incubator-nuttx/configs/kwikstik-k40
Gregory Nutt 32b4a48e7a Misc changes from Richard Cochran 2014-01-15 11:05:15 -06:00
..
include Remove executable property from source and make files 2012-09-13 18:46:10 +00:00
ostest Misc changes from Richard Cochran 2014-01-15 11:05:15 -06:00
scripts Missed a few ld.script files in Freddie Chopin's last big change 2012-11-04 19:12:12 +00:00
src Move apps/examples/usbmsc to apps/system/usbmsc 2013-09-25 16:54:39 -06:00
Kconfig Kconfig: Standardize board LED and button configurations 2012-09-08 03:31:46 +00:00
README.txt Finally... renamed all CONFIG_DRAM_ settings to CONFIG_RAM_ 2013-07-26 10:09:17 -06:00

README.txt

README.txt
==========

This is the README file for the port of NuttX to the Freescale Kinetis
KwiStick K40.  Refer to the Freescale web site for further information
about this part:
http://www.freescale.com/webapp/sps/site/prod_summary.jsp?code=KWIKSTIK-K40

The Kwikstik is used with the FreeScale Tower System (mostly just to
provide a simple UART connection)

Contents
========

  o Kinetis KwikStik-K40 Features
  o Kinetis KwikStik-K60 Pin Configuration
    - On-Board Connections
    - Connections via the General Purpose Tower Plug-in (TWRPI) Socket
    - Connections via the Tower Primary Connector Side A
    - Connections via the Tower Primary Connector Side B
    - TWR-SER Serial Board Connection
  o Development Environment
  o GNU Toolchain Options
  o IDEs
  o NuttX EABI "buildroot" Toolchain
  o NuttX OABI "buildroot" Toolchain
  o NXFLAT Toolchain
  
Kinetis KwikStik-K40 Features:
==============================

  o Kinetis K40 MCU in 144 LQFP
    - 100 MHz ARM Cortex-M4 core
    - 256Kb program flash, 256Kb FlexMemory
    - Full-speed USB 2.0 device
    - Low-pwer segment LCD controller
    - SPI, UART, CAN and more
  o Large segment LCD display with 306 segments
  o 2.3mm audio output and 2 micro USB connectors
  o Omnidirectional microphone and a buzzer
  o On-board Segger J-Link debugger interface
  o Infrared communication port
  o microSD card slot
  o Capacitive touch sensing interface
  o Freescale Tower System connectivity for UART, timers, CAN, SPI, I2C, and DAC
  o Freescale Tower plug-in (TWRPI) socket connectivity for ADC, SPI, I2C, and GPIO

Kinetis KwikStik-K40 Pin Configuration
======================================

On-Board Connections
------------------- -------------------------- -------- -------------------
FEATURE             CONNECTION                 PORT/PIN PIN FUNCTION
------------------- -------------------------- -------- -------------------
Audio Jack Output   Audio Amp On               PTE28    PTE28
                    Audio Output               DAC1_OUT DAC1_OUT
                    Volume Up                  PTD10    PTD10
                    Volume Down                PTD11    PTD11
Buzzer              Audio Out                  PTA8     FTM1_CH0
Microphone          Microphone input           PTA7     ADC0_SE10
SD Card Slot        SD Clock                   PTE2     SDHC0_DCLK
                    SD Command                 PTE3     SDHC0_CMD
                    SD Data0                   PTD12    SDHC0_D4
                    SD Data1                   PTD13    SDHC0_D5
                    SD Data2                   PTD14    SDHC0_D6
                    SD Data3                   PTD15    SDHC0_D7
                    SD Card Detect             PTE27    PTE27
                    SD Card On                 PTE6     PTE6
Infrared Port       IR Transmit                PTE4     IR_TX
                    IR Receive                 PTA13    CMP2_IN0
Touch Pads          E1 / Touch                 PTB0     TSI0_CH0
                    E2 / Touch                 PTA4     TSI0_CH5
                    E3 / Touch                 PTA24    PTA24
                    E4 / Touch                 PTA25    PTA25
                    E5 / Touch                 PTA26    PTA26
                    E6 / Touch                 PTA27    PTA27

