RE: Question about how to check the external resistance and output of lpco

Sigurd — Mon, 21 Aug 2023 15:44:16 GMT

Hi,

[quote user=""]Can lpcomp use a larger resistor than this?[/quote]

The main thing here is that voltage on the GPIO input should not be higher than VDD voltage. This is also true for LPCOMP. The post you linked to explained it like this. "We also want R2 to be large. R2 should be chosen such that the input voltage does not exceed Vdd when the battery is full (4.2 V). In this example Vdd is 3.3 V, so we choose R2 to be 2 MΩ which will give 3 V at AIN when battery is 4.2 V."

[quote user=""]So what I'm curious about, is reading the output of lpcomp. Can I use nrf_gpio_pin_read() as I read normal GPIO?[/quote]

No. Normally, you get an event when the input is below/above a threshold. But, you can also trigger a reading with the SAMPLE task, and read the result in the Compare result register. See https://infocenter.nordicsemi.com/topic/com.nordic.infocenter.nrf52832.ps.v1.1/lpcomp.html?cp=5_2_0_38#concept_tdv_zkx_lr on how it works.