App Timer not producing interrupts for ~1Sec

RE: App Timer not producing interrupts for ~1Sec

Eric — Mon, 28 Nov 2022 18:16:51 GMT

I wanted to follow up on this for anyone else that is running into an issue. I solved the issue by switching to a hardware timer rather than using app_timer. My suspicion is that my timer internals where very short and very frequent (<1mS period). The overhead of the app_timer module doesn't seem to be well suited for this.

After switching to a hardware timer I have not seen any issues.

RE: App Timer not producing interrupts for ~1Sec

Jared — Tue, 22 Mar 2022 13:15:25 GMT

Hi there,

I have some more question regarding your application:

Are you in a BLE connection or advertising while this is happening?
Does your application do any writes to flash memory?
What priority are you running the module at?
Could you try to simplify what modules that is used in your program and see if the issue still happens? For example, what happens if you comment out the Softdevice and SPI code. Is the app timer still not triggering correctly? What if you just include the SPI code?

regards

Jared

RE: App Timer not producing interrupts for ~1Sec

Eric — Mon, 21 Mar 2022 20:35:52 GMT

I do have a 32K LFXO crystal on the board and the SDK is configured to use it. Here is a snippet from the SDK_config

// <e> NRFX_CLOCK_ENABLED - nrfx_clock - CLOCK peripheral driver
//==========================================================
#ifndef NRFX_CLOCK_ENABLED
#define NRFX_CLOCK_ENABLED 1
#endif
// <o> NRFX_CLOCK_CONFIG_LF_SRC  - LF Clock Source
 
// <0=> RC 
// <1=> XTAL 
// <2=> Synth 
// <131073=> External Low Swing 
// <196609=> External Full Swing 

#ifndef NRFX_CLOCK_CONFIG_LF_SRC
#define NRFX_CLOCK_CONFIG_LF_SRC 1

Also as an additional debugging step I changed the spi timers over from the app_timer module to the nrfx_timer module. This issue is not exhibited at all when using the timer module. Although this allows me to move forward I still want to root cause the issue I'm seeing with app_timer because even if I keep the nrfx_timer implementation for the SPI I still want to use the app_timer for other parts of the code.

RE: App Timer not producing interrupts for ~1Sec

Jared — Mon, 21 Mar 2022 11:44:33 GMT

Hi there!

Thank your for a great description of your issue, and what debug steps you have already tried.

Do you have a LFXO crystal on your board or are you using the internal RC oscillator for the LFCLK?

regards

Jared