How do I make certain that all NRF_LOG messages makes it to RTT viewer?

[ccasebeer]

Sometimes, the output of the NRF_LOG commands does not make it to the RTT viewer.

The output of such commands as NRF_LOG_INFO() and NRF_LOG_DEBUG() and NRF_LOG_HEXDUMP_DEBUG()

are cut short on the RTT viewer and are not complete. Sometimes, for example upon a fresh connection of RTT Viewer, full messages will be seen and then as the program runs, those same outputs which were complete become no longer complete as viewed on the J-Link RTT Viewer.

How can I setup my system to **guarantee** that all NRF_LOG() commands get to the RTT viewer.

I am using NRF5 SDK 17.02. I use the J-Link RTT Viewer V6.88a. I am attached to an NRF52840 DK board over USB.

Another related debug question I have is:

Is there a way to command line view the RTT output and integrate it more tightly with command line building as done with MAKE and VSCODE? My current pathway is issuing a "make flash" and then going to my RTT Viewr GUI.....and hitting the connect/disconnection File option until I start seeing debug messages, most likely missing plenty of debug.

Is there a way to ensure that after building and flashing, that an RTT viewer logger is spawned and captures all debug output as the device boots?

The RTT viewer is a great tool, but our team has had trouble with missing debug messages for the entirety of development. I'd like to fix this once and for all.

I know there are a multitude of NRF_LOG settings in the SDK_CONFIG.H. We still haven't found the magic combination.

NRF_LOG_DEFERRED 0 has fixed other problems, including printing old data but not the problem of missing debug data.

Kind Regards,
Chris

[ovrebekk]

Hi Chris

Do you ever get messages about dropped logs?

Is there a lot of log activity happening when this issue occurs, meaning you might be pushing the log throughput to its limits, or do you see log data missing even when there is not a lot of activity?

Best regards
Torbjørn

[ccasebeer]

Thanks for the help. I appreciate it.

I would say, yes, when alot is being printed, close together, I am more likely to see things lost.

Is there a throughput limit on RTT? Can any sdk_config.h settings help me?

Right now I believe we can spare memory/latency on the system, especially on a debug system.

Thank You,

Chris

[ovrebekk]

Hi Chris

I don't know the exact throughput limit when using RTT, but increasing the SWD frequency when you enable the RTT Client should provide more throughput. Could you give this a try?

Increasing the NRF_LOG_BACKEND_RTT_TEMP_BUFFER_SIZE parameter in sdk_config.h could also help when you have a lot of logging activity, at least if you have very long log messages. 

Best regards
Torbjørn