
CONFIG_SAMA5_OHCI_NTDS=18
CONFIG_SAMA5_OHCI_TDBUFFERS=12
CONFIG_SAMA5_OHCI_TDBUFSIZE=128

Board Selection ->
CONFIG_SAMA5D3XPLAINED_USBHOST_STACKSIZE=2048 (bigger than it needs to be)

RTOS Features -> Work Queue Support
CONFIG_SCHED_LPWORK=y : Low priority queue support is needed
CONFIG_SCHED_LPNTHREADS=1
CONFIG_SCHED_LPWORKSTACKSIZE=1024

NOTES:

1. It is necessary to perform work on the low-priority work queue
(vs. the high priority work queue) because deferred hub-related
work requires some delays and waiting that is not appropriate on
the high priority work queue.

2. Stack usage make increase when USB hub support is enabled because
the nesting depth of certain USB host class logic can increase.

STATUS:
2015-05-01:
This USB host function does not work on the SAMA5D3-Xplained board.
Those same drivers work on the other SAMA5Dx boards and so I believe
that there is some issue with either clocking to USB or to powering
of the USB host ports.

Mass Storage Device Usage
-------------------------

Example Usage:

NuttShell (NSH) NuttX-6.29
nsh> ls /dev
/dev:
console
mtdblock0
null
ttyS0

Here a USB FLASH stick is inserted. Nothing visible happens in the
shell. But a new device will appear:

nsh> ls /dev
/dev:
console
mtdblock0
null
sda
ttyS0
nsh> mount -t vfat /dev/sda /mnt/sda
nsh> ls -l /mnt/sda
/mnt/sda:
-rw-rw-rw- 8788 viminfo
drw-rw-rw- 0 .Trash-1000/
-rw-rw-rw- 3378 zmodem.patch
-rw-rw-rw- 1503 sz-1.log
-rw-rw-rw- 613 .bashrc

HID Keyboard Usage
------------------

If a (supported) USB keyboard is connected, a /dev/kbda device will appear:

nsh> ls /dev
/dev:
console
kbda
mtdblock0
null
ttyS0

/dev/kbda is a read-only serial device. Reading from /dev/kbda will get
keyboard input as ASCII data (other encodings are possible):

nsh> cat /dev/kbda

Debugging USB Host
------------------

There is normal console debug output available that can be enabled with
CONFIG_DEBUG_FEATURES + CONFIG_DEBUG_USB. However, USB host operation is very time
critical and enabling this debug output might interfere with the operation
of the UDPHS. USB host tracing is a less invasive way to get debug
information: If tracing is enabled, the USB host will save encoded trace
output in in-memory buffer; if the USB monitor is also enabled, that trace
buffer will be periodically emptied and dumped to the system logging device
(the serial console in this configuration):

Device Drivers -> "USB Host Driver Support:
CONFIG_USBHOST_TRACE=y : Enable USB host trace feature
CONFIG_USBHOST_TRACE_NRECORDS=256 : Buffer 256 records in memory
CONFIG_USBHOST_TRACE_VERBOSE=y : Buffer everything

Application Configuration -> NSH LIbrary:
CONFIG_NSH_USBDEV_TRACE=n : No builtin tracing from NSH
CONFIG_NSH_ARCHINIT=y : Automatically start the USB monitor

NOTE: If USB debug output is also enabled, both outpus will appear on the
serial console. However, the debug output will be asynchronous with the
trace output and, hence, difficult to interpret.

SDRAM Support
=============

SRAM Heap Configuration
-----------------------

In these configurations, .data and .bss are retained in ISRAM. SDRAM can
be initialized and included in the heap. Relevant configuration settings:

System Type->ATSAMA5 Peripheral Support
CONFIG_SAMA5_MPDDRC=y : Enable the DDR controller

System Type->External Memory Configuration
CONFIG_SAMA5_DDRCS=y : Tell the system that DRAM is at the DDR CS
CONFIG_SAMA5_DDRCS_SIZE=268435456 : 2Gb DRAM -> 256MB
CONFIG_SAMA5_DDRCS_LPDDR2=y : Its DDR2
CONFIG_SAMA5D3XPLAINED_MT47H128M16RT=y : This is the type of DDR2

System Type->Heap Configuration
CONFIG_SAMA5_DDRCS_HEAP=y : Add the SDRAM to the heap
CONFIG_SAMA5_DDRCS_HEAP_OFFSET=0
CONFIG_SAMA5_DDRCS_HEAP_SIZE=268435456

Memory Management
CONFIG_MM_REGIONS=2 : Two heap memory regions: ISRAM and SDRAM

RAM Test
--------

Another thing you could do is to enable the RAM test built-in application.
You can enable the NuttX RAM test that may be used to verify the external
SDRAM. To do this, keep the SDRAM out of the heap so that it can be tested
without crashing programs using the memory:

System Type->Heap Configuration
CONFIG_SAMA5_DDRCS_HEAP=n : Don't add the SDRAM to the heap

Memory Management
CONFIG_MM_REGIONS=1 : One memory regions: ISRAM

Then enable the RAM test built-in application:

Application Configuration->System NSH Add-Ons->Ram Test
CONFIG_SYSTEM_RAMTEST=y

In this configuration, the SDRAM is not added to heap and so is not
accessable to the applications. So the RAM test can be freely executed
against the SRAM memory beginning at address 0x2000:0000 (DDR CS):

nsh> ramtest -h
Usage: <noname> [-w|h|b] <hex-address> <decimal-size>

Where:
<hex-address> starting address of the test.
<decimal-size> number of memory locations (in bytes).
-w Sets the width of a memory location to 32-bits.
-h Sets the width of a memory location to 16-bits (default).
-b Sets the width of a memory location to 8-bits.

To test the entire external 256MB SRAM:

nsh> ramtest -w 20000000 268435456
RAMTest: Marching ones: 20000000 268435456
RAMTest: Marching zeroes: 20000000 268435456
RAMTest: Pattern test: 20000000 268435456 55555555 aaaaaaaa
RAMTest: Pattern test: 20000000 268435456 66666666 99999999
RAMTest: Pattern test: 20000000 268435456 33333333 cccccccc
RAMTest: Address-in-address test: 20000000 268435456

SDRAM Data Configuration
------------------------

In these configurations, .data and .bss are retained in ISRAM by default.
.data and .bss can also be retained in SDRAM using these slightly
different configuration settings. In this configuration, ISRAM is
used only for the Cortex-A5 page table for the IDLE thread stack.

System Type->ATSAMA5 Peripheral Support
CONFIG_SAMA5_MPDDRC=y : Enable the DDR controller

System Type->External Memory Configuration
CONFIG_SAMA5_DDRCS=y : Tell the system that DRAM is at the DDR CS
CONFIG_SAMA5_DDRCS_SIZE=268435456 : 2Gb DRAM -> 256GB
CONFIG_SAMA5_DDRCS_LPDDR2=y : Its DDR2
CONFIG_SAMA5D3XPLAINED_MT47H128M16RT=y : This is the type of DDR2

System Type->Heap Configuration
CONFIG_SAMA5_ISRAM_HEAP=n : These do not apply in this case
CONFIG_SAMA5_DDRCS_HEAP=n

System Type->Boot Memory Configuration
CONFIG_RAM_START=0x20000000 : Physical address of SDRAM
CONFIG_RAM_VSTART=0x20000000 : Virtual address of SDRAM
CONFIG_RAM_SIZE=268435456 : Size of SDRAM
CONFIG_BOOT_SDRAM_DATA=y : Data is in SDRAM

Care must be used applied these RAM locations; graphics
configurations may use SDRAM in an incompatible way to set aside
LCD framebuffers.

Memory Management
CONFIG_MM_REGIONS=1 : One heap memory region: ISDRAM

NAND Support
============

NAND support is only partial in that there is no file system that works
with it properly. Lower-level NAND support has been developed and
verified, but there is no way to use it in the current NuttX architecture
other than through the raw MTD interface.

NAND should still be considered a work in progress. You will not want to
use NAND unless you are interested in investing a little effort,
particularly in infrastructure. See the "STATUS SUMMARY" section below.

NAND Support
------------

NAND Support can be added to the NSH configuration by modifying the
NuttX configuration file as follows:

Build Setup
CONFIG_EXPERIMENTAL=y : NXFFS implementation is incomplete and
: not yet fully functional.

System Type -> SAMA5 Peripheral support
CONFIG_SAMA5_HSMC=y : Make sure that the SMC is enabled

Drivers -> Memory Technology Device (MTD) Support
CONFIG_MTD=y : Enable MTD support
CONFIG_MTD_NAND=y : Enable NAND support
CONFIG_MTD_NAND_BLOCKCHECK=n : Interferes with NXFFS bad block checking
CONFIG_MTD_NAND_SWECC=y : Use S/W ECC calculation

Defaults for all other NAND settings should be okay

System Type -> External Memory Configuration
CONFIG_SAMA5_EBICS3=y : Enable External CS3 memory
CONFIG_SAMA5_EBICS3_NAND=y : Select NAND memory type
CONFIG_SAMA5_EBICS3_SIZE=8388608 : Use this size
CONFIG_SAMA5_EBICS3_SWECC=y : Use S/W ECC calculation

Defaults for ROM page table addresses should be okay

Application Configuration -> NSH Library
CONFIG_NSH_ARCHINIT=y : Use architecture-specific initialization

NOTES:

1. WARNING: This will wipe out everything that you may have on the NAND
FLASH! I have found that using the JTAG with no valid image on NAND
or Serial FLASH is a problem: In that case, the code always ends up
in the SAM-BA bootloader.

