SAADC read on VDD giving a dip in value every 1 to 1.5 hours for approx 2 mins

RE: SAADC read on VDD giving a dip in value every 1 to 1.5 hours for approx 2 mins

Ameer Usman — Mon, 06 Jan 2020 08:03:23 GMT

Great, Thank you :)

RE: SAADC read on VDD giving a dip in value every 1 to 1.5 hours for approx 2 mins

Otso Jousimaa — Sun, 05 Jan 2020 09:58:20 GMT

Measuring on radio activity disable is how we do it at Ruuvi. Below is the screen capture of sampling (GPIO, blue) and battery voltage (VDD, red). I can't say for sure if it will fix your issue, but it has been very reliable for us on CR2477 batteries.

RE: SAADC read on VDD giving a dip in value every 1 to 1.5 hours for approx 2 mins

Ameer Usman — Sun, 05 Jan 2020 06:51:01 GMT

So so I am sampling on radio activity enable:

rc = radio_notification_init(3, NRF_RADIO_NOTIFICATION_TYPE_INT_ON_ACTIVE , NRF_RADIO_NOTIFICATION_DISTANCE_800US); //Changed from Active to Inactive to combat Voltage drop on radio activity
APP_ERROR_CHECK(rc);

Would performing the sampling on radio activity disable fix the issue:

rc = radio_notification_init(3, NRF_RADIO_NOTIFICATION_TYPE_INT_ON_INACTIVE , NRF_RADIO_NOTIFICATION_DISTANCE_800US); //Changed from Active to Inactive to combat Voltage drop on radio activity
APP_ERROR_CHECK(rc);

RE: SAADC read on VDD giving a dip in value every 1 to 1.5 hours for approx 2 mins

Ameer Usman — Sun, 05 Jan 2020 05:25:52 GMT

I am using a CR2016 Coin cell.

RE: SAADC read on VDD giving a dip in value every 1 to 1.5 hours for approx 2 mins

Vidar Berg — Thu, 02 Jan 2020 13:14:43 GMT

you beat me to it - I didn't refresh the page before posting:)

RE: SAADC read on VDD giving a dip in value every 1 to 1.5 hours for approx 2 mins

Vidar Berg — Thu, 02 Jan 2020 13:12:37 GMT

Hi,

What kind of battery are you using? Particularly coin-cell batteries can have high internal resistance under load and thus cause higher voltage drop when peripherals such as the RADIO and CPU are running.

Thanks,

Vidar

RE: SAADC read on VDD giving a dip in value every 1 to 1.5 hours for approx 2 mins

Otso Jousimaa — Thu, 02 Jan 2020 13:03:25 GMT

Have you checked if there is loading on battery before sampling? For example the radio can cause significant voltage droop on coin cells, there's some oscilloscope captures at blog.ruuvi.com/ruuvi-firmware-part-13-battery-measurement-synchronized-to-radio-a0a4dba1e002