When developing for microcontrollers and for example my leds aren't working, I like to define a place in memory where I write values to depending on the place in code. Then just read out that memory address with OpenOCD (jtag of swd).

  #define debugVar        ((uint32_t *) 0x10007000)
  *debugVar = 1;     
  *debugVar = 2;
  *debugVar = 0xdeadcafe;