LPCOMP issue with sensing multiple inputs

RE: LPCOMP issue with sensing multiple inputs

lance338 — Tue, 21 May 2019 12:54:26 GMT

The delay works. Thank you for the suggestion Kenneth

RE: LPCOMP issue with sensing multiple inputs

Kenneth — Tue, 21 May 2019 07:16:37 GMT

I would have tried with a delay (e.g. 50us) or power cycle the LPCOMP when it's disabled like this:

*(volatile uint32_t *)0x40013FFC = 0;
*(volatile uint32_t *)0x40013FFC;
*(volatile uint32_t *)0x40013FFC = 1;

RE: LPCOMP issue with sensing multiple inputs

lance338 — Tue, 21 May 2019 02:21:58 GMT

We don't need very accurate. Just simply a detection of voltage crossing below/above a level. The ADC has it own challenge in our application. Is there any thing you can think of to get the LPCOMP to work on multiple inputs?

RE: LPCOMP issue with sensing multiple inputs

Kenneth — Mon, 20 May 2019 14:26:32 GMT

The LPCOMP is intended to be used for a low power wakeup from sleep when an input drop a specified level, it is not very accurate either. So the way you use it is not as intended, instead the SAADC is better since it will provide a much better reading of the individual pins.

RE: LPCOMP issue with sensing multiple inputs

lance338 — Mon, 20 May 2019 14:02:52 GMT

Thanks Kenneth. Tried clearing Event_ready and it doesn't work. Do I have to wait between enables?

Also, can you share why the ADC is better for multiple inputs?

RE: LPCOMP issue with sensing multiple inputs

Kenneth — Mon, 20 May 2019 12:13:17 GMT

Have you considered using the SAADC instead? Should be a better solution to read multiple pins.

In you case maybe you should also clear NRF_LPCOMP->EVENTS_READY = 0 between "reads".