Is there a way to detect 1ms pulse with voltage of around 300mV?

[KS]

We are already using ADC for battery sense, also tried using ADC and LPCOM but could not get any reliable result.

[Roger Clark]

I'm not sure which response you replied to, as you posted your response and an answer

Using the ADC is not ideal for pulse detection, because of the acquisition time

I don't know the acquisition time of the ADC on the nRF51822 but I'm fairly sure if you ran it constantly, you would be able to detect a 1mS wide pulse.

However normally pulse detection is done using GPIO and possibly via interrupt GPIOTE

Do you require a low power solution, as I don't think an OpAmp is likely to be low power.

What OpAmp did you try using, is it "rail to rail" i.e will it drive the output to the supply voltage ?

[Roger Clark]

@kernels

No worries..

[ovrebekk]

Hi

I see you already got a lot of good suggestions, but I would like to know what reference you used for the LPCOMP when you tried it?

Probably none of the internal references will cut is, as they could all be above 300mV (depending on your supply voltage).

You can still use an external reference though. You could set up a voltage divider to generate any voltage between 0 and VDD, and use that as reference on either the AREF0 or AREF1 pins.

I haven't tested this myself, but in theory it should allow you to wake up on the 300mV pulse.

You will have to disable the LPCOMP whenever you use the ADC though, which could be a problem depending on how often you get pulses and how critical it is that you detect them all.

Best regards
Torbjørn