Creating a load on a battery using the radio

[JZone]

I am in a need to measure a battery level under a constant load. Rather than adding a custom electronics, I am considering using the radio. I believe there is a way of doing that (see https://docs.nordicsemi.com/bundle/ncs-latest/page/nrf/samples/peripheral/radio_test/README.html).

For my use case I need something very simple, that could be embedded in our standard, production software. Would you please advise on the right register configuration ?

nRF52833

SDK 17

[hmolesworth]

Continuous Rx until advertising packet received (then restart Rx) with HFCLK crystal enabled I see 8.8mA @3V on nRF52832 with no DC-DC, no hardware attached to io pins and no peripherals enabled.

[JZone]

Thanks for the suggestions. The following solution seems to work

NRF_RADIO->MODE = 0; // 1 Mbps Nordic proprietary radio mode
NRF_RADIO->TXPOWER = 0x08; // +8dBm
NRF_RADIO->TASKS_TXEN = 1;

test_battery();

NRF_RADIO->TXPOWER = 0; // Set back to default

NRF_RADIO->TASKS_DISABLE = 1;

[hmolesworth]

Excellent suggestion. There is no +8dBm option on the nrf52832 (which I ran this test on) and I see these results @3V on nRF52832 with cpu awake, no DC-DC, no hardware attached to io pins and no peripherals enabled.

23mA at +4dBm is most useful for a faster battery test.

  NRF_RADIO->TXPOWER = 0x08; // +8dBm 11.35mA
  NRF_RADIO->TXPOWER = 0x04; // +4dBm 23.17mA
  NRF_RADIO->TXPOWER = 0x00; //  0dBm 17.42mA