AIN0 not measuring on pca10028

RE: AIN0 not measuring on pca10028

gaminn — Thu, 07 Jan 2016 15:16:52 GMT

Classic example of RTFM :) Thanks.

RE: AIN0 not measuring on pca10028

Stefan Birnir Sverrisson — Thu, 07 Jan 2016 13:11:58 GMT

Hi gaminn

To disconnect the crystal and enable the pins as GPIO/AIN pin you need to perform the steps described in the nRF51 DK User guide, section 5.6

RE: AIN0 not measuring on pca10028

gaminn — Thu, 07 Jan 2016 05:24:27 GMT

I init my ADC for 10 bit, 1/3 divider and VDD/2 reference.

RE: AIN0 not measuring on pca10028

gaminn — Thu, 07 Jan 2016 05:22:06 GMT

Please correct me, but in school, they told us, that for DC crystal acts as infinite resistance, so it won't influence slowly changing ADC signal. Also my multimeter shows me correct voltage on AIN0 and AIN1. But ADC won't measure it.

RE: AIN0 not measuring on pca10028

RK — Thu, 07 Jan 2016 01:10:21 GMT

Just because the nrf51 isn't using the crystal itself doesn't mean it disappears from the universe, or from the circuit. So unless you've physically removed it from the board you are shorting your AIN0/AIN1 voltage across a crystal, which depending on frequency of your input is acting anything from a small resistance to a large one. So it's probably not going to work.

RE: AIN0 not measuring on pca10028

xtting — Thu, 07 Jan 2016 00:47:21 GMT

I believe you should attach all of your config code.