Connections via the General Purpose Tower Plug-in (TWRPI) Socket
------------------- -------------------------- -------- -------------------
FEATURE             CONNECTION                 PORT/PIN PIN FUNCTION
------------------- -------------------------- -------- -------------------
General Purpose     TWRPI AN0 (J8 Pin 8)       ?        ADC0_DP0/ADC1_DP3
TWRPI Socket        TWRPI AN1 (J8 Pin 9)       ?        ADC0_DM0/ADC1_DM3
                    TWRPI AN2 (J8 Pin 12)      ?        ADC1_DP0/ADC0_DP3
                    TWRPI ID0 (J8 Pin 17)      ?        ADC0_DP1
                    TWRPI ID1 (J8 Pin 18)      ?        ADC0_DM1
                    TWRPI I2C SCL (J9 Pin 3)   PTC10    I2C1_SCL
                    TWRPI I2C SDA (J9 Pin 4)   PTC11    I2C1_SDA
                    TWRPI SPI MISO (J9 Pin 9)  PTB23    SPI2_SIN
                    TWRPI SPI MOSI (J9 Pin 10) PTB22    SPI2_SOUT
                    TWRPI SPI SS (J9 Pin 11)   PTB20    SPI2_PCS0
                    TWRPI SPI CLK (J9 Pin 12)  PTB21    SPI2_SCK
                    TWRPI GPIO0 (J9 Pin 15)    PTC12    PTC12
                    TWRPI GPIO1 (J9 Pin 16)    PTB9     PTB9
                    TWRPI GPIO2 (J9 Pin 17)    PTB10    PTB10
                    TWRPI GPIO3 (J9 Pin 18)    PTC5     PTC5
                    TWRPI GPIO4 (J9 Pin 19)    PTA5     PTA5

The KwikStik features an expansion card-edge connector that interfaces to the Primary Elevator board in a Tower system (Primary side).

Connections via the Tower Primary Connector Side A
--- -------------------- --------------------------------
PIN NAME                 USAGE
--- -------------------- --------------------------------
A9  GPIO9 / CTS1         PTE10/UART_CTS
A43 RXD1                 PTE9/UART_RX
A44 TXD1                 PTE8/UART_TX
A63 RSTOUT_b             PTA9/FTM1_CH1

Connections via the Tower Primary Connector Side B
--- -------------------- --------------------------------
PIN NAME                 USAGE
--- -------------------- --------------------------------
B21 GPIO1 / RTS1         PTE7/UART_RTS
B37 PWM7                 PTA8/FTM1_CH0
B38 PWM6                 PTA9/FTM1_CH1
B41 CANRX0               PTE25/CAN1_RX
B42 CANTX0               PTE24/CAN1_TX
B44 SPI0_MISO            PTA17/SPI0_SIN
B45 SPI0_MOSI            PTA16/SPI0_SOUT
B46 SPI0_CS0_b           PTA14/SPI0_PCS0
B48 SPI0_CLK             PTA15/SPI0_SCK
B50 SCL1                 PTE1/I2C1_SCL
B51 SDA1                 PTE0/I2C1_SDA
B52 GPIO5 / SD_CARD_DET  PTA16

TWR-SER Serial Board Connection
===============================

The serial board connects into the tower and then maps to the tower pins to
yet other functions (see TWR-SER.pdf).

For the serial port, the following jumpers are required:

  J15: 1-2 (default)
  J17: 1-2 (default)
  J18: 1-2 (default)
  J19: 1-2 (default)

The two connections map as follows:

  A41 RXD0  - Not connected
  A42 TXD0  - Not connected
  A43 RXD1  - ELE_RXD (connects indirectory to DB-9 connector J8)
  A44 TXD1  - ELE_TXD (connects indirectory to DB-9 connector J8)

Finally, we can conclude that

  UART5 (PTE8/9) is associated with the DB9 connector

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

  Either Linux or Cygwin on Windows can be used for the development environment.
  The source has been built only using the GNU toolchain (see below).  Other
  toolchains will likely cause problems. Testing was performed using the Cygwin
  environment.

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

  The NuttX make system has been modified to support the following different
  toolchain options.

