106 lines
2.9 KiB
ReStructuredText
106 lines
2.9 KiB
ReStructuredText
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.. include:: /substitutions.rst
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.. _running:
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Running
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=======
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Embedded boards have different ways to get your program onto them and get them running. This guide assumes your board
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has a JTAG connector, and you have a JTAG hardware debugger like a
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`Segger J-Link <https://www.segger.com/products/debug-probes/j-link/>`_. `JTAG <https://en.wikipedia.org/wiki/JTAG>`_
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is a set of standards that let you attach a hardware device to your embedded board, and then remotely control the CPU.
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You can load code, start, stop, step through the program, and examine variables and memory.
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#. Attach the Debugger Cables
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#. Start the Debugger
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Refer to your JTAG debugger's documentation for information on how to start a GDB Server process that gdb can
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communicate with to load code and start, stop, and step the embedded board's CPU. Your command line may be
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different from this one.
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.. code-block:: bash
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$ JLinkGDBServer -device ATSAMA5D27 -if JTAG -speed 1000 -JTAGConf -1,-1
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#. Launch the Gnu Debugger
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In another terminal window, launch the GDB for your platform. In the case of this guide, this came with the
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ARM Embedded Gnu Toolchain we downloaded in the Install step.
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.. code-block:: bash
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$ arm-none-eabi-gdb
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#. Connect to the board's serial console
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Usually you connect a USB-to-serial adapter to the board's serial console so you can see debug logging or
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execute Apache NuttX Shell (nsh) commands. You can access the serial console from Linux with the ``picocom`` terminal
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program. From another terminal, do this:
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.. code-block:: bash
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$ picocom -b 115200 /dev/ttyUSB0
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#. Set gdb to talk with the J-Link
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::
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(gdb) target extended-remote :2331
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#. Reset the board
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::
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(gdb) mon reset
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#. You may need to switch to the serial console to hit a key to stop the board from booting from its boot monitor
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(U-Boot, in the case of the SAMA5 boards from Microchip).
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#. Halt the board
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::
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(gdb) mon halt
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#. Load nuttx
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::
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(gdb) file nuttx
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(gdb) load nuttx
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`/home/adamf/src/nuttx-sama5d36-xplained/nuttx/nuttx' has changed; re-reading symbols.
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Loading section .text, size 0x9eae4 lma 0x20008000
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Loading section .ARM.exidx, size 0x8 lma 0x200a6ae4
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Loading section .data, size 0x125c lma 0x200a6aec
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Start address 0x20008040, load size 654664
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Transfer rate: 75 KB/sec, 15587 bytes/write.
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(gdb)
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#. Set a breakpoint
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::
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(gdb) breakpoint nsh_main
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#. Start nuttx
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::
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(gdb) continue
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Continuing.
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Breakpoint 1, nsh_main (argc=1, argv=0x200ddfac) at nsh_main.c:208
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208 sched_getparam(0, ¶m);
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(gdb) continue
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Continuing.
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Debugging Shortcuts
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-------------------
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Note that you can abbreviate ``gdb`` commands, ``info b`` is a shortcut for
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``information breakpoints``; ``c`` works the same as ``continue``, etc.
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----
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Next up is :ref:`configuring`.
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