CC2640R2F: Retaining variables during reset

lakshmikanth satyavolu

Part Number: CC2640R2F

Tool/software:

Hi Community,

My firmware hangs and stop advertising at very rare occasions which I cannot reproduce easily on my debugging. As a fix I would like to implement a watchdog timer to get the processor back alive.

But, few variables I required to continue flow of my code are resetting during wdt reset. I cannot write them into NVM memories present in my system as those will be updated every second. So, the erase cycles of NVM will be very frequent.

Is there any way I can retain few variables in RAM which are not going to be erased during resets?

Please suggest something.

Best

Lakshmi

over 1 year ago

0 Ryan Brown1 over 1 year ago

TI__Guru**** 217467 points

Hi Lakshmi,

There are some indications that you can store some variables in RAM which are not erased during a reset as demonstrated through specific OAD examples:

https://e2e.ti.com/f/1/t/892935
https://e2e.ti.com/f/1/t/967477
https://e2e.ti.com/f/1/t/1226161

As this cannot be fully relied upon, my suggestion is to configure the Watchdog TI Driver so that you may store values into NV memory before the Watchdog reset, as compared to updating NV memory values constantly. Please see further details from the CC26XX specific implementation and watchdog example.

Regards,
Ryan

0 lakshmikanth satyavolu over 1 year ago in reply to Ryan Brown1

Expert 1680 points

Hi Ryan,

>>> my suggestion is to configure the Watchdog TI Driver so that you may store values into NV memory before the Watchdog reset.

Initially I thought about this. But for some reason my wachdog callback is not getting invoked during hang. What could be the problem?

Best

Lakshmi

0 Ryan Brown1 over 1 year ago in reply to lakshmikanth satyavolu

TI__Guru**** 217467 points

Are you sure that the Watchdog is causing the device reset (SysCtrlResetSourceGet)? Is there already a HW assert that could block the Watchdog callback from being entered? And how are you configuring the Watchdog TI Driver? I suggest you consult the Debugging Guide.

Regards,
Ryan

0 lakshmikanth satyavolu over 1 year ago in reply to Ryan Brown1

Expert 1680 points

I created an event which will execute while() infinite loop which leads to watchdog timeout without reload. I am sure reset is caused by watchdog timeout. I am glowing an LED in wdt callback which is not happening.

Also, when I attached debugger and trying to hit the breakpoint in callback, when reset happens, jtag is disconnected from the target. How to hit the breakpoint before wdt reset happens?

Best

Lakshmi

0 Ryan Brown1 over 1 year ago in reply to lakshmikanth satyavolu

TI__Guru**** 217467 points

Please try to further evaluate and get familiar with the watchdog example callback mechanism and then implement a similar version into your application code while further debugging inside of your IDE.

Regards,
Ryan

Bluetooth®︎

Bluetooth forum

CC2640R2F: Retaining variables during reset