NRF51 current abrupt change

[liu]

hello, I uses NRF51822 to make a beacon with RTC. When it works initially, the churrent is small about 330uA，but after a few minutes it becomes 1.1mA and stable. I donn't konow why.

[Stian Røed Hafskjold]

Are you using GPIOTE IN event for the g-sensor interrupt pin? This consumes current in idle mode. You should configure to use GPIO PORT event.

For the 1.1mA I suspect that the chip enter debug mode. Please see Kenneth's answer in this one: https://devzone.nordicsemi.com/f/nordic-q-a/16530/issue-with-nrf51-unexpectedly-entering-debug-mode

You can also post a hex file if you want. Then I can do some measurements here.

[liu]

hello,

Thanks for your help.This is my hex file with S110.6406.nrf51422_xxac_s110.hex

[Stian Røed Hafskjold]

I can see that the IDLE current is fine. About 4 µA. The reason for the 30µA is an app-timer or similar that is waking the chip up every 30 ms. Also, you calibrate every 250ms which is more than necessary. 4 seconds should be fine if the temperature is stable.

The chip never enters the 1.1mA consumption here. I'm pretty sure this is the chip accidentally entering debug mode. There's an issue with this on the nRF51 and we recommend to put an extra pull down resistor on SWDCLK.