My understanding is that you can enable JTAG in this case by simply
entering any data on the DBG serial port. I have not tried this.
Instead, I just changed to boot from Serial Flash:

2. Unfortunately, there are no appropriate NAND file system in NuttX as
of this writing. The following sections discussion issues/problems
with using NXFFS and FAT.

PMECC
-----

Hardware ECC calculation using the SAMA5D3's PMECC can be enable as
follows:

Drivers -> Memory Technology Device (MTD) Support
CONFIG_MTD_NAND_SWECC=y : Don't use S/W ECC calculation
CONFIG_MTD_NAND_HWECC=y : Use H/W ECC instead

System Type -> External Memory Configuration
CONFIG_SAMA5_EBICS3_SWECC=n : Don't use S/W ECC calculation
CONFIG_SAMA5_HAVE_PMECC=n : Use H/W ECC instead

Other PMECC-related default settings should be okay.

STATUS: As of the writing, NAND transfers using PMECC appear to
work correctly. However, the PMECC based systems do not work as
as well with FAT or NXFFS. My belief that that the FAT/NXFFS layers
are inappropriate for NAND and, as a result, happen not to work with
the PMECC ECC calculation. See also the "STATUS SUMMARY" section below.

DMA Support
-----------

DMA support can be enabled as follows:

System Type -> SAMA5 Peripheral support
CONFIG_SAMA5_DMAC0=y : Use DMAC0 for memory-to-memory DMA

System Type -> External Memory Configuration
CONFIG_SAMA5_NAND_DMA=y : Use DMAC0 for NAND data transfers

STATUS: DMA appears to be functional, but probably has not been
exercised enough to claim that with any certainty. See also the "STATUS
SUMMARY" section below.

NXFFS
-----

The NuttX FLASH File System (NXFFS) works well with NOR-like FLASH
but does not work well with NAND (See comments below under STATUS)

File Systems:
CONFIG_FS_NXFFS=y : Enable the NXFFS file system

Defaults for all other NXFFS settings should be okay.

NOTE: NXFFS will require some significant buffering because of
the large size of the NAND flash blocks. You will also need
to enable SDRAM as described above.

Board Selection
CONFIG_SAMA5D3XPLAINED_NAND_BLOCKMOUNT=y : Enable FS support on NAND
CONFIG_SAMA5D3XPLAINED_NAND_NXFFS=y : Use the NXFFS file system

Other file systems are not recommended because only NXFFS can handle
bad blocks and only NXFFS performs wear-levelling.

FAT
---

Another option is FAT. FAT, however, is not appropriate for use with
NAND: FAT will not handle bad blocks, does not perform any wear
levelling, and may not conform to writing ordering requirements of NAND.
Also, there appear to be issues with FAT when PMECC is enabled (see
"STATUS SUMMARY" below).

File Systems:
CONFIG_FS_FAT=y : Enable the FAT FS
CONFIG_FAT_LCNAMES=y : With lower case name support
CONFIG_FAT_LFN=y : And (patented) FAT long file name support
CONFIG_FS_NXFFS=n : Don't need NXFFS

Defaults for all other NXFFS settings should be okay.

Board Selection
CONFIG_SAMA5D3XPLAINED_NAND_BLOCKMOUNT=y : Enable FS support on NAND
CONFIG_SAMA5D3XPLAINED_NAND_FTL=y : Use an flash translation layer

NOTE: FTL will require some significant buffering because of
the large size of the NAND flash blocks. You will also need
to enable SDRAM as described above.

SMART FS
--------

Another option is Smart FS. Smart FS is another small file system
designed to work with FLASH. Properties: It does support some wear-
leveling like NXFFS, but like FAT, cannot handle bad blocks and like
NXFFS, it will try to re-write erased bits.

Using NAND with NXFFS
---------------------

With the options CONFIG_SAMA5D3XPLAINED_NAND_BLOCKMOUNT=y and
CONFIG_SAMA5D3XPLAINED_NAND_NXFFS=y, the NAND FLASH will be mounted in the NSH
start-up logic before the NSH prompt appears. There is no feedback as
to whether or not the mount was successful. You can, however, see the
mounted file systems using the nsh 'mount' command:

nsh> mount
/mnt/nand type nxffs

Then NAND can be used like any other file system:

nsh> echo "This is a test" >/mnt/nand/atest.txt
nsh> ls -l /mnt/nand
/mnt/nand:
---x--x--x 16 atest.txt
nsh> cat /mnt/nand/atest.txt
This is a test

The NAND volume can be un-mounted with this comment:

nsh> umount /mnt/nand
nsh> mount

And re-mounted with this command:

nsh> mount -t nxffs /mnt/mystuff
nsh> mount
/mnt/mystuff type nxffs

NOTES:
1. NXFFS can be very slow. The first time that you start the system,
be prepared for a wait; NXFFS will need to format the NAND volume.
I have lots of debug on so I don't yet know what the optimized wait
will be. But with debug ON, software ECC, and no DMA the wait is
in many tens of minutes (and substantially longer if many debug
options are enabled.

[I don't yet have data for the more optimal cases. It will be
significantly less, but still not fast.]

2. On subsequent boots, after the NXFFS file system has been created
the delay will be less. When the new file system is empty, it will
be very fast. But the NAND-related boot time can become substantial
when there has been a lot of usage of the NAND. This is because
NXFFS needs to scan the NAND device and build the in-memory dataset
needed to access NAND and there is more that must be scanned after
the device has been used. You may want to create a separate thread at
boot time to bring up NXFFS so that you don't delay the boot-to-prompt
time excessively in these longer delay cases.

3. There is another NXFFS related performance issue: When the FLASH
is fully used, NXFFS will restructure the entire FLASH, the delay
to restructure the entire FLASH will probably be even larger. This
solution in this case is to implement an NXFSS clean-up daemon that
does the job a little-at-a-time so that there is no massive clean-up
when the FLASH becomes full.

4. Bad NXFFS behavior with NAND: If you restart NuttX, the files that
you wrote to NAND will be gone. Why? Because the multiple writes
have corrupted the NAND ECC bits. See STATUS below. NXFFS would
require a major overhaul to be usable with NAND.

Using NAND with FAT
-------------------

If configured for FAT, the system will create block driver at
/dev/mtdblock0:

NuttShell (NSH)
nsh> ls /dev
/dev:
console
mtdblock0
null
ttyS0

You will not that the system comes up immediately because there is not
need to scan the volume in this case..

The NSH 'mkfatfs' command can be used to format a FAT file system on
NAND.

nsh> mkfatfs /dev/mtdblock0

This step, on the other hand, requires quite a bit of time.

And the FAT file system can be mounted like:

nsh> mount -t vfat /dev/mtdblock0 /mnt/nand
nsh> ls /mnt/nand
/mnt/nand:

nsh> echo "This is a test" > /mnt/nand/atest.txt

NOTE: This will take a long time because it will require reading,
modifying, and re-writing the 128KB erase page!

nsh> ls -l /mnt/nand
/mnt/nand:
-rw-rw-rw- 16 atest.txt

nsh> cat /mnt/fat/atest.txt
This is a test

NOTES:

1. Unlike NXFFS, FAT can work with NAND (at least with PMECC disabled).
But there are some significant issues.

2. First, each NAND write access will cause a 256KB data transfer: It
will read the entire 128KB erase block, modify it and write it back
to memory. There is some caching logic so that this cached erase
block can be re-used if possible and writes will be deferred as long
as possible.

3. If you hit a bad block, then FAT is finished. There is no mechanism
in place in FAT not to mark and skip over bad blocks.

What is Needed
--------------

What is needed to work with FAT properly would be another MTD layer
between the FTL layer and the NAND FLASH layer. That layer would
perform bad block detection and sparing so that FAT works transparently
on top of the NAND.

Another, less general, option would be support bad blocks within FAT.

STATUS SUMMARY
--------------

1. PMECC appears to be working in that I can write a NAND block with its
ECC and read the block back and verify that that is are no bit
failures. However, when attempting to work with FAT, it does not
work correctly: The MBR is written and read back correctly, but gets
corrupted later for unknown reasons.

2. DMA works (at least with software ECC), but I have seen occasional
failures. I recommend enabling DMA with caution.

In NuttX, DMA will also cost two context switches (and, hence, four
register state transfers). With smaller NAND page sizes (say 2KiB and
below), I would expect little or no performance improvement with DMA
for this reason.

