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 think the best solution is to use a transistor as an amplifier for this signal, and then use a normal GPIO input.

Assuming you simply want to detect that there is a pulse, and you dont want to measure its length, you can feed the signal via a capacitor to a forward biased transistor

Note. This will take some current all the time, but you can probably limit this by careful choice of bias resistor values, and perhaps use a FET rather than a bipolar transistor.

Edit. Note. This method would also have a small delay between the pulse arriving, and it being transferred though the capacitor.

[Roger Clark]

@kernels

No worries..