Fast encoder sampling rate for nRF52xx

[Omri Friedman]

We need to sample two digital inputs GPIOs at rate of 100khz-1mhz. How can we do that? The QDEC is only good for up to 128us (~7khz) which is too slow for us. Is there a way to sample GPIO with DMA? If not, is there a way to do that without using interrupt every 10us?

[Sigurd]

Hi,

You should be able to do this using GPIOTE, PPI and a TIMER in counter mode. See this post for some more information.

[Omri Friedman]

Assuming i connect GPIOTE to a encoder digital input (0/1) and i manage to increment a timer per every rising or falling, can i then sample either the 0/1 value or the timer counter into a DMA? I must find a way to track the timing of the encoder changes. Example: read 0 after 100us, then read 1 after 25us, then read 0 after 75us, etc. I need to know to pattern timing in resolution of 10us

[Sigurd]

Hi,

In order to keep track of time, you will need to use an additional TIMER instance configured in timer mode. Use the TIMER TASKS_CAPTURE to capture the time when e.g. you get a COMPARE EVENT on the TIMER you use as counter.