  1. The CodeSourcery GNU toolchain,
  2. The devkitARM GNU toolchain,
  3. The NuttX buildroot Toolchain (see below).

  All testing has been conducted using the CodeSourcery Windows toolchain.  To
  use the devkitARM or the NuttX GNU toolchain, you simply need to change the
  the following configuration options to your .config (or defconfig) file:

    CONFIG_KINETIS_CODESOURCERYW=y  : CodeSourcery under Windows
    CONFIG_KINETIS_CODESOURCERYL=y  : CodeSourcery under Linux
    CONFIG_KINETIS_DEVKITARM=y      : devkitARM under Windows
    CONFIG_KINETIS_BUILDROOT=y      : NuttX buildroot under Linux or Cygwin (default)

  If you are not using CONFIG_KINETIS_BUILDROOT, then you may also have to modify
  the PATH in the setenv.h file if your make cannot find the tools.

  NOTE: the CodeSourcery (for Windows) and devkitARM toolchains are
  Windows native toolchains.  The CodeSourcey (for Linux) and NuttX buildroot
  toolchains are Cygwin and/or Linux 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.

  3. Dependencies are not made when using Windows versions of the GCC.  This is
     because the dependencies are generated using Windows pathes which do not
     work with the Cygwin make.

       MKDEP                = $(TOPDIR)/tools/mknulldeps.sh

  NOTE 1: The CodeSourcery toolchain (2009q1) does not work with default optimization
  level of -Os (See Make.defs).  It will work with -O0, -O1, or -O2, but not with
  -Os.

  NOTE 2: The devkitARM toolchain includes a version of MSYS make.  Make sure that
  the paths to Cygwin's /bin and /usr/bin directories appear BEFORE the devkitARM
  path or will get the wrong version of make.

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/k40,
     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/kinetis/k40_vectors.S.

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

  A GNU GCC-based toolchain is assumed.  The files */setenv.sh should
  be modified to point to the correct path to the Cortex-M4 GCC toolchain (if
  different from the default in your PATH variable).

  If you have no Cortex-M4 toolchain, one can be downloaded from the NuttX
  SourceForge download site (https://sourceforge.net/projects/nuttx/files/buildroot/).
  This GNU toolchain builds and executes in the Linux or Cygwin environment.

  NOTE:  The NuttX toolchain may not include optimizations for Cortex-M4 (ARMv7E-M).

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

     cd tools
     ./configure.sh kwikstik-k40/<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-eabi-defconfig-4.6.3 .config

  6. make oldconfig

  7. make

  8. Edit setenv.h, if necessary, so 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-M4 toolchain for Cygwin under Windows.

  NOTE:  Unfortunately, the 4.6.3 EABI toolchain is not compatible with the
  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; instead use the GCC 4.3.3 OABI toolchain.
  See instructions below.

NuttX OABI "buildroot" Toolchain
================================

  The older, OABI buildroot toolchain is also available.  To use the OABI
  toolchain:

  1. When building the buildroot toolchain, either (1) modify the cortexm3-eabi-defconfig-4.6.3
     configuration to use EABI (using 'make menuconfig'), or (2) use an exising OABI
     configuration such as cortexm3-defconfig-4.3.3

  2. Modify the Make.defs file to use the OABI conventions:

    +CROSSDEV = arm-nuttx-elf-
    +ARCHCPUFLAGS = -mtune=cortex-m3 -march=armv7-m -mfloat-abi=soft
    +NXFLATLDFLAGS2 = $(NXFLATLDFLAGS1) -T$(TOPDIR)/binfmt/libnxflat/gnu-nxflat-gotoff.ld -no-check-sections
    -CROSSDEV = arm-nuttx-eabi-
    -ARCHCPUFLAGS = -mcpu=cortex-m3 -mthumb -mfloat-abi=soft
    -NXFLATLDFLAGS2 = $(NXFLATLDFLAGS1) -T$(TOPDIR)/binfmt/libnxflat/gnu-nxflat-pcrel.ld -no-check-sections

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 SourceForge download site
  (https://sourceforge.net/projects/nuttx/files/).
 
  This GNU toolchain builds and executes in the Linux or Cygwin environment.

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

     cd tools
     ./configure.sh lpcxpresso-lpc1768/<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. Edit setenv.h, if necessary, so that the PATH variable includes
     the path to the newly builtNXFLAT binaries.

