nRF52840 input circuit question

[Oleg]

Dear Engineers! have a questions about the Input circuit of nRF52.

I have to monitor the signal LEVEL from some sensor. The signal can be Positive or Negative current, so , the input of nRF52 should be internally pulled to (+) or (-) use int. resistors of typ. 13k according to the GPIO spec.

May questions:

1. is it possible to use GPIO UP/DN resistors in case of COMP (comporator) module ? or these GPIO resistors auto disconnected ?
2. is it possible to use SAADC Rladder PU/PD Resistors (160k) of RESP (+) if I will use SAADC at the same time with the COMP module ?
3. the COMP module has internal programmable Current ISOURCE of 2,5uA / 5uA and 10uA, so what happined in case of using SAADC and COMP at the same time ? ISOURCE current has negative direction ?

thank you!

[bjorn-spockeli]

Hi Oleg,

Q1: I do not think it is possible to enable the pull-up/down resistor when using aGPIO pin as an analog pin.

Q2: Yes, I do not think that should be an issue, see section 36.1 Shared Resources in the nRF52840 OPS

The ADC can coexist with COMP, LPCOMP and other peripherals using one of AIN0-AIN7, provided theseare assigned to different pins.

Q3: The ISOURCE programmable current has been removed from the nRF52840 due to Errata [84] COMP: ISOURCE not functional on the nRF52832.