NRF_LOG printing old lines

[AmiguelS]

Hello!

When using the NRF_LOG module along with a JLink, when I connect the probe to the nRF the RTTClient prints out the first lines that were written when the probe was disconnected, instead of the most recent ones.

Imagine I disconnect the JLink probe from the nRF and reboot it. During startup some status messages are printed using NRF_LOG. After some time, an error occurs and to see what error it was I connect the nRF to the JLink, to get tjhe printed messages. What then shows up in the RTTClient are the first 13 lines of the initial status messages, while I expected it to be the most recent 13 lines, where the error code was available.

Is this behavior configurable?

I'm using SDK 12.3.

Thanks!

[Einar Thorsrud]

Hi,

Are you sure that you are only seeing the first messages? Could it be for example that the nRF has been reset when attaching the debugger, and that you see the messages logged after the reset? The RTT buffer is initialized by the firmware on the nRF after reset, so any earlier messages should not be shown on the RTT terminal.

[AmiguelS]

I can confirm the device has not been reset.

[Einar Thorsrud]

I see. Is NRF_LOG_ALLOW_OVERFLOW set in your projects sdk_config.h file?

[AmiguelS]

Hello. No, that flag is not available on the version of the SDK I am using (12.3). I will add this information to the original question.

[Einar Thorsrud]

Edit: deleted this content as the suggested solution was invalid.

[AmiguelS]

Wont this block the processor if the FIFO is full, as stated?

I was looking for deferred operation but with FIFO overwriting, instead of skipping the messages.

[Einar Thorsrud]

Yes, you are right, I was not thinking clearly. (Will update my previous post afterwards, as it was incorrect).

It does not seem like the SEGGER_RTT library support overwriting unread logs after all. It should be possible to update the library to do it (after all, all it really does is write data to a RAM buffer), but I do not immediately see how.