RE: Timer accuracy on NRF5340

Sigurd — Mon, 13 May 2024 20:02:38 GMT

Hi!

[quote userid="133615" url="~/f/nordic-q-a/111063/timer-accuracy-on-nrf5340"]I'm trying to sample few sensors at 2 kHz with a timer. Even though nrf5340 application core can run at 128 MHz, I couldn't achieve exact 500 us delay with timer.[/quote]

On the nRF53, you have 2 different timing peripherals. TIMER and RTC. TIMER uses the high-frequency clock source (HFCLK, 16 MHz), which means better resolution (62.5 ns). RTC uses the low-frequency clock source (LFCLK, 32 KHz), which means less resolution (~30 us).

The zephyr kernel timer, that is used when you are using e.g the function k_cycle_get_32, is using the RTC.

So in your code, you are using the TIMER, to generate a interrupt every 500us. But you are using the RTC to measure the accuracy of the TIMER. So you are in fact getting a accurate interrupt every 500us, but the method you are using to measure the accuracy is what's adding the inaccuracy in your measurements.

RE: Timer accuracy on NRF5340

Hakon — Fri, 10 May 2024 12:50:01 GMT

Hello,

most of the staff is away for vacation, so there will be some delays in response time. Thank you for your patience.

RE: Timer accuracy on NRF5340

sero — Thu, 09 May 2024 19:30:09 GMT

By the way, I'm using NRF Connect SDK v2.6.1.