After running for a period of time (about 10 days), some devices do not work

[Victor A]

Some of the products we produce do not work after about 10 days.
Our firmware starts the watchdog module as soon as it starts, and sets the timeout period to 30s.
And read and write parameters stored in the flash.
After that, initialize the RC crystal, run the application, go to sleep mode, and wake up with app_timer

After testing, we found some specific phenomena:
1. The normal equipment can collect the pulse signal of the high frequency crystal oscillator when RC crystal oscillator is calibrated.
The abnormal device can not collect the high frequency crystal pulse signal
2. If a program problem causes a crash, the watchdog should restart after 30 seconds, and the working pulse signal of the high-frequency crystal oscillator when reading and writing the flash can be seen, but the abnormal device cannot collect it.This means the watchdog is not working.

We suspect that the program does not run because the RC crystal oscillator does not work. Would you like to know what causes the RC crystal oscillator to not work during the normal operation of the program

翻译

搜索

复制

翻译

搜索

复制

[Victor A]

I used NRF_CLOCK_LFCLKSRC_RC_250_PPM_TEMP_8000MS_CALIBRATION.

If the temperature remains unchanged and the RC oscillator is not calibrated for a long time, is there a risk that the RC oscillator will stop working

翻译

搜索

复制

[Priyanka]

Hi,

Victor A said:

If the temperature remains unchanged and the RC oscillator is not calibrated for a long time, is there a risk that the RC oscillator will stop working

It's not impossible, but not highly likely. But yes, if the temperature remains unchanged and the RC oscillator is not calibrated for a long time it can lead to a slight drift in the RC oscillator’s frequency, which can affect the accuracy and functionality and in turn cause issues in wake-up times and the watchdog. 

Maybe try increasing the calibration frequency to, say, every 2000ms? And also ensure that the LFCLK is properly initialised before you start the peripherals. Also, using an external crystal can provide more stability than the RC oscillator.

-Priyanka

[Victor A]

Priyanka said:

which can affect the accuracy and functionality and in turn cause issues in wake-up times and the watchdog. 

Does this mean that the RC oscillator stops working, or does the frequency drift?

翻译

搜索

复制