RTT Logging is causing lags and WDT Resets

RE: RTT Logging is causing lags and WDT Resets

Vidar Berg — Thu, 29 Apr 2021 12:43:37 GMT

Thanks for the update. Yes, the behavior makes sense if you are encountering this bug. We are planning to fix it!

RE: RTT Logging is causing lags and WDT Resets

Dave_couling — Tue, 27 Apr 2021 17:43:27 GMT

Looks like a similar error to this: https://devzone.nordicsemi.com/f/nordic-q-a/63998/freertos-wdt-sdk17-problem

Is there a plan to fix this issue in a new SDK?

I removed the following line in nrf_drv_clock_init() from nrf_drv_clock.c which seems to fix the issue.

// if (nrf_wdt_started())
// {
// m_clock_cb.lfclk_on = true;
// }

RE: RTT Logging is causing lags and WDT Resets

Dave_couling — Tue, 27 Apr 2021 17:16:37 GMT

I've traced this down to a vTaskDelay which is not returning the first time you run the code after programming. If I reset the the chip on the IDE and run again everything it fine. I was using SDK 17.0.2. I reverted back to SDK 16.0 which I've test before and everything works fine. So this seems to be related to SDK 17.0.2 and its freeRTOS library

RE: RTT Logging is causing lags and WDT Resets

Dave_couling — Tue, 27 Apr 2021 16:05:39 GMT

1. Yes it still hangs

2. Yes same behavior with the UART backend

3. Using Putty

RE: RTT Logging is causing lags and WDT Resets

Vidar Berg — Tue, 27 Apr 2021 08:56:09 GMT

Thanks for confirming. I have a few more follow up questions if you don't mind:

1. Have you tried to extend the WD timeout to more than a few seconds to see if the program only hangs temporarily?

2. Do you get the same behavior if you select the UART backend?

3. How are you viewing the RTT logs, in SES or RTTViewer?

RE: RTT Logging is causing lags and WDT Resets

Dave_couling — Tue, 27 Apr 2021 07:51:42 GMT

I've made sure that I'm not using Blocking mode in my sdk_config.h. But still the WDT module won't feed. I've tried placing the WDT feed in a task with a higher priorty than the Logging thread, but its still getting blocked. Which means its happening in the backend module somehow.

Oddly its only an issue after each programming, but if I restart the debug from the IDE is runs fine. Could it be a JLink driver issue?

RE: RTT Logging is causing lags and WDT Resets

Vidar Berg — Tue, 27 Apr 2021 06:52:55 GMT

Hello,

The RTT backend shouldn't become blocking unless you have selected the 'BLOCK' mode in your configuration settings:

Could you please check that you don't have this mode selected? I can't think of any other obvious reasons for why logging is preventing the WDT from being fed.