RE: Race condition with ADC driver

Malcolm — Mon, 20 Apr 2020 12:03:49 GMT

Thank you for your response.

I actually set up 3 separate channels to be sampled, and then I must process this data before sampling the same 3 channels again. I had a problem with Calibrate which was creating bogus samples, but this is fixed using the workaround in the errata sheet.

The way the device works is to perform one sample on each channel and then give an interrupt. This is fine for my application, except the Calibrate was messing up the buffer and I went to one sample and tried to change the channel, which was the problem I reported her.

Now I have fixed Calibrate, and realised I can use 3us and my application is acceptable.

I could interleave sampling with double buffering but there is a feature in the SAADC driver that set SAADC status to idle after checking a STOP condition, which is required as the workaround for calibrate.

As the application now works reasonably well, I am happy to leave as is.

Malcolm

RE: Race condition with ADC driver

haakonsh — Mon, 20 Apr 2020 11:23:18 GMT

There are two issues here:

You say you want the maximum sample rate, but you use a buffer that only holds a single sample for each adc channel, you need to increase to a more suitable number, otherwise, you will have a massive CPU overhead between each sample.
Why do you not use a TIMER and PPI to control the sample rate instead of triggering each sample manually via the CPU?

Do you mind sharing more information on what you want to achieve with the adc?