3. NXFFS does not work with NAND. NAND differs from other other FLASH
types several ways. For one thing, NAND requires error correction
(ECC) bytes that must be set in order to work around bit failures.
This affects NXFFS in two ways:

a. First, write failures are not fatal. Rather, they should be tried by
bad blocks and simply ignored. This is because unrecoverable bit
failures will cause read failures when reading from NAND. Setting
the CONFIG_EXPERIMENTAL+CONFIG_NXFFS_NANDs option will enable this
behavior.

b. Secondly, NXFFS will write a block many times. It tries to keep
bits in the erased state and assumes that it can overwrite those bits
to change them from the erased to the non-erased state. This works
will with NOR-like FLASH. NAND behaves this way too. But the
problem with NAND is that the ECC bits cannot be re-written in this
way. So once a block has been written, it cannot be modified. This
behavior has NOT been fixed in NXFFS. Currently, NXFFS will attempt
to re-write the ECC bits causing the ECC to become corrupted because
the ECC bits cannot be overwritten without erasing the entire block.

This may prohibit NXFFS from ever being used with NAND.

4. As mentioned above, FAT does work but (1) has some performance issues on
writes and (2) cannot handle bad blocks.

5. There was a major reorganization of the SAMA5 code after NuttX-7.11 to
add support for the SAMA5D2. Only the SAMA5D4-EK nsh configuration was
re-verified on 2015-09-29. But as of this writing, none of the SAMA5D3-
Xplained configurations a been re-verified. Some regression testing is
needed.

I2C Tool
========

I2C Tool. NuttX supports an I2C tool at apps/system/i2c that can be used
to peek and poke I2C devices. That tool can be enabled by setting the
following:

System Type -> SAMA5 Peripheral Support
CONFIG_SAMA5_TWI0=y : Enable TWI0
CONFIG_SAMA5_TWI1=y : Enable TWI1
CONFIG_SAMA5_TWI2=y : Enable TWI2

System Type -> TWI device driver options
SAMA5_TWI0_FREQUENCY=100000 : Select a TWI0 frequency
SAMA5_TWI1_FREQUENCY=100000 : Select a TWI1 frequency
SAMA5_TWI2_FREQUENCY=100000 : Select a TWI2 frequency

Device Drivers -> I2C Driver Support
CONFIG_I2C=y : Enable I2C support

Application Configuration -> NSH Library
CONFIG_SYSTEM_I2CTOOL=y : Enable the I2C tool
CONFIG_I2CTOOL_MINBUS=0 : TWI0 has the minimum bus number 0
CONFIG_I2CTOOL_MAXBUS=2 : TWI2 has the maximum bus number 2
CONFIG_I2CTOOL_DEFFREQ=100000 : Pick a consistent frequency

The I2C tool has extensive help that can be accessed as follows:

nsh> i2c help
Usage: i2c <cmd> [arguments]
Where <cmd> is one of:

Show help : ?
List busses : bus
List devices : dev [OPTIONS] <first> <last>
Read register : get [OPTIONS] [<repititions>]
Show help : help
Write register: set [OPTIONS] <value> [<repititions>]
Verify access : verf [OPTIONS] [<value>] [<repititions>]

Where common "sticky" OPTIONS include:
[-a addr] is the I2C device address (hex). Default: 03 Current: 03
[-b bus] is the I2C bus number (decimal). Default: 0 Current: 0
[-r regaddr] is the I2C device register address (hex). Default: 00 Current: 00
[-w width] is the data width (8 or 16 decimal). Default: 8 Current: 8
[-s|n], send/don't send start between command and data. Default: -n Current: -n
[-i|j], Auto increment|don't increment regaddr on repititions. Default: NO Current: NO
[-f freq] I2C frequency. Default: 100000 Current: 100000

NOTES:
o Arguments are "sticky". For example, once the I2C address is
specified, that address will be re-used until it is changed.

WARNING:
o The I2C dev command may have bad side effects on your I2C devices.
Use only at your own risk.

As an example, the I2C dev comman can be used to list all devices
responding on TWI0 (the default) like this:

nsh> i2c dev 0x03 0x77
0 1 2 3 4 5 6 7 8 9 a b c d e f
00: -- -- -- -- -- -- -- -- -- -- -- -- --
10: -- -- -- -- -- -- -- -- -- -- 1a -- -- -- -- --
20: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
30: -- -- -- -- -- -- -- -- -- 39 -- -- -- 3d -- --
40: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
50: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
60: 60 -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
70: -- -- -- -- -- -- -- --
nsh>

Address 0x1a is the WM8904. Address 0x39 is the SIL9022A. I am not sure
what is at address 0x3d and 0x60

CAN Usage
=========
I planned to verify CAN using the IXXAT USB-to-CAN Compact. This section
provides miscellaneous CAN-related notes, mostly to myself but perhaps of
interest to others.

[Unfortunately, as of this writing, I still do not have a proper CAN test
bed to verify the CAN driver.]

CAN Configuration
-----------------

The following steps illustrate how to enable CAN0 and/or CAN1 in the NuttX
configuration:

System Type -> SAMA5 Peripheral Support
CONFIG_SAMA5_CAN0=y : Select CAN0 and/or CAN1
CONFIG_SAMA5_CAN1=y

Device Drivers -> CAN Driver Support
CONFIG_CAN=y : (Automatically selected)
CONFIG_CAN_EXTID=y : For extended, 29-bit CAN IDs

System Type -> CAN Drive Support
CONFIG_SAMA5_CAN0_BAUD=250000 : Select some BAUD for CAN0 (if enabled)
CONFIG_SAMA5_CAN0_NRECVMB=1 : Select number of receive mailboxes (see below)
CONFIG_SAMA5_CAN1_BAUD=250000 : Select some BAUD for CAN1 (if enabled)
CONFIG_SAMA5_CAN1_NRECVMB=1 : Select number of receive mailboxes (see below)

Receive Mailboxes and Address Filtering
---------------------------------------

The SAMA5 CAN0 peripheral supports 8 mailboxes that can be used for sending
and receiving messages. Note that the number of dedicated receive mailboxes
(CONFIG_SAMA5_CANn_NRECVMB) was set to one in the above configuration. This
could be set to any value from 1 to 3 (the upper limit of 3 is purely
arbrary and can be increased with some minor code enhancement). The
remainder can be configured dynamically to send CAN messages.

Why would you want to use more than one receive mailbox? There are two
reasons. Multiple receive mailboxes might needed to either (1) receive
bursts of messages, or (2) to support multiple groups of messages filtered
on message ID.

You must also specify the address filtering for each dedicated receive mailbox:

System Type -> CAN Drive Support
CONFIG_SAMA5_CAN0_ADDR0 and CONFIG_SAMA5_CAN0_MASK0 : If CONFIG_SAMA5_CAN0_NRECVMB >= 1
CONFIG_SAMA5_CAN0_ADDR1 and CONFIG_SAMA5_CAN0_MASK1 : If CONFIG_SAMA5_CAN0_NRECVMB >= 2
CONFIG_SAMA5_CAN0_ADDR2 and CONFIG_SAMA5_CAN0_MASK2 : If CONFIG_SAMA5_CAN0_NRECVMB >= 3
CONFIG_SAMA5_CAN1_ADDR0 and CONFIG_SAMA5_CAN1_MASK0 : If CONFIG_SAMA5_CAN1_NRECVMB >= 1
CONFIG_SAMA5_CAN1_ADDR1 and CONFIG_SAMA5_CAN1_MASK1 : If CONFIG_SAMA5_CAN1_NRECVMB >= 2
CONFIG_SAMA5_CAN1_ADDR2 and CONFIG_SAMA5_CAN1_MASK2 : If CONFIG_SAMA5_CAN1_NRECVMB >= 3

Only messages that have IDs that match the CONFIG_SAMA5_CANn_ADDRn when both
the received and the configured address are masked by CONFIG_SAMA5_CANn_MASKn
will be accepted. For example, if the mask is all ones, then only messasges
with exact address matches will be accepted; if the mask is all zeroes than
any address will be accepted.

CAN connectors
--------------

CAN1 and CAN2 are available via RJ-11 connectors on the SAMA5D3-Xplained. Each
is wired as follows. Also shown below is the matching pins if you want connect
the CAN to a device that uses an DB-9 connector (Such as the IXXAT USB-to-CAN
Compact). Both connector types (as well as RJ-45) are common.

+----------+ RJ-11 DB-9
| O | ----------- --------------
+------------+ | | Pin 1 3v3 Pin 1 N/C
| +--+ | | o5 | Pin 2 5v Pin 2 CANL
| | | | | o9 | Pin 3 N/C Pin 3 GND
| +-+ +-+ | | o4 | Pin 4 CANL Pin 4 N/C
| | | | | o8 | Pin 5 CANH Pin 5 N/C
| |654321| | | o3 | Pin 6 N/C Pin 6 N/C
| |oooooo| | | o7 | Pin 7 CANH
| +------+ | | o2 | Pin 8 N/C
+------------+ | o6 | Pin 9 CANV+ (N/C on IXXAT) RJ-11 Female | x1 |
| |
| O |
+----------+
DB-9 Male

SAMA5 ADC Support
=================

Basic driver configuration
--------------------------
ADC support can be added to the NSH configuration. However, there are no
ADC input pins available to the user for ADC testing (the touchscreen ADC
inputs are intended for other functionality). Because of this, there is
not much motivation to enable ADC support on the SAMA5D3-Xplained. This
paragraph is included here, however, for people using a custom SAMA5D3x
board that requires ADC support.

