nrf_drv_saadc_abort doesn't raise SAADC DONE task

RE: nrf_drv_saadc_abort doesn't raise SAADC DONE task

Jared — Tue, 25 Jun 2024 11:54:43 GMT

Hi there,

I totally forgot that you had already shared the code. I see that you start the abort task periodically by using the app timer, can you try to shorten the app timer interval to for example 900 or extend it to 3700 and see if it results in any difference on the number of samples reported when abort is called?

regards
Jared

RE: nrf_drv_saadc_abort doesn't raise SAADC DONE task

LimeSlice — Wed, 19 Jun 2024 13:49:43 GMT

See post’s original attachment

RE: nrf_drv_saadc_abort doesn't raise SAADC DONE task

Jared — Wed, 19 Jun 2024 12:51:10 GMT

Hi,

How are you aborting the sampling, how is it triggered, can you show me the code? I'm not 100% sure, but I would expect it to report the exact number of samples in that interval even though it didn't manage to sample all enabled channels,

regards

Jared

RE: nrf_drv_saadc_abort doesn't raise SAADC DONE task

LimeSlice — Tue, 18 Jun 2024 14:53:47 GMT

This is true that this works to get the last frame's number of samples. However, my 512 measurements are occurring from my SAADC being connected to a timer through the PPI to measure at a specific frequency. With this, each measurement is triggering a START then STOP event in the SAADC. Consequently, when I call nrf_saadc_amount_get() to read the RESULT.AMOUNT register, I am only receiving a value from the last measurement interval. For example, I have 3 SAADC channels, so whenever I read RESULT.AMOUNT, my value is either 3 or occasionally 6.

RE: nrf_drv_saadc_abort doesn't raise SAADC DONE task

Jared — Tue, 18 Jun 2024 13:15:42 GMT

Hi,

When you call nrfx_saadc_abort() it will effectively call trigger the NRF_SAADC_TASK_STOP task which will eventually result in the EVENTS_STOPPED to be generated. When that event has been generated, you can check the RESULT.AMOUNT register to see how many samples that has been transferred to RAM.

regards

Jared

RE: nrf_drv_saadc_abort doesn't raise SAADC DONE task

LimeSlice — Mon, 17 Jun 2024 13:53:40 GMT

Thanks Jared for the info!

I need to be able to cause an early stop using while still knowing how many samples were taken during the period before nrfx_saadc_abort was called. For example, my sampling period fills a buffer of 512 ADC measurements. If the abort is called and only 300 measurements were taken, I need to know this number and be able to still convert the 300 measurements with nrfx_saadc_buffer_convert. Do you have a suggestion on how I would accomplish this if nrfx_saadc_abort does not propogate the HW event to the application?

RE: nrf_drv_saadc_abort doesn't raise SAADC DONE task

Jared — Mon, 17 Jun 2024 11:48:57 GMT

Hi,

I'm guessing that your basing your assumption on this comment regarding the driver function:

NRFX_SAADC_EVT_DONE is a HW event that isn't propagated to the application in this case. Calling nrfx_saadc_abort() will trigger the task NRF_SAADC_TASK_STOP which again will generate the NRF_SAADC_EVENT_STOPPED.

regards

Jared

RE: nrf_drv_saadc_abort doesn't raise SAADC DONE task

LimeSlice — Fri, 14 Jun 2024 16:40:54 GMT

A little more info: I do observe the SAADC stop sampling, but I am not receiving a NRF_DRV_SAADC_EVT_DONE SAADC event in my saadc_callback handler as I would expect.