nrf52 Battery Measurements

RE: nrf52 Battery Measurements

Kenneth — Wed, 19 Sep 2018 12:19:02 GMT

I assume the battery is below 3.6V at all times. In that case you don't need a resistor bridge. Internally there is already a 1/6 divider and a 0.6V reference. So this means that if you measure 3V battery, the measurement will be 3V/6 = 0.5V. If you have 8bit resolution, then you will measure approx 2^8 * (0.5V/0.6V) = 213 decimal @ 8bit resolution (or 2^10 * (0.5V/0.6V) = 853 decimal @ 10bit) when VDD= 3V.

RE: nrf52 Battery Measurements

Bilal — Wed, 19 Sep 2018 11:39:28 GMT

Hello Kenneth,

Does it only depends on input voltage ? because most of the example I see has voltage dividers as well. In my setup, chip is directly connected to battery. Thanks

RE: nrf52 Battery Measurements

Kenneth — Wed, 19 Sep 2018 11:30:34 GMT

That should simply be opening \examples\peripheral\saadc from a recent nRF5 SDK and change to in saadc_init():

nrf_saadc_channel_config_t channel_config = NRF_DRV_SAADC_DEFAULT_CHANNEL_CONFIG_SE(NRF_SAADC_INPUT_VDD);