SAADC configuration

RE: SAADC configuration

JohnnyMcMan — Sat, 01 Jun 2019 22:20:40 GMT

Thank you awneli.

RE: SAADC configuration

awneil — Fri, 31 May 2019 08:47:39 GMT

[quote userid="7377" url="~/f/nordic-q-a/47962/saadc-configuration/190196"]you can also configure it to be VDD in case you want to measure the battery voltage[/quote]

For the avoidance of doubt, that will only work in cases where the battery is directly connected to VDD - not via a regulator!

JohnnyMcMan: The options for selecting inputs are illustrated in the Product Specification:

RE: SAADC configuration

Einar Thorsrud — Fri, 31 May 2019 08:33:51 GMT

Hi,

V(p) is by definition the voltage at the point you measure. That is normally the analog input pin, but you can also configure it to be VDD in case you want to measure the battery voltage. Referring to your code I see you configure the input pin like this:

  NRF_SAADC->CH[ANALOGNI_PIN].PSELP = SAADC_CH_PSELP_PSELP_VDD << SAADC_CH_PSELP_PSELP_Pos; //ocitavas vrednost ulaza na analognom pinu

This means that you do not hook any of the analog input pins to the SAADC, but instead, you connect the SAADC input to the VDD. So, in this case, VDD = V(p). If you want to measure an analog input pin, you have to specify that pin instead.

For instance, to measure the voltage on AIN0 (P0.02) you should set it to NRF_SAADC_INPUT_AIN0 (SAADC_CH_PSELP_PSELP_AnalogInput0) instead.