SEGGER_RTT_MODE_BLOCK_IF_FIFO_FULL when no probe

[Fabien Comte]

Hello,

I use a debugger probe (Segger Jlink) with the sdk_config.h setting SEGGER_RTT_MODE_BLOCK_IF_FIFO_FULL.

When my probe is not connected, there my product is blocked => i guess that a probe detection is missing in SEGGER_RTT.c, right ?

Where can I fix it please ?

Thank you

[RK]

well it's not missing, Segger didn't put it in and treats SEGGER_RTT_MODE_BLOCK_IF_FIFO_FULL to mean it'll block if the FIFO is full whether or not you have a probe connected. That' the semantic of that flag. 

If you don't want that, don't use that flag, or do a probe check yourself when you configure the buffer and choose the flag depending on whether you have a probe. 

[Fabien Comte]

Ok thank you for your help.

[Gein]

How does one perform a probe check in s/w?

Here's a solution... set it to the default non-blocking mode, and only after receiving a keypress decide that there is a connection.  I added this API to SEGGER_RTT.c:

void SEGGER_RTT_Flags(unsigned up_flags, unsigned down_flags, unsigned *up_flags_old, unsigned *down_flags_old) {
  SEGGER_RTT_CB* p;
  p = &_SEGGER_RTT;

  if (up_flags_old) {
	  *up_flags_old = p->aUp[0].Flags;
  }
  if (down_flags_old) {
	  *down_flags_old = p->aDown[0].Flags;
  }
  if (up_flags != (unsigned)-1) {
	  p->aUp[0].Flags    = up_flags;
  }
  if (down_flags != (unsigned)-1) {
	  p->aDown[0].Flags  = up_flags;
  }
}

[Fabien Comte]

I use that (DHCSR is compatible with Cortex M4 only => nRF52840 only)

int SEGGER_RTT_TerminalOut (char TerminalId, const char* s) {
  int                   Status;
  unsigned              FragLen;
  unsigned              Avail;
  SEGGER_RTT_BUFFER_UP* pRing;
  
	// C_DEBUGEN == 1 -> Debugger Connected
	if (CoreDebug->DHCSR & CoreDebug_DHCSR_C_DEBUGEN_Msk)
	{

	}
	else
	{
		return STRLEN(s);
	}
	
	//
    INIT();

and I modified nrf_log_internal.h like this

#define NRF_LOG_INTERNAL_INST(level, level_id, p_inst, ...)                              \
    if (NRF_LOG_ENABLED && (NRF_LOG_LEVEL >= level) &&                                   \
        (level <= NRF_LOG_DEFAULT_LEVEL) && (CoreDebug->DHCSR & CoreDebug_DHCSR_C_DEBUGEN_Msk))                                                \
    {                                                                                    \
        if (NRF_LOG_INST_FILTER(p_inst) >= level)                                        \
        {                                                                                \
            LOG_INTERNAL(LOG_SEVERITY_INST_ID(level_id, p_inst), __VA_ARGS__);           \
        }                                                                                \
    }

#define NRF_LOG_INTERNAL_MODULE(level, level_id, ...)                                    \
    if (NRF_LOG_ENABLED && (NRF_LOG_LEVEL >= level) &&                                   \
        (level <= NRF_LOG_DEFAULT_LEVEL) && (CoreDebug->DHCSR & CoreDebug_DHCSR_C_DEBUGEN_Msk))                                                \
    {                                                                                    \
        if (NRF_LOG_FILTER >= level)                                                     \
        {                                                                                \
            LOG_INTERNAL(LOG_SEVERITY_MOD_ID(level_id), __VA_ARGS__);                    \
        }                                                                                \
    }

#define NRF_LOG_INTERNAL_HEXDUMP_INST(level, level_id, p_inst, p_data, len)        \
    if (NRF_LOG_ENABLED && (NRF_LOG_LEVEL >= level) &&                             \
        (level <= NRF_LOG_DEFAULT_LEVEL) && (CoreDebug->DHCSR & CoreDebug_DHCSR_C_DEBUGEN_Msk))                                          \
    {                                                                              \
        if (NRF_LOG_INST_FILTER(p_inst) >= level)                                  \
        {                                                                          \
            LOG_HEXDUMP(LOG_SEVERITY_INST_ID(level_id, p_inst),                    \
                                     (p_data), (len));                             \
        }                                                                          \
    }

#define NRF_LOG_INTERNAL_HEXDUMP_MODULE(level, level_id, p_data, len)              \
    if (NRF_LOG_ENABLED && (NRF_LOG_LEVEL >= level) &&                             \
        (level <= NRF_LOG_DEFAULT_LEVEL) && (CoreDebug->DHCSR & CoreDebug_DHCSR_C_DEBUGEN_Msk))                                          \
    {                                                                              \
        if (NRF_LOG_FILTER >= level)                                               \
        {                                                                          \
            LOG_HEXDUMP(LOG_SEVERITY_MOD_ID(level_id),                             \
                                     (p_data), (len));                             \
        }                                                                          \
    }