RE: Constant Delay of a SAADC channel

ovrebekk — Thu, 10 Jun 2021 09:38:34 GMT

Hi Michael

It's a bit hard to say what is happening here. My initial thought was that the buffer setup was incorrect and that the ADC would write to the buffer one position off, so that an old sample is left for one of the channels, but just by looking at your code I can't spot any errors.

If I understand your code correctly you will get interrupts from the ADC driver every 1ms, which could be problematic if there are a lot of other interrupts in the system, but if this was the case I would expect to see more drastic errors than the one you are seeing. In general I would recommend increasing the size of the buffers in order to reduce the CPU overhead, as long as you can accept a bit higher latency.

Have you tried disabling the handover of ADC data to the UART and the NUS service to see if the problem still remains?
You should be able to check the values using the debugger in the case where you don't send the ADC data anywhere.

Best regards
Torbjørn