170a86c4a5
Re-structure the AVR documentation to have pages for the chip families, and their own board listings.
107 lines
3.3 KiB
Text
107 lines
3.3 KiB
Text
README
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======
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This is the README file for the port of NuttX to the Arduino Mega 2560 Rev3.
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https://www.arduino.cc/en/Main/ArduinoBoardMega2560
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The board is based on ATMega2560 chip from Atmel
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http://www.atmel.com/devices/atmega2560.aspx
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Contents
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========
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o Toolchain
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o Serial Console
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o Configurations
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Toolchain
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=========
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Right now only Atmel's AVR8 Toolchain is supported. You can get it from
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http://www.atmel.com/tools/atmelavrtoolchainforwindows.aspx
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It is basically WinAVR compatible so sub-projects may define WinAVR as a
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tool-chain but specify path to the Atmel AVR8 in path. See
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arduino-mega2560/hello for example.
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Serial Console
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==============
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The serial console is available on USART0. You will need to connect an
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RS-232 shield or an external RS-232 driver as follows:
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TXD: TX0->1
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RXD: RX0->0
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GND: Power GND
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+5V: Power +5V
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You will then need to use a terminal program configured at 38400 8N1.
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Configurations
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==============
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Common Configuration Notes
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--------------------------
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1. Each Arduino MEGA2560 configuration is maintained in a sub-directory
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and can be selected as follow:
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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
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the following paragraph.
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2. These configurations use the mconf-based configuration tool. To
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change a configurations using that tool, you should:
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a. Build and install the kconfig-mconf tool. See nuttx/README.txt
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see additional README.txt files in the NuttX tools repository.
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b. Execute 'make menuconfig' in nuttx/ in order to start the
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reconfiguration process.
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3. By default, all configurations assume the Atmel Studio AVR8 toolchain
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under 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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4. Build with GCC disables CONFIG_DEBUG_OPT_UNUSED_SECTIONS by default.
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This is because the linker script was not checked to determine
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if it properly prevents removal of sections which the linker considers
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unreferenced but which must be present in the binary.
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Configuration Sub-Directories
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-----------------------------
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hello:
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The simple apps/examples/hello "Hello, World!" example.
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nsh:
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This is a reduce NuttShell (NSH) configuration using apps/example/nsh.
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The serial console is provided on USART0 and can be accessed via
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an external RS-232 driver as described above under "Serial Console".
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NOTES:
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1. As of 2015-01-16, the default static memory usage is:
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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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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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NOTE: I investigated the possibility of adding IPTR/IOBJ
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qualifiers in the NSH library and moving the strings to FLASH.
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This is still a possibility but would requires some extensive
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changes to NSH.
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