Using GDB stub

• Add #include <GDBStub.h> to the sketch

• Upload the sketch

• Redirect serial port to TCP port:

  tcp_serial_redirect.py -p /dev/tty.SLAB_USBtoUART -b 115200 --spy -P 9980 --rts=0 --dtr=0
  

  Change port and baud rate as necessary. This command requires python and pyserial.

• Observe serial output:

  nc localhost 9980
  

• Once crash happens, close nc and start gdb:

  xtensa-lx106-elf-gdb /path/to/Sketch.cpp.elf -ex "target remote :9980"
  

  Or, using the provided gdbcmds file:

  xtensa-lx106-elf-gdb /path/to/Sketch.cpp.elf -x gdbcmds
  

• Use gdb to inspect program state at the point of an exception.

Tips and tricks

• Upon including GDBStub.h in the sketch, the target is automatically halted when software WDT fires, with

  *((int*)0) = 0;
  

  at the top of __wrap_system_restart_local in core_esp8266_postmortem.c.

License

Espressif MIT License. See License file.