JLink RTT logs not flushing at device startup

RE: JLink RTT logs not flushing at device startup

AndoniV — Wed, 03 Jul 2019 14:24:01 GMT

Thank you Jørgen this really helped, sorry for the late reply!

RE: JLink RTT logs not flushing at device startup

Jørgen Holmefjord — Wed, 19 Jun 2019 13:45:26 GMT

I would recommend that you have a look at the RTT description on Seggers webpage.

The configs are used in SEGGER_RTT_Conf.h, and functions from SEGGER_RTT.h/c is used in NRF_LOG RTT backend to push the logs to the RTT terminal.

RE: JLink RTT logs not flushing at device startup

AndoniV — Wed, 19 Jun 2019 07:48:47 GMT

Hi Jørgen,

Sorry I did not provide the full context.

- I am using 15.2.0 but I've seen the same behaviour with 11.0
- I've used a J-Link base and a J-Link pro, both seem to be the same, I haven't tried using UART backend.
- I have tried disabling NRF_LOG_ALLOW_OVERFLOW with no difference.
- SEGGER_RTT_CONFIG_BUFFER_SIZE_UP is currently set to 512

Looking at the SEGGER RTT options, I changed the SEGGER_RTT_CONFIG_DEFAULT_MODE to 2 and now logs are flushed as they should, thank you for pointing me in the right direction.

Could I ask what are the effects of increasing the SEGGER_RTT_CONFIG_BUFFER_SIZE_UP and SEGGER_RTT_CONFIG_BUFFER_SIZE_DOWN? How do these play along with the NRF_LOG_BACKEND_RTT_xxx options and the NRF_LOG_xxx options?

Thank you very much,

Andoni

RE: JLink RTT logs not flushing at device startup

Jørgen Holmefjord — Thu, 13 Jun 2019 15:15:56 GMT

Hi,

Which SDK version are you using?

Are you only seeing this issue with this specific J-Link type, or it is general RTT issue? Have you tested to see if your get the same issue with UART backend?

Any change if you set NRF_LOG_ALLOW_OVERFLOW to 0? What is the size of SEGGER_RTT_CONFIG_BUFFER_SIZE_UP in your application?

Best regards,
Jørgen