SAADC battery level on NRF52 custom board

RE: SAADC battery level on NRF52 custom board

bjorn-spockeli — Mon, 21 Nov 2016 12:10:04 GMT

Can't really see why you're seeing VDD divided by 2 when using the same code on a custom board. I guess these are obvious questions, but 1) have you verified that you see the correct voltage(VDD) on the VDD pins of the the nRF52 on your custom board? 2) Have you verified that you're not measuring on the wrong pin/channel?

RE: SAADC battery level on NRF52 custom board

piff — Wed, 16 Nov 2016 05:33:13 GMT

Not using any external component : I was assuming the NRF_SAADC_INPUT_VDD sample the VDD directly from power supply. The same apply to the Nrf52 DK

RE: SAADC battery level on NRF52 custom board

butch — Tue, 15 Nov 2016 22:53:51 GMT

OK, that makes sense. But both boards should still have a bypass capacitor on the network that includes the Vdd pin of the nRF and the battery. Is it the same size and type of capacitor? I don't really think that is the problem. BTW I think you should have commented on my comment instead of answering because now other readers will see the question has been answered and overlook your question.

RE: SAADC battery level on NRF52 custom board

butch — Tue, 15 Nov 2016 21:11:50 GMT

Using a capacitor? Several blogs/forum posts show resistor/divider nets along with a capacitor. What is the resistance of a battery? The sampled value depends on the resistance of the input. So you tested on the DK powered by the battery and not the USB? What differences in the schematics?