incubator-nuttx

History

chao.an b88561299b make/expression: improving up asm/C/C++ compile times In the current compilation environment, the recursive assignment(=) for compile flags will be delayed until every file is actually need to be compile. For example: -------------------------------------------------------------------------------- arch/arm/src/Makefile: INCLUDES += ${shell $(INCDIR) "$(CC)" $(ARCH_SRCDIR)$(DELIM)chip} INCLUDES += ${shell $(INCDIR) "$(CC)" $(ARCH_SRCDIR)$(DELIM)common} INCLUDES += ${shell $(INCDIR) "$(CC)" $(ARCH_SRCDIR)$(DELIM)$(ARCH_SUBDIR)} INCLUDES += ${shell $(INCDIR) "$(CC)" $(TOPDIR)$(DELIM)sched} CPPFLAGS += $(INCLUDES) $(EXTRAFLAGS) CFLAGS += $(INCLUDES) $(EXTRAFLAGS) CXXFLAGS += $(INCLUDES) $(EXTRAFLAGS) AFLAGS += $(INCLUDES) $(EXTRAFLAGS) -------------------------------------------------------------------------------- All compilation options will be included recursively, which will be delayed until the compilation options are actually used: tools/Config.mk: -------------------------------------------------------------------------------- define COMPILE @echo "CC: $1" $(Q) $(CC) -c $(CFLAGS) $($(strip $1)_CFLAGS) $1 -o $2 endef -------------------------------------------------------------------------------- All compile flags to be reexecuted $(INCDIR) as long as one file needs to be compiled, but in fact, the compilation options have not changed in the current directory. So the we recommand to change the syntax of assignment From Recursive (=) To Simple (:=) In this way, we can ensure that all compilation options are expanded only once and reducing repeated works. Signed-off-by: chao.an <anchao@xiaomi.com>		2020-11-02 07:53:53 -08:00
..
configs	libc/stdio: Allocate file_struct dynamically	2020-09-11 17:58:17 +08:00
include	Merged in alinjerpelea/nuttx (pull request #969 )	2019-08-08 14:53:04 +00:00
scripts	make/expression: improving up asm/C/C++ compile times	2020-11-02 07:53:53 -08:00
src	board: Let avr/renesas utilize boards/Board.mk	2020-07-19 19:40:32 -07:00
Kconfig	…
README.txt	…

README.txt

README
======

  This is the README file for the port of NuttX to the Arduino Mega 2560 Rev3.

    https://www.arduino.cc/en/Main/ArduinoBoardMega2560

  The board is based on ATMega2560 chip from Atmel

  http://www.atmel.com/devices/atmega2560.aspx

Contents
========

  o Toolchain
  o Serial Console
  o Configurations

Toolchain
=========

  Right now only Atmel's AVR8 Toolchain is supported. You can get it from

    http://www.atmel.com/tools/atmelavrtoolchainforwindows.aspx

  It is basically WinAVR compatible so sub-projects may define WinAVR as a
  tool-chain but specify path to the Atmel AVR8 in path. See
  arduino-mega2560/hello for example.

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

  The serial console is available on USART0.  You will need to connect an
  RS-232 shield or an external RS-232 driver as follows:

    TXD: TX0->1
    RXD: RX0->0
    GND: Power GND
    +5V: Power +5V

  You will then need to use a terminal program configured at 38400 8N1.

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

  Common Configuration Notes
  --------------------------
  1. Each Arduino MEGA2560 configuration is maintained in a sub-directory
     and can be selected as follow:

       tools/configure.sh arduino-mega2560:<subdir>

     Where <subdir> is one of the configuration sub-directories described in
     the following paragraph.

  2. These configurations use the mconf-based configuration tool.  To
     change a 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.

  3. By default, all configurations assume the Atmel Studio AVR8 toolchain
     under Cygwin with Windows.  This is easily reconfigured:

        CONFIG_HOST_WINDOWS=y
        CONFIG_WINDOWS_CYGWIN=y
        CONFIG_AVR_BUILDROOT_TOOLCHAIN=y

  Configuration Sub-Directories
  -----------------------------
  hello:
    The simple apps/examples/hello "Hello, World!" example.

  nsh:
    This is a reduce NuttShell (NSH) configuration using apps/example/nsh.
    The serial console is provided on USART0 and can be accessed via
    an external RS-232 driver as described above under "Serial Console".

    NOTES:

    1. As of 2015-01-16, the default static memory usage is:

         $ size nuttx.elf
          text    data     bss     dec     hex filename
         34348    2117     944   37409    9221 nuttx.elf

       And dynamic, heap usage:

         nsh> free
                      total       used       free    largest
         Mem:          4736       1768       2968       2968

       There is plenty of FLASH space but not a lot of free SRAM. This
       SRAM usage is due primarily to constant strings defined by NSH.

       NOTE: I investigated the possibility of adding IPTR/IOBJ
       qualifiers in the NSH library and moving the strings to FLASH.
       This is still a possibility but would requires some extensive
       changes to NSH.