System Type -> SAMA5 Peripheral Support
CONFIG_SAMA5_ADC=y : Enable ADC driver support
CONFIG_SAMA5_TC0=y : Enable the Timer/counter library need for periodic sampling

Drivers
CONFIG_ANALOG=y : Should be automatically selected
CONFIG_ADC=y : Should be automatically selected

System Type -> ADC Configuration
CONFIG_SAMA5_ADC_CHAN0=y : These settings enable the sequencer to collect
CONFIG_SAMA5_ADC_CHAN1=y : Samples from ADC channels 0-3 on each trigger
CONFIG_SAMA5_ADC_CHAN2=y
CONFIG_SAMA5_ADC_CHAN3=y
CONFIG_SAMA5_ADC_SEQUENCER=y

CONFIG_SAMA5_ADC_TIOA0TRIG=y : Trigger on the TC0, channel 0 output A
CONFIG_SAMA5_ADC_TIOAFREQ=2 : At a frequency of 2Hz
CONFIG_SAMA5_ADC_TIOA_RISING=y : Trigger on the rising edge

Default ADC settings (like gain and offset) may also be set if desired.

System Type -> Timer/counter Configuration
CONFIG_SAMA5_TC0_TIOA0=y : Should be automatically selected

Work queue supported is also needed:

Library routines
CONFIG_SCHED_WORKQUEUE=y

ADC Test Example
----------------
For testing purposes, there is an ADC program at apps/examples/adc that
will collect a specified number of samples. This test program can be
enabled as follows:

Application Configuration -> Examples -> ADC example
CONFIG_EXAMPLES_ADC=y : Enables the example code
CONFIG_EXAMPLES_ADC_DEVPATH="/dev/adc0"

Other default settings for the ADC example should be okay.

ADC DMA Support
---------------
At 2Hz, DMA is not necessary nor desire-able. The ADC driver has support
for DMA transfers of converted data (although that support has not been
tested as of this writing). DMA support can be added by include the
following in the configuration.

System Type -> SAMA5 Peripheral Support
CONFIG_SAMA5_DMAC1=y : Enable DMAC1 support

System Type -> ADC Configuration
CONFIG_SAMA5_ADC_DMA=y : Enable ADC DMA transfers
CONFIG_SAMA5_ADC_DMASAMPLES=2 : Collect two sets of samples per DMA

Drivers -> Analog device (ADC/DAC) support
CONFIG_ADC_FIFOSIZE=16 : Driver may need a large ring buffer

Application Configuration -> Examples -> ADC example
CONFIG_EXAMPLES_ADC_GROUPSIZE=16 : Larger buffers in the test

SAMA5 PWM Support
=================

Basic driver configuration
--------------------------
PWM support can be added to the NSH configuration. However, there are no
PWM output pins available to the user for PWM testing. Because of this,
there is not much motivation to enable PWM support on the SAMA5D3-Xplained. This
paragraph is included here, however, for people using a custom SAMA5D3x
board that requires PWM support.

Basic driver configuration:

System Type -> SAMA5 Peripheral Support
CONFIG_SAMA5_PWM=y : Enable PWM driver support

Drivers
CONFIG_PWM=y : Should be automatically selected

PWM Channel/Output Selection
----------------------------
In order to use the PWM, you must enable one or more PWM Channels:

System Type -> PWM Configuration
CONFIG_SAMA5_PWM_CHAN0=y : Enable one or more of channels 0-3
CONFIG_SAMA5_PWM_CHAN1=y
CONFIG_SAMA5_PWM_CHAN2=y
CONFIG_SAMA5_PWM_CHAN3=y

For each channel that is enabled, you must also specify the output pins
to be enabled and the clocking supplied to the PWM channel.

CONFIG_SAMA5_PWM_CHANx_FAULTINPUT=n : (not used currently)
CONFIG_SAMA5_PWM_CHANx_OUTPUTH=y : Enable One of both of the H and L output pins
CONFIG_SAMA5_PWM_CHANx_OUTPUTL=y

Where x=0..3.

Care must be taken because all PWM output pins conflict with some other
usage of the pin by other devices. Furthermore, many of these pins have
not been brought out to an external connector:

-----+---+---+----+------+----------------
PWM PIN PER PIO I/O CONFLICTS
-----+---+---+----+------+----------------
PWM0 FI B PC28 J2.30 SPI1, ISI
H B PB0 --- GMAC
B PA20 J1.14 LCDC, ISI
L B PB1 --- GMAC
B PA21 J1.16 LCDC, ISI
-----+---+---+----+------+----------------
PWM1 FI B PC31 J2.36 HDMI
H B PB4 --- GMAC
B PA22 J1.18 LCDC, ISI
L B PB5 --- GMAC
B PE31 J3.20 ISI, HDMI
B PA23 J1.20 LCDC, ISI
-----+---+---+----+------+----------------
PWM2 FI B PC29 J2.29 UART0, ISI, HDMI
H C PD5 --- HSMCI0
B PB8 --- GMAC
L C PD6 --- HSMCI0
B PB9 --- GMAC
-----+---+---+----+------+----------------
PWM3 FI C PD16 --- SPI0, Audio
H C PD7 --- HSMCI0
B PB12 J3.7 GMAC
L C PD8 --- HSMCI0
B PB13 --- GMAC
-----+---+---+----+--------------------

See configs/sama5d3-xplained/include/board.h for all of the default PWM
pin selections. I used PWM channel 0, pins PA20 and PA21 for testing.

Clocking is addressed in the next paragraph.

PWM Clock Configuration
-----------------------
PWM Channels can be clocked from either a coarsely divided divided down
MCK or from a custom frequency from PWM CLKA and/or CLKB. If you want
to use CLKA or CLKB, you must enable and configure them.

System Type -> PWM Configuration
CONFIG_SAMA5_PWM_CLKA=y
CONFIG_SAMA5_PWM_CLKA_FREQUENCY=3300
CONFIG_SAMA5_PWM_CLKB=y
CONFIG_SAMA5_PWM_CLKB_FREQUENCY=3300

Then for each of the enabled, channels you must select the input clock
for that channel:

System Type -> PWM Configuration
CONFIG_SAMA5_PWM_CHANx_CLKA=y : Pick one of MCK, CLKA, or CLKB (only)
CONFIG_SAMA5_PWM_CHANx_CLKB=y
CONFIG_SAMA5_PWM_CHANx_MCK=y
CONFIG_SAMA5_PWM_CHANx_MCKDIV=128 : If MCK is selected, then the MCK divider must
: also be provided (1,2,4,8,16,32,64,128,256,512, or 1024).

PWM Test Example
----------------
For testing purposes, there is an PWM program at apps/examples/pwm that
will collect a specified number of samples. This test program can be
enabled as follows:

Application Configuration -> Examples -> PWM example
CONFIG_EXAMPLES_PWM=y : Enables the example code

Other default settings for the PWM example should be okay.

CONFIG_EXAMPLES_PWM_DEVPATH="/dev/pwm0"
CONFIG_EXAMPLES_PWM_FREQUENCY=100

Usage of the example is straightforward:

nsh> pwm -h
Usage: pwm [OPTIONS]

Arguments are "sticky". For example, once the PWM frequency is
specified, that frequency will be re-used until it is changed.

"sticky" OPTIONS include:
[-p devpath] selects the PWM device. Default: /dev/pwm0 Current: /dev/pwm0
[-f frequency] selects the pulse frequency. Default: 100 Hz Current: 100 Hz
[-d duty] selects the pulse duty as a percentage. Default: 50 % Current: 50 %
[-t duration] is the duration of the pulse train in seconds. Default: 5 Current: 5
[-h] shows this message and exits

RTC
===

The Real Time Clock/Calendar RTC) may be enabled with these settings:

System Type:
CONFIG_SAMA5_RTC=y : Enable the RTC driver

Drivers (these values will be selected automatically):
CONFIG_RTC=y : Use the RTC for system time
CONFIG_RTC_DATETIME=y : RTC supports data/time

You can set the RTC using the NSH date command:

NuttShell (NSH) NuttX-7.3
nsh> help date
date usage: date [-s "MMM DD HH:MM:SS YYYY"]
nsh> date
Jan 01 00:34:45 2012
nsh> date -s "JUN 29 7:30:00 2014"
nsh> date
Jun 29 07:30:01 2014

After a power cycle and reboot:

NuttShell (NSH) NuttX-7.3
nsh> date
Jun 29 07:30:55 2014
nsh>

The RTC also supports an alarm that may be enable with the following
settings. However, there is nothing in the system that currently makes
use of this alarm.