KwikStik-K40-specific Configuration Options
============================================

    CONFIG_ARCH - Identifies the arch/ subdirectory.  This sould
       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_CORTEXM4=y

    CONFIG_ARCH_CHIP - Identifies the arch/*/chip subdirectory

       CONFIG_ARCH_CHIP=k40

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

       CONFIG_ARCH_CHIP_MK40X256VLQ100

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

       CONFIG_ARCH_BOARD=kwikstik-k40 (for the KwikStik-K40 development board)

    CONFIG_ARCH_BOARD_name - For use in C code

       CONFIG_ARCH_BOARD_KWIKSTIK_K40=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=0x00010000 (64Kb)

    CONFIG_RAM_START - The start address of installed DRAM

       CONFIG_RAM_START=0x20000000

    CONFIG_ARCH_IRQPRIO - The Kinetis K40 supports interrupt prioritization

       CONFIG_ARCH_IRQPRIO=y

    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.

    CONFIG_ARCH_CALIBRATION - Enables some build in instrumentation that
       cause a 100 second delay during boot-up.  This 100 second delay
       serves no purpose other than it allows you to calibratre
       CONFIG_ARCH_LOOPSPERMSEC.  You simply use a stop watch to measure
       the 100 second delay then adjust CONFIG_ARCH_LOOPSPERMSEC until
       the delay actually is 100 seconds.

  Individual subsystems can be enabled:

    CONFIG_KINETIS_TRACE    -- Enable trace clocking on power up.
    CONFIG_KINETIS_FLEXBUS  -- Enable flexbus clocking on power up.
    CONFIG_KINETIS_UART0    -- Support UART0
    CONFIG_KINETIS_UART1    -- Support UART1
    CONFIG_KINETIS_UART2    -- Support UART2
    CONFIG_KINETIS_UART3    -- Support UART3
    CONFIG_KINETIS_UART4    -- Support UART4
    CONFIG_KINETIS_UART5    -- Support UART5
    CONFIG_KINETIS_ENET     -- Support Ethernet (K60 only)
    CONFIG_KINETIS_RNGB     -- Support the random number generator(K60 only)
    CONFIG_KINETIS_FLEXCAN0 -- Support FlexCAN0
    CONFIG_KINETIS_FLEXCAN1 -- Support FlexCAN1
    CONFIG_KINETIS_SPI0     -- Support SPI0
    CONFIG_KINETIS_SPI1     -- Support SPI1
    CONFIG_KINETIS_SPI2     -- Support SPI2
    CONFIG_KINETIS_I2C0     -- Support I2C0
    CONFIG_KINETIS_I2C1     -- Support I2C1
    CONFIG_KINETIS_I2S      -- Support I2S
    CONFIG_KINETIS_DAC0     -- Support DAC0
    CONFIG_KINETIS_DAC1     -- Support DAC1
    CONFIG_KINETIS_ADC0     -- Support ADC0
    CONFIG_KINETIS_ADC1     -- Support ADC1
    CONFIG_KINETIS_CMP      -- Support CMP
    CONFIG_KINETIS_VREF     -- Support VREF
    CONFIG_KINETIS_SDHC     -- Support SD host controller
    CONFIG_KINETIS_FTM0     -- Support FlexTimer 0
    CONFIG_KINETIS_FTM1     -- Support FlexTimer 1
    CONFIG_KINETIS_FTM2     -- Support FlexTimer 2
    CONFIG_KINETIS_LPTIMER  -- Support the low power timer
    CONFIG_KINETIS_RTC      -- Support RTC
    CONFIG_KINETIS_SLCD     -- Support the segment LCD (K40 only)
    CONFIG_KINETIS_EWM      -- Support the external watchdog
    CONFIG_KINETIS_CMT      -- Support Carrier Modulator Transmitter
    CONFIG_KINETIS_USBOTG   -- Support USB OTG (see also CONFIG_USBHOST and CONFIG_USBDEV)
    CONFIG_KINETIS_USBDCD   -- Support the USB Device Charger Detection module
    CONFIG_KINETIS_LLWU     -- Support the Low Leakage Wake-Up Unit
    CONFIG_KINETIS_TSI      -- Support the touch screeen interface
    CONFIG_KINETIS_FTFL     -- Support FLASH
    CONFIG_KINETIS_DMA      -- Support DMA
    CONFIG_KINETIS_CRC      -- Support CRC
    CONFIG_KINETIS_PDB      -- Support the Programmable Delay Block
    CONFIG_KINETIS_PIT      -- Support Programmable Interval Timers
    CONFIG_ARMV7M_MPU       -- Support the MPU

  Kinetis interrupt priorities (Default is the mid priority)  These should
  not be set because they can cause unhandled, nested interrupts.  All
  interrupts need to be at the default priority in the current design.

