9897ef3cdb
Migrated legacy README.txt documentation to RST format. Signed-off-by: Matteo Golin <matteo.golin@gmail.com>
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2.5 KiB
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86 lines
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Arduino Mega2560
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.. tags:: chip:atmega2560, chip:atmega, vendor:arduino, arch:avr
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This is the documentation for the port of NuttX to the `Arduino Mega 2560 Rev3
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<https://www.arduino.cc/en/Main/ArduinoBoardMega2560>`_. The board is based on
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the `ATMega2560 chip from Atmel
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<http://www.atmel.com/devices/atmega2560.aspx>`_.
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.. figure:: arduino-mega2560.png
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:figwidth: 50%
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:align: center
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:alt: The Arduino ATMega2560 micro-controller board.
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The Arduino ATMega2560 micro-controller board.
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Toolchain
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=========
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To learn more about installing the required tool-chain, read the "Toolchain"
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section of :doc:`../../index`.
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Configurations
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==============
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Each Arduino MEGA2560 configuration is maintained in a sub-directory
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and can be selected as follow:
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.. code:: console
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$ tools/configure.sh arduino-mega2560:<subdir>
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Where ``<subdir>`` is one of the configuration sub-directories described in the
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following sub-headings.
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By default, all configurations assume the Atmel Studio AVR8 toolchain under
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Cygwin with Windows. This is easily reconfigured:
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* ``CONFIG_HOST_WINDOWS=y``
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* ``CONFIG_WINDOWS_CYGWIN=y``
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* ``CONFIG_AVR_BUILDROOT_TOOLCHAIN=y``
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Build with GCC disables ``CONFIG_DEBUG_OPT_UNUSED_SECTIONS`` by default. This is
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because the linker script was not checked to determine if it properly prevents
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removal of sections which the linker considers unreferenced but which must be
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present in the binary.
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hello
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-----
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The simple ``apps/examples/hello`` "Hello, World!" example. The output is
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displayed on UART0 at a baud rate of 38400, 8N1.
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nsh
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---
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This is a reduce NuttShell (NSH) configuration using ``apps/example/nsh``. The
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serial console is provided on USART0 and can be accessed via a serial terminal
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at a baud rate of 38400, 8N1.
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.. note::
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As of 2015-01-16, the default static memory usage is:
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.. code:: console
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$ size nuttx.elf
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text data bss dec hex filename
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34348 2117 944 37409 9221 nuttx.elf
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And dynamic, heap usage:
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.. code:: console
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nsh> free
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total used free largest
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Mem: 4736 1768 2968 2968
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There is plenty of FLASH space but not a lot of free SRAM. This
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SRAM usage is due primarily to constant strings defined by NSH.
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I investigated the possibility of adding IPTR/IOBJ qualifiers in the NSH
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library and moving the strings to FLASH. This is still a possibility but
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would require some extensive changes to NSH.
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