Drivers:
CONFIG_RTC_ALARM=y : Enable the RTC alarm

Library Routines
CONFIG_SCHED_WORKQUEUE=y : Alarm needs work queue support

Watchdog Timer
==============

NSH can be configured to exercise the watchdog timer test
(apps/examples/watchdog). This can be selected with the following
settings in the NuttX configuration file:

System Type:
CONFIG_SAMA5_WDT=y : Enable the WDT peripheral
: Defaults in "RTC Configuration" should be OK

Drivers (this will automatically be selected):
CONFIG_WATCHDOG=y : Enables watchdog timer driver support

Application Configuration -> Examples
CONFIG_EXAMPLES_WATCHDOG=y : Enable apps/examples/watchdog

The WDT timer is driven off the slow, 32768Hz clock divided by 128. As a
result, the watchdog a maximum timeout value of 16 seconds. The SAMA5 WDT
may also only be programmed one time; the processor must be reset before
the WDT can be reprogrammed.

The SAMA5 always boots with the watchdog timer enabled at its maximum
timeout (16 seconds). In the normal case where no watchdog timer driver
has been configured, the watchdog timer is disabled as part of the start
up logic. But, since we are permitted only one opportunity to program
the WDT, we cannot disable the watchdog time if CONFIG_SAMA5_WDT=y. So,
be forewarned: You have only 16 seconds to run your watchdog timer test!

TRNG and /dev/random
====================

NSH can be configured to enable the SAMA5 TRNG peripheral so that it
provides /dev/random. The following configuration will enable the TRNG,
and support for /dev/random:

System Type:
CONFIG_SAMA5_TRNG=y : Enable the TRNG peripheral

Drivers:
CONFIG_DEV_RANDOM=y : Enable /dev/random

A simple test of /dev/random is available at apps/examples/random and
can be enabled as a NSH application via the following additional
configuration settings:

Applications -> Examples
CONFIG_EXAMPLES_RANDOM=y : Enable apps/examples/random
CONFIG_EXAMPLES_MAXSAMPLES=64 : Default settings are probably OK
CONFIG_EXAMPLES_NSAMPLES=8

Tickless OS
===========

Background
----------
By default, a NuttX configuration uses a periodic timer interrupt that
drives all system timing. The timer is provided by architecture-specifi
code that calls into NuttX at a rate controlled by CONFIG_USEC_PER_TICK.
The default value of CONFIG_USEC_PER_TICK is 10000 microseconds which
corresponds to a timer interrupt rate of 100 Hz.

An option is to configure NuttX to operation in a "tickless" mode. Some
limitations of default system timer are, in increasing order of
importance:

- Overhead: Although the CPU usage of the system timer interrupt at 100Hz
is really very low, it is still mostly wasted processing time. One most
timer interrupts, there is really nothing that needs be done other than
incrementing the counter.
- Resolution: Resolution of all system timing is also determined by
CONFIG_USEC_PER_TICK. So nothing that be time with resolution finer than
10 milliseconds be default. To increase this resolution,
CONFIG_USEC_PER_TICK an be reduced. However, then the system timer
interrupts use more of the CPU bandwidth processing useless interrupts.
- Power Usage: But the biggest issue is power usage. When the system is
IDLE, it enters a light, low-power mode (for ARMs, this mode is entered
with the wfi or wfe instructions for example). But each interrupt
awakens the system from this low power mode. Therefore, higher rates
of interrupts cause greater power consumption.

The so-called Tickless OS provides one solution to issue. The basic
concept here is that the periodic, timer interrupt is eliminated and
replaced with a one-shot, interval timer. It becomes event driven
instead of polled: The default system timer is a polled design. On
each interrupt, the NuttX logic checks if it needs to do anything
and, if so, it does it.

Using an interval timer, one can anticipate when the next interesting
OS event will occur, program the interval time and wait for it to fire.
When the interval time fires, then the scheduled activity is performed.

Configuration
-------------
The following configuration options will enable support for the Tickless
OS for the SAMA5D platforms using TC0 channels 0-3 (other timers or
timer channels could be used making the obvious substitutions):

RTOS Features -> Clocks and Timers
CONFIG_SCHED_TICKLESS=y : Configures the RTOS in tickless mode
CONFIG_SCHED_TICKLESS_ALARM=n : (option not implemented)

System Type -> SAMA5 Peripheral Support
CONFIG_SAMA5_TC0=y : Enable TC0 (TC channels 0-3

System Type -> Timer/counter Configuration
CONFIG_SAMA5_ONESHOT=y : Enables one-shot timer wrapper
CONFIG_SAMA5_FREERUN=y : Enabled free-running timer wrapper
CONFIG_SAMA5_TICKLESS_ONESHOT=0 : Selects TC0 channel 0 for the one-shot
CONFIG_SAMA5_TICKLESS_FREERUN=1 : Selects TC0 channel 1 for the free-
: running timer

The resolution of the clock is provided by the CONFIG_USEC_PER_TICK
setting in the configuration file.

NOTE: In most cases, the slow clock will be used as the timer/counter
input. You should enable the 32.768KHz crystal for the slow clock by
calling sam_sckc_enable(). Otherwise, you will be doing all system
timing using the RC clock! UPDATE: This will now be selected by default
when you configure for TICKLESS support.

The slow clock has a resolution of about 30.518 microseconds. Ideally,
the value of CONFIG_USEC_PER_TICK should be the exact clock resolution.
Otherwise there will be cumulative timing inaccuracies. But a choice
choice of:

CONFIG_USEC_PER_TICK=31

will have an error of 0.6% and will have inaccuracies that will
effect the time due to long term error build-up.

UPDATE: As of this writing (2015-12-03), the Tickless support is
functional. However, there are inaccuracies in delays. For example,

nsh> sleep 10

results in a delay of maybe 5.4 seconds. But the timing accuracy is
correct if all competing uses of the interval timer are disabled (mostly
from the high priority work queue). Therefore, I conclude that this
inaccuracy is due to the inaccuracies in the representation of the clock
rate. 30.518 usec cannot be represented accurately. Each timing
calculation results in a small error. When the interval timer is very
busy, long delays will be divided into many small pieces and each small
piece has a large error in the calculation. The cumulative error is the
cause of the problem.

SAMA5 Timer Usage
-----------------
This current implementation uses two timers: A one-shot timer to
provide the timed events and a free running timer to provide the current
time. Since timers are a limited resource, that could be an issue on
some systems.

We could do the job with a single timer if we were to keep the single
timer in a free-running at all times. The SAMA5 timer/counters have
32-bit counters with the capability to generate a compare interrupt when
the timer matches a compare value but also to continue counting without
stopping (giving another, different interrupt when the timer rolls over
from 0xffffffff to zero). So we could potentially just set the compare
at the number of ticks you want PLUS the current value of timer. Then
you could have both with a single timer: An interval timer and a free-
running counter with the same timer! In this case, you would want to
to set CONFIG_SCHED_TICKLESS_ALARM in the NuttX configuration.

Patches are welcome!

I2S Audio Support
=================

The SAMA5D3-Xplained has two devices on-board that can be used for verification
of I2S functionality: HDMI and a WM8904 audio CODEC. As of this writing,
the I2S driver is present, but there are not drivers for either the HDMI
or the WM8904.

WM8904 Audio CODEC Interface
----------------------------

------------- ---------------- -----------------
WM8904 SAMA5D3 NuttX Pin Name
------------- ---------------- -----------------
3 SDA PA30 TWD0 PIO_TWI0_D
2 SCLK PA31 TWCK0 PIO_TWI0_CK
28 MCLK PD30 PCK0 PIO_PMC_PCK0
29 BCLK/GPIO4 PC16 TK PIO_SSC0_TK
"" " " PC19 RK PIO_SSC0_RK
30 LRCLK PC17 TF PIO_SSC0_TF
"" " " PC20 RF PIO_SSC0_RF
31 ADCDAT PC21 RD PIO_SSC0_RD
32 DACDAT PC18 TD PIO_SSC0_TD
1 IRQ/GPIO1 PD16 INT_AUDIO N/A
------------- ---------------- -----------------

I2S Loopback Test
-----------------

The I2S driver was verified using a special I2C character driver (at
nuttx/drivers/audio/i2schar.c) and a test driver at apps/examples/i2schar.
The I2S driver was verified in loopback mode with no audio device.

[NOTE: The above statement is anticipatory: As of this writing I2S driver
verification is underway and still not complete].

