Is that bad to call RTT functions if there is no SEGGER connected?

[Sébastien Despont]

Is that bad to call RTT functions if there is no SEGGER connected?

I mean, if there is no RTT viewer connected, what the RTT library does with the message to transmit? Does it put the message in queue? Does it use some RAM? If I forgot to remove this RTT calls in production mode, is that possible that my application crash due to RTT calls?

Here is an example of RTT function I call every seconds for debug purpose :

SEGGER_RTT_SetTerminal(terminal);
SEGGER_RTT_printf(0,"%s %d\n",prefix,number);

[Bill Siever]

The RTT web page says:

The developer does not have to create a special debug version and the code can stay in place in a release application.

Since the RTT routines just copy to a special block in memory they can run without the debugger connected. The final application would have slightly worse performance if it's present (a little slower; more code executed so more power consumption; RAM allocated that isn't needed).

Just to add a little more to Martijn's response: It uses non-blocking by default. The Q&A section on the RTT page (https://www.segger.com/jlink-rtt.html) mentions:

SEGGER-RTT uses non-blocking mode per default, which means it does not halt program execution if no debugger is present and J-Link is not even connected. The application program will continue to work

[Sébastien Despont]

Thanks for your answer, can you link the RTT web page?