nRF52840 stops running after a while (>48 hrs) while powered by 2 AAA batteries

RE: nRF52840 stops running after a while (>48 hrs) while powered by 2 AAA batteries

catfish — Tue, 23 Mar 2021 15:37:40 GMT

i verified that my portable DMM is reading incorrectly while the batteries are in circuit. Not sure why, but the voltages are as expected when read with a benchtop HP DMM. So far the DUT has been functioning all day without a hangup so I'm not sure what caused the issues yesterday. Anyhow, seems to be working correctly so far. Thanks

RE: nRF52840 stops running after a while (>48 hrs) while powered by 2 AAA batteries

ketiljo — Tue, 23 Mar 2021 13:52:11 GMT

You should check the instrument against a known voltage source or another instrument. It's definitively not normal to measure this kind of voltages off a AAA cell.

RE: nRF52840 stops running after a while (>48 hrs) while powered by 2 AAA batteries

catfish — Tue, 23 Mar 2021 13:24:51 GMT

I know, the battery voltage is a bit of a surprise being that high. I normally do see new batteries exceed nominal (1.5) but not usually THAT high. When I started out it was even higher and I wondered if the DC-DC was influencing the value due to the low current draw. None of the LEDs are on and the batteries aren't draining much since they are still > than the expected 1.5V/cell. I restarted the code, with the same batteries, and it's running a day later so I'm not sure what could be causing a hangup but as of today it's running as expected. I'll keep testing and report back if there are any further issues. To note, I don't have the HW uart connected while running. The only connection to the dongle is the BLE connection.

As a side note, I'm really impressed with the API functionality provided. It's a steep learning curve but after getting through the basics the API is very thorough and a great guide (examples) to get started.

Thanks

RE: nRF52840 stops running after a while (>48 hrs) while powered by 2 AAA batteries

ketiljo — Tue, 23 Mar 2021 13:11:57 GMT

Are you sure about the nominal voltage of the batteries? 2xAAA shouldn't have more than 3.0 V

When you cut SB2 and connect SB1, you will operate the device in normal mode. So unless you have solder issues or do anything wrong with the code, I can't see why would drain the batteries this fast. Are any of the LEDs lit?