This section describes the modifications to the NSH configuration that were
used to perform the I2S testing:

System Type -> SAMA5 Peripheral Support
CONFIG_SAMA5_SSCO=y : Enable SSC0 driver support
CONFIG_SAMA5_DMAC0=y : DMAC0 required by SSC0

Alternatively, SSC1 could have be used:

System Type -> SAMA5 Peripheral Support
CONFIG_SAMA5_SSC1=y : Enable SSC0 driver support
CONFIG_SAMA5_DMAC1=y : DMAC0 required by SSC0

System Type -> SSC Configuration
CONFIG_SAMA5_SSC_MAXINFLIGHT=16 : Up to 16 pending DMA transfers
CONFIG_SAMA5_SSC0_MASTER=y : Master mode
CONFIG_SAMA5_SSC0_DATALEN=16 : 16-bit data
CONFIG_SAMA5_SSC0_RX=y : Support a receiver
CONFIG_SAMA5_SSC0_RX_RKINPUT=y : Receiver gets clock from RK input
CONFIG_SAMA5_SSC0_TX=y : Support a transmitter
CONFIG_SAMA5_SSC0_TX_MCKDIV=y : Transmitter gets clock from MCK/2
CONFIG_SAMA5_SSC0_MCKDIV_SAMPLERATE=48000 : Sampling at 48K samples/sec
CONFIG_SAMA5_SSC0_TX_TKOUTPUT_XFR=y : Outputs clock on TK when transferring data
CONFIG_SAMA5_SSC0_LOOPBACK=y : Loopmode mode connects RD/TD and RK/TK

Audio
CONFIG_AUDIO=y : Audio support needed
: Defaults should be okay

Drivers -> Audio
CONFIG_I2S=y : General I2S support
CONFIG_DRIVERS_AUDIO=y : Audio device support
CONFIG_AUDIO_I2SCHAR=y : Build I2S character driver

The following describes how I have the test application at
apps/examples/i2schar configured:

CONFIG_EXAMPLES_I2SCHAR=y
CONFIG_EXAMPLES_I2SCHAR_DEVPATH="/dev/i2schar0"
CONFIG_EXAMPLES_I2SCHAR_TX=y
CONFIG_EXAMPLES_I2SCHAR_TXBUFFERS=4
CONFIG_EXAMPLES_I2SCHAR_TXSTACKSIZE=1536
CONFIG_EXAMPLES_I2SCHAR_RX=y
CONFIG_EXAMPLES_I2SCHAR_RXBUFFERS=4
CONFIG_EXAMPLES_I2SCHAR_RXSTACKSIZE=1536
CONFIG_EXAMPLES_I2SCHAR_BUFSIZE=256
CONFIG_EXAMPLES_I2SCHAR_DEVINIT=y

Board Selection
CONFIG_SAMA5D3XPLAINED_I2SCHAR_MINOR=0
CONFIG_SAMA5D3XPLAINED_SSC_PORT=0 : 0 or SSC0, 1 for SSC1

Library Routines
CONFIG_SCHED_WORKQUEUE=y : Driver needs work queue support

Shields
=======

Support is built in for the following shields:

Itead Joystick Shield
---------------------
See http://imall.iteadstudio.com/im120417014.html for more information
about this joystick.

Itead Joystick Connection:

--------- ----------------- ---------------------------------
ARDUINO ITEAD SAMA5D3 XPLAINED
PIN NAME SIGNAL CONNECTOR SIGNAL
--------- ----------------- ---------- ----------------------
D3 Button E Output J18 pin 4 PC8
D4 Button D Output J18 pin 5 PC28
D5 Button C Output J18 pin 6 PC7
D6 Button B Output J18 pin 7 PC6
D7 Button A Output J18 pin 8 PC5
D8 Button F Output J15 pin 1 PC4
D9 Button G Output J15 pin 2 PC3
A0 Joystick Y Output J17 pin 1 PC18 AD0 (function 4)
A1 Joystick X Output J17 pin 2 PD21 AD1 (function 1)
--------- ----------------- ---------- ----------------------

All buttons are pulled on the shield. A sensed low value indicates
when the button is pressed.

Possible conflicts:

---- ----- --------------------------------------------------
ARDU SAMA5 SAMA5D3 XPLAINED
PIN GPIO SIGNAL FUNCTION
---- ----- ----------------- --------------------------------
D3 PC8 EMDC 10/100Mbit Ethernet MAC
D4 PC28 SPI1_NPCS3/ISI_D9 SPI1/ISI
D5 PC7 EREFCK 10/100Mbit Ethernet MAC
D6 PC6 ECRSDV 10/100Mbit Ethernet MAC
D7 PC5 ECRSDV 10/100Mbit Ethernet MAC
D8 PC4 ETXEN 10/100Mbit Ethernet MAC
D9 PC3 ERX1 10/100Mbit Ethernet MAC
A0 PC18 RK0 SSC/Audio
A1 PC21 RD0 SSC/Audio
---- ----- ----------------- --------------------------------

Itead Joystick Signal interpretation:

--------- ----------------------- ---------------------------
BUTTON TYPE NUTTX ALIAS
--------- ----------------------- ---------------------------
Button A Large button A JUMP/BUTTON 3
Button B Large button B FIRE/BUTTON 2
Button C Joystick select button SELECT/BUTTON 1
Button D Tiny Button D BUTTON 6
Button E Tiny Button E BUTTON 7
Button F Large Button F BUTTON 4
Button G Large Button G BUTTON 5
--------- ----------------------- ---------------------------

Itead Joystick configuration settings:

System Type -> SAMA5 Peripheral Support
CONFIG_SAMA5_ADC=y : Enable ADC driver support
CONFIG_SAMA5_TC0=y : Enable the Timer/counter library need for periodic sampling
CONFIG_SAMA5_EMACA=n : 10/100Mbit Ethernet MAC conflicts
CONFIG_SAMA5_SSC0=n : SSC0 Audio conflicts
CONFIG_SAMA5_SPI1=? : SPI1 might conflict if PCS3 is used
CONFIG_SAMA5_ISI=? : ISIS conflics if bit 9 is used

System Type -> PIO Interrupts
CONFIG_SAMA5_PIO_IRQ=y : PIO interrupt support is required
CONFIG_SAMA5_PIOC_IRQ=y : PIOC interrupt support is required

Drivers
CONFIG_ANALOG=y : Should be automatically selected
CONFIG_ADC=y : Should be automatically selected
CONFIG_INPUT=y : Select input device support
CONFIG_AJOYSTICK=y : Select analog joystick support

System Type -> ADC Configuration
CONFIG_SAMA5_ADC_CHAN0=y : These settings enable the sequencer to collect
CONFIG_SAMA5_ADC_CHAN1=y : Samples from ADC channels 0-1 on each trigger
CONFIG_SAMA5_ADC_SEQUENCER=y
CONFIG_SAMA5_ADC_TIOA0TRIG=y : Trigger on the TC0, channel 0 output A
CONFIG_SAMA5_ADC_TIOAFREQ=10 : At a frequency of 10Hz
CONFIG_SAMA5_ADC_TIOA_RISING=y : Trigger on the rising edge

Default ADC settings (like gain and offset) may also be set if desired.

System Type -> Timer/counter Configuration
CONFIG_SAMA5_TC0_TIOA0=y : Should be automatically selected

Library routines
CONFIG_SCHED_WORKQUEUE=y : Work queue support is needed

There is nothing in the configuration that currently uses the joystick.
For testing, you can add the following configuration options to enable the
analog joystick example at apps/examples/ajoystick:

CONFIG_NSH_ARCHINIT=y
CONFIG_EXAMPLES_AJOYSTICK=y
CONFIG_EXAMPLES_AJOYSTICK_DEVNAME="/dev/ajoy0"
CONFIG_EXAMPLES_AJOYSTICK_SIGNO=13

STATUS:
2014-12-03: As nearly I can tell, the Itead Joystick shield cannot be
used with the SAMA5D3-Xplained. I believe that the EMAC PHY chip is
enableed and since it shares pins with the Joystick, it interferes with
the Joystick inputs. There is probably more wrong than this; perhaps I
am not setting up the pins correctly. But having seen the states of the
button output pins change when powering up the board, I have lost hope
of getting the shield to work on this board. I leave the
implementation in place only for reference.

SAMA5D3-Xplained Configuration Options
=================================

CONFIG_ARCH - Identifies the arch/ subdirectory. This should
be set to:

CONFIG_ARCH="arm"

CONFIG_ARCH_family - For use in C code:

CONFIG_ARCH_ARM=y

CONFIG_ARCH_architecture - For use in C code:

CONFIG_ARCH_CORTEXA5=y

CONFIG_ARCH_CHIP - Identifies the arch/*/chip subdirectory

CONFIG_ARCH_CHIP="sama5"

CONFIG_ARCH_CHIP_name - For use in C code to identify the exact
chip:

CONFIG_ARCH_CHIP_SAMA5=y

and one of:

CONFIG_ARCH_CHIP_ATSAMA5D31=y
CONFIG_ARCH_CHIP_ATSAMA5D33=y
CONFIG_ARCH_CHIP_ATSAMA5D34=y
CONFIG_ARCH_CHIP_ATSAMA5D35=y

CONFIG_ARCH_BOARD - Identifies the configs subdirectory and
hence, the board that supports the particular chip or SoC.