    CONFIG_KINETIS_UART0PRIO
    CONFIG_KINETIS_UART1PRIO
    CONFIG_KINETIS_UART2PRIO
    CONFIG_KINETIS_UART3PRIO
    CONFIG_KINETIS_UART4PRIO
    CONFIG_KINETIS_UART5PRIO

    CONFIG_KINETIS_SDHC_PRIO

  PIN Interrupt Support

    CONFIG_GPIO_IRQ          -- Enable pin interrtup support.  Also needs
      one or more of the following:
    CONFIG_KINETIS_PORTAINTS -- Support 32 Port A interrupts
    CONFIG_KINETIS_PORTBINTS -- Support 32 Port B interrupts
    CONFIG_KINETIS_PORTCINTS -- Support 32 Port C interrupts
    CONFIG_KINETIS_PORTDINTS -- Support 32 Port D interrupts
    CONFIG_KINETIS_PORTEINTS -- Support 32 Port E interrupts

  Kinetis K40 specific device driver settings

    CONFIG_UARTn_SERIAL_CONSOLE - selects the UARTn (n=0..5) for the
      console and ttys0 (default is the UART0).
    CONFIG_UARTn_RXBUFSIZE - Characters are buffered as received.
       This specific the size of the receive buffer
    CONFIG_UARTn_TXBUFSIZE - Characters are buffered before
       being sent.  This specific the size of the transmit buffer
    CONFIG_UARTn_BAUD - The configure BAUD of the UART.
    CONFIG_UARTn_BITS - The number of bits.  Must be either 8 or 8.
    CONFIG_UARTn_PARTIY - 0=no parity, 1=odd parity, 2=even parity

  KwikStik-K40 LCD Hardware Configuration

    CONFIG_LCD_LANDSCAPE - Define for 320x240 display "landscape"
      support. Default is this 320x240 "landscape" orientation
      (this setting is informative only... not used).
    CONFIG_LCD_PORTRAIT - Define for 240x320 display "portrait"
      orientation support.  In this orientation, the KwikStik-K40's
      LCD ribbon cable is at the bottom of the display. Default is
      320x240 "landscape" orientation.
    CONFIG_LCD_RPORTRAIT - Define for 240x320 display "reverse
      portrait" orientation support.  In this orientation, the
      KwikStik-K40's LCD ribbon cable is at the top of the display.
      Default is 320x240 "landscape" orientation.
    CONFIG_LCD_BACKLIGHT - Define to support an adjustable backlight
      using timer 1.  The granularity of the settings is determined
      by CONFIG_LCD_MAXPOWER.  Requires CONFIG_KINETIS_TIM1.

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

Each KwikStik-K40 configuration is maintained in a sub-directory and
can be selected as follow:

    cd tools
    ./configure.sh kwikstik-k40/<subdir>
    cd -
    . ./setenv.sh

Where <subdir> is one of the following:

  ostest:
  ------
    This configuration directory, performs a simple OS test using
    examples/ostest.

    NOTES:

    1. This configuration uses the mconf-based configuration tool.  To
       change this configuration using that tool, you should:

       a. Build and install the kconfig-mconf tool.  See nuttx/README.txt
          and misc/tools/

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

    2. Default platform/toolchain:

       CONFIG_HOST_LINUX=y                 : Linux (Cygwin under Windows okay too).
       CONFIG_ARMV7M_TOOLCHAIN_BUILDROOT=y : Buildroot (arm-nuttx-elf-gcc)
       CONFIG_ARMV7M_OABI_TOOLCHAIN=y      : The older OABI version
       CONFIG_RAW_BINARY=y                 : Output formats: ELF and raw binary