DevGuide/GDB OpenOCD Debug

JTAG adapters

Recently some new JTAG adapters that use the FTDI2232 USB-parallel converter were introduced through OpenOCD (you can try your Wiggler with that, too). USB JTAG adapters include Floss-JTAG, Olimex or Amontec and also fine with Windows (Yagarto).

Also see DevGuide/OpenOCD for installation and configuration instructions.

Debugging with GDB over JTAG

Procedure

1. Start openocd in a new shell since this process needs to remain running.

   To connect to the Lisa/L board run the command

   openocd -f interface/lisa-l.cfg -f board/lisa-l.cfg

   To connect to the Lisa/M board via FLOSS-JTAG run the command:

   openocd -f interface/flossjtag.cfg -f board/lisa-l.cfg

1. Start GDB with an argument of the elf file created and uploaded to the board.

   If you programmed with the ap target then the command would be along the lines of

   /opt/paparazzi/arm-multilib/bin/arm-none-eabi-gdb var/<airframe>/ap/ap.elf

   Replace <airframe> with the name of the airframe that has been built.

2. Now connect GDB to the board

   target remote localhost:3333

3. Now we need to set some break points in the code.

   In this example the ap target was part of the rotorcraft and main.c contains the main program. Open rotorcraft sw/airborne/firmwares/rotorcraft/main.c and find a line at which you'd like to set a break point.

   break main.c:113

4. Stop the currently running code

   monitor reset halt

5. Reset the code back to the start

   monitor reset init

6. Now we can run the program which will stop at the break point we set.

   continue

Useful commands

• We probably want to ignore the interrupt calls for the moment so we can step through the code as it's being called. Note that we don't always want to do this. (STM32 command only)

  monitor cortex_m3 maskisr on

• A stack trace can be printed with the command

  bt

• show the variable of a variable

  print i2c1.status

• Show (eXamine) the value of the 9 bytes hardware register at address 0x40005800 and show them in hex format:

  x/9x 0x40005800

• In some cases you may not be able to access some memory areas in the mcu, in that case you should try:

  set mem inaccessible-by-default off