CONFIG_ARCH_BOARD="sama5d3-xplained" (for the SAMA5D3-Xplained development board)

CONFIG_ARCH_BOARD_name - For use in C code

CONFIG_ARCH_BOARD_SAMA5D3_XPLAINED=y

CONFIG_ARCH_LOOPSPERMSEC - Must be calibrated for correct operation
of delay loops

CONFIG_ENDIAN_BIG - define if big endian (default is little
endian)

CONFIG_RAM_SIZE - Describes the installed DRAM (SRAM in this case):

CONFIG_RAM_SIZE=0x0002000 (128Kb)

CONFIG_RAM_START - The physical start address of installed DRAM

CONFIG_RAM_START=0x20000000

CONFIG_RAM_VSTART - The virutal start address of installed DRAM

CONFIG_RAM_VSTART=0x20000000

CONFIG_ARCH_LEDS - Use LEDs to show state. Unique to boards that
have LEDs

CONFIG_ARCH_INTERRUPTSTACK - This architecture supports an interrupt
stack. If defined, this symbol is the size of the interrupt
stack in bytes. If not defined, the user task stacks will be
used during interrupt handling.

CONFIG_ARCH_STACKDUMP - Do stack dumps after assertions

CONFIG_ARCH_LEDS - Use LEDs to show state. Unique to board architecture.

Individual subsystems can be enabled:

CONFIG_SAMA5_DBGU - Debug Unit
CONFIG_SAMA5_PIT - Periodic Interval Timer
CONFIG_SAMA5_WDT - Watchdog timer
CONFIG_SAMA5_HSMC - Multi-bit ECC
CONFIG_SAMA5_SMD - SMD Soft Modem
CONFIG_SAMA5_USART0 - USART 0
CONFIG_SAMA5_USART1 - USART 1
CONFIG_SAMA5_USART2 - USART 2
CONFIG_SAMA5_USART3 - USART 3
CONFIG_SAMA5_UART0 - UART 0
CONFIG_SAMA5_UART1 - UART 1
CONFIG_SAMA5_TWI0 - Two-Wire Interface 0
CONFIG_SAMA5_TWI1 - Two-Wire Interface 1
CONFIG_SAMA5_TWI2 - Two-Wire Interface 2
CONFIG_SAMA5_HSMCI0 - High Speed Multimedia Card Interface 0
CONFIG_SAMA5_HSMCI1 - High Speed Multimedia Card Interface 1
CONFIG_SAMA5_HSMCI2 - High Speed Multimedia Card Interface 2
CONFIG_SAMA5_SPI0 - Serial Peripheral Interface 0
CONFIG_SAMA5_SPI1 - Serial Peripheral Interface 1
CONFIG_SAMA5_TC0 - Timer Counter 0 (ch. 0, 1, 2)
CONFIG_SAMA5_TC1 - Timer Counter 1 (ch. 3, 4, 5)
CONFIG_SAMA5_PWM - Pulse Width Modulation Controller
CONFIG_SAMA5_ADC - Touch Screen ADC Controller
CONFIG_SAMA5_DMAC0 - DMA Controller 0
CONFIG_SAMA5_DMAC1 - DMA Controller 1
CONFIG_SAMA5_UHPHS - USB Host High Speed
CONFIG_SAMA5_UDPHS - USB Device High Speed
CONFIG_SAMA5_GMAC - Gigabit Ethernet MAC
CONFIG_SAMA5_EMACA - Ethernet MAC (type A)
CONFIG_SAMA5_LCDC - LCD Controller
CONFIG_SAMA5_ISI - Image Sensor Interface
CONFIG_SAMA5_SSC0 - Synchronous Serial Controller 0
CONFIG_SAMA5_SSC1 - Synchronous Serial Controller 1
CONFIG_SAMA5_CAN0 - CAN controller 0
CONFIG_SAMA5_CAN1 - CAN controller 1
CONFIG_SAMA5_SHA - Secure Hash Algorithm
CONFIG_SAMA5_AES - Advanced Encryption Standard
CONFIG_SAMA5_TDES - Triple Data Encryption Standard
CONFIG_SAMA5_TRNG - True Random Number Generator
CONFIG_SAMA5_ARM - Performance Monitor Unit
CONFIG_SAMA5_FUSE - Fuse Controller
CONFIG_SAMA5_MPDDRC - MPDDR controller

Some subsystems can be configured to operate in different ways. The drivers
need to know how to configure the subsystem.

CONFIG_SAMA5_PIOA_IRQ - Support PIOA interrupts
CONFIG_SAMA5_PIOB_IRQ - Support PIOB interrupts
CONFIG_SAMA5_PIOC_IRQ - Support PIOD interrupts
CONFIG_SAMA5_PIOD_IRQ - Support PIOD interrupts
CONFIG_SAMA5_PIOE_IRQ - Support PIOE interrupts

CONFIG_USART0_SERIALDRIVER - USART0 is configured as a UART
CONFIG_USART1_SERIALDRIVER - USART1 is configured as a UART
CONFIG_USART2_SERIALDRIVER - USART2 is configured as a UART
CONFIG_USART3_SERIALDRIVER - USART3 is configured as a UART

AT91SAMA5 specific device driver settings

CONFIG_SAMA5_DBGU_SERIAL_CONSOLE - selects the DBGU
for the console and ttyDBGU
CONFIG_SAMA5_DBGU_RXBUFSIZE - Characters are buffered as received.
This specific the size of the receive buffer
CONFIG_SAMA5_DBGU_TXBUFSIZE - Characters are buffered before
being sent. This specific the size of the transmit buffer
CONFIG_SAMA5_DBGU_BAUD - The configure BAUD of the DBGU.
CONFIG_SAMA5_DBGU_PARITY - 0=no parity, 1=odd parity, 2=even parity

CONFIG_U[S]ARTn_SERIAL_CONSOLE - selects the USARTn (n=0,1,2,3) or UART
m (m=4,5) for the console and ttys0 (default is the DBGU).
CONFIG_U[S]ARTn_RXBUFSIZE - Characters are buffered as received.
This specific the size of the receive buffer
CONFIG_U[S]ARTn_TXBUFSIZE - Characters are buffered before
being sent. This specific the size of the transmit buffer
CONFIG_U[S]ARTn_BAUD - The configure BAUD of the UART. Must be
CONFIG_U[S]ARTn_BITS - The number of bits. Must be either 7 or 8.
CONFIG_U[S]ARTn_PARITY - 0=no parity, 1=odd parity, 2=even parity
CONFIG_U[S]ARTn_2STOP - Two stop bits

AT91SAMA5 USB Host Configuration
Pre-requisites

CONFIG_USBDEV - Enable USB device support
CONFIG_USBHOST - Enable USB host support
CONFIG_SAMA5_UHPHS - Needed
CONFIG_SAMA5_OHCI - Enable the STM32 USB OTG FS block
CONFIG_SCHED_WORKQUEUE - Worker thread support is required

Options:

CONFIG_SAMA5_OHCI_NEDS
Number of endpoint descriptors
CONFIG_SAMA5_OHCI_NTDS
Number of transfer descriptors
CONFIG_SAMA5_OHCI_TDBUFFERS
Number of transfer descriptor buffers
CONFIG_SAMA5_OHCI_TDBUFSIZE
Size of one transfer descriptor buffer
CONFIG_USBHOST_INT_DISABLE
Disable interrupt endpoint support
CONFIG_USBHOST_ISOC_DISABLE
Disable isochronous endpoint support
CONFIG_USBHOST_BULK_DISABLE
Disable bulk endpoint support

config SAMA5_OHCI_REGDEBUG

Configurations
==============

Information Common to All Configurations
----------------------------------------
Each SAMA5D3-Xplained configuration is maintained in a sub-directory and
can be selected as follow:

tools/configure.sh sama5d3-xplained/<subdir>

Before building, make sure that the PATH environment variable include the
correct path to the directory than holds your toolchain binaries.

And then build NuttX by simply typing the following. At the conclusion of
the make, the nuttx binary will reside in an ELF file called, simply, nuttx.

make

The <subdir> that is provided above as an argument to the tools/configure.sh
must be is one of the following.

NOTES:

1. These configurations use the mconf-based configuration tool. To
change any of these configurations using that tool, you should:

a. Build and install the kconfig-mconf tool. See nuttx/README.txt
see additional README.txt files in the NuttX tools repository.

b. Execute 'make menuconfig' in nuttx/ in order to start the
reconfiguration process.

2. Unless stated otherwise, all configurations generate console
output on the DBGU (J23).

3. All of these configurations use the Code Sourcery for Windows toolchain
(unless stated otherwise in the description of the configuration). That
toolchain selection can easily be reconfigured using 'make menuconfig'.
Here are the relevant current settings:

Build Setup:
CONFIG_HOST_WINDOWS=y : Microsoft Windows
CONFIG_WINDOWS_CYGWIN=y : Using Cygwin or other POSIX environment

System Type -> Toolchain:
CONFIG_ARMV7A_TOOLCHAIN_GNU_EABIW=y : GNU EABI toolchain for windows

That same configuration will work with Atmel GCC toolchain. The only
change required to use the Atmel GCC toolchain is to change the PATH
variable so that those tools are selected instead of the CodeSourcery
tools. Try 'which arm-none-eabi-gcc' to make sure that you are
selecting the right tool.

See also the "NOTE about Windows native toolchains" in the section call
"GNU Toolchain Options" above.

