What is the delay time from wfe to interrupt?

RE: What is the delay time from wfe to interrupt?

Dmitry — Sat, 16 Jan 2021 16:08:31 GMT

Ahh, I missed out that your interrupt already comes from timer... HFCLK is running.

Did you write your own low-level interrupt handler, or use app_timer handler? What is an interrupt delay if you remove WFE instruction?

For nRF52832, CPU wake-up time (T_IDLE2CPU)=3us. Other tickets (for example, this and this) have reported 10-12 us delay when running from flash and 3-4 us when running from RAM. Especially, look at the second link, an oscillogram for "running from RAM" case - the delay between hardware PPI-triggered event and interrupt handler is ~1.1us, so I don't think you can get much less.

RE: What is the delay time from wfe to interrupt?

Austin (S.F.) — Sat, 16 Jan 2021 12:15:15 GMT

Hi Dmitry

1. System already in HFCLK

2. Timer at 16MHz

Also, the question is why enter Timer interrupt so slow?

In my imagine, it should be less then 0.3us.

I need more time to execute more instructions in once interrupt.

Austin

RE: What is the delay time from wfe to interrupt?

Dmitry — Sat, 16 Jan 2021 09:15:18 GMT

Hi Austin,

the specification says that startup time for internal ocsillator is 3us, so 1.3us is quite a good result. To achieve faster response, you can try to force HFCLK to run continuously by keeping some peripheral running (for example, timer at 1MHz), but power consumption will increase significantly.