!!!WARNING!!! The first time that you type 'make', the system will
configure itself based on the settings in the .config file. One of
these settings can cause a lot of confusion if you configure the build
in the wrong state: If you are running on Linux, make *certain* that
you have CONFIG_HOST_LINUX=y *before* the first make or you will
create a very corrupt configuration that may not be easy to recover
from.

4. The SAMA5Dx is running at 396MHz by default in these configurations.
This is because the original timing for the PLLs, NOR FLASH, and SDRAM
came from the Atmel NoOS sample code which runs at that rate.

The SAMA5Dx is capable of running at 528MHz, however, and is easily
re-configured:

Board Selection -> CPU Frequency
CONFIG_SAMA5D3xEK_396MHZ=n # Disable 396MHz operation
CONFIG_SAMA5D3xEK_528MHZ=y # Enable 528MHz operation

If you switch to 528MHz, you should also check the loop calibration
value in your .config file. Of course, it would be best to re-calibrate
the timing loop, but these values should get you in the ballpark:

CONFIG_BOARD_LOOPSPERMSEC=49341 # Calibrated on SAMA5D3-EK at 396MHz
# running from ISRAM
CONFIG_BOARD_LOOPSPERMSEC=65775 # Calibrated on SAMA4D3-Xplained at
# 528MHz running from SDRAM

Operation at 528MHz has been verified but is not the default in these
configurations because most testing was done at 396MHz. NAND has not
been verified at these rates.

Configuration Sub-directories
-----------------------------
Summary: Some of the descriptions below are long and wordy. Here is the
concise summary of the available SAMA5D3-Xplained configurations:

bridge: This is a simple testing that exercises EMAC and GMAC for
a simple UDP relay bridge test.
nsh: This is another NSH configuration, not too different from the
demo configuration. The nsh configuration is, however, bare bones.
It is the simplest possible NSH configuration and is useful as a
platform for debugging and integrating new features in isolation.

There may be issues with some of these configurations. See the details
before of the status of individual configurations.

Now for the gory details:

bridge:

This is a simple testing that exercises EMAC and GEMAC for a simple
UDP relay bridge test using apps/examples/bridge. See
apps/examples/README.txt for more information about this test.

NOTES:

1. This configuration uses the default DBGU serial console. That
is easily changed by reconfiguring to (1) enable a different
serial peripheral, and (2) selecting that serial peripheral as
the console device.

2. By default, this configuration is set up to build on Windows
under either a Cygwin or MSYS environment using a recent, Windows-
native, generic ARM EABI GCC toolchain (such as the CodeSourcery
toolchain). Both the build environment and the toolchain
selection can easily be changed by reconfiguring:

CONFIG_HOST_WINDOWS=y : Windows operating system
CONFIG_WINDOWS_CYGWIN=y : POSIX environment under windows
CONFIG_ARMV7A_TOOLCHAIN_CODESOURCERYW=y : CodeSourcery for Windows

If you are running on Linux, make *certain* that you have
CONFIG_HOST_LINUX=y *before* the first make or you will create a
corrupt configuration that may not be easy to recover from. See
the warning in the section "Information Common to All Configurations"
for further information.

3. This configuration executes out of SDRAM flash and is loaded into
SDRAM from NAND, Serial DataFlash, SD card or from a TFTPC sever via
U-Boot or BareBox. Data also is positioned in SDRAM.

I did most testing with nuttx.bin on an SD card. These are the
commands that I used to boot NuttX from the SD card:

U-Boot> fatload mmc 0 0x20008000 nuttx.bin
U-Boot> go 0x20008040

4. You will almost certainly need to adapt this configuration to
work in your network environment. I did all testing with a
single 10.0.0.xx network and a 4+1 port switch:

- Host PC IP 10.0.0.1
- Target GMAC IP: 10.0.0.2
- Target EMAC IP: 10.0.0.3

Host PC, EMAC, and GMAC were all connected using an Ethernet
switch to the same 255.255.255.0 network.

STATUS:

2014-11-20: Configuration created. Partially verified. Both the
EMAC and GMAC appear to be function; both respond to pings from
the host PC. But I cannot perform the full bridge test yet
because there still is no host-side test driver in apps/examples/bridge.
2014-11-21: Added the host-side test driver and correct a number
of errors in the test logic. The testing is working (according
to WireShark), but I an having some procedural issues related to
the Windows firewall.

nsh:

This configuration directory provide the NuttShell (NSH). There are
two NSH configurations: nsh and demo. The difference is that nsh is
intended to be a very simple NSH configuration upon which you can build
further functionality. The demo configuration, on the other hand, is
intended to be a rich configuration that shows many features all working
together.

NOTES:
1. This configuration uses the default DBGU serial console. That
is easily changed by reconfiguring to (1) enable a different
serial peripheral, and (2) selecting that serial peripheral as
the console device.

CONFIG_HOST_WINDOWS=y : Windows operating system
CONFIG_WINDOWS_CYGWIN=y : POSIX environment under windows
CONFIG_ARMV7A_TOOLCHAIN_CODESOURCERYW=y : CodeSourcery for Windows

3. This configuration executes out of SDRAM flash and is loaded into
SDRAM from NAND, Serial DataFlash, SD card or from a TFTPC sever via
U-Boot or BareBox. Data also is positioned in SDRAM.

I did most testing with nuttx.bin on an SD card. These are the
commands that I used to boot NuttX from the SD card:

U-Boot> fatload mmc 0 0x20008000 nuttx.bin
U-Boot> go 0x20008040

4. This configuration has support for NSH built-in applications enabled.
However, no built-in applications are selected in the base configuration.

5. This configuration has support for the FAT file system built in. However,
by default, there are no block drivers initialized. The FAT file system can
still be used to create RAM disks.

6. The SAMA5D3 Xplained board includes an option serial DataFlash. Support
for that serial FLASH can be enabled by modifying the NuttX configuration
as described above in the paragraph entitled "AT25 Serial FLASH".

7. Enabling HSMCI support. The SAMA5D3-Xplained provides a two SD memory
card slots: (1) a full size SD card slot (J10), and (2) a microSD
memory card slot (J11). The full size SD card slot connects via HSMCI0;
the microSD connects vi HSMCI1. Support for both SD slots can be enabled
with the settings provided in the paragraph entitled "HSMCI Card Slots"
above.

8. Support the USB low-, high- and full-speed OHCI host driver can be enabled
by changing the NuttX configuration file as described in the section
entitled "USB High-Speed Host" above.

9. Support the USB high-speed USB device driver (UDPHS) can be enabled
by changing the NuttX configuration file as described above in the
section entitled "USB High-Speed Device."

10. I2C Tool. NuttX supports an I2C tool at apps/system/i2c that can be
used to peek and poke I2C devices. See the discussion above under
"I2C Tool" for detailed configuration settings.

11. Networking support via the can be added to NSH by modifying the
configuration. See the "Networking" section above for detailed
configuration settings.

12. The Real Time Clock/Calendar (RTC) may be enabled by reconfiguring NuttX.
See the section entitled "RTC" above for detailed configuration settings.

13. This example can be configured to exercise the watchdog timer test
(apps/examples/watchdog). See the detailed configuration settings in
the section entitled "Watchdog Timer" above.

14. This example can be configured to enable the SAMA5 TRNG peripheral so
that it provides /dev/random. See the section entitled "TRNG and
/dev/random" above for detailed configuration information.

16. See also the sections above for additional configuration options:
"CAN Usage", "SAMA5 ADC Support", "SAMA5 PWM Support", "I2S Audio
Support"

STATUS:
See the To-Do list below

2014-4-3: Delay loop calibrated: CONFIG_BOARD_LOOPSPERMSEC=65775

To-Do List
==========

1) Neither USB OHCI nor EHCI support Isochronous endpoints. Interrupt
endpoint support in the EHCI driver is untested (but works in similar
EHCI drivers).

2) HSCMI. CONFIG_MMCSD_MULTIBLOCK_DISABLE=y is set to disable multi-block
transfers because of some issues that I saw during testing. The is very
low priority to me but might be important to you if you are need very
high performance SD card accesses.

HSMCI TX DMA is currently disabled for the SAMA5D3. There is some
issue with the TX DMA setup (HSMCI TX DMA the same driver works with
the SAMA5D4 which has a different DMA subsystem). This is a bug that
needs to be resolved.

UPDATE: This problem may be fixed with a bug correct on 2015-03-15).
Need to retest. That change is necessary, but may not be sufficient to
solve the problem.

3) GMAC has only been tested on a 10/100Base-T network. I don't have a
1000Base-T network to support additional testing.

4) Some drivers may require some adjustments if you intend to run from SDRAM.
That is because in this case macros like BOARD_MCK_FREQUENCY are not constants
but are instead function calls: The MCK clock frequency is not known in
advance but instead has to be calculated from the bootloader PLL configuration.

As of this writing, all drivers have been converted to run from SDRAM except
for the PWM and the Timer/Counter drivers. These drivers use the
BOARD_MCK_FREQUENCY definition in more complex ways and will require some
minor redesign and re-testing before they can be available.