BLE Nano no longer Low Power


I followed BLE Nano - Low Power Consumption to program the NanoV2 in low power mode and got ~0.2mA while advertising and a bit less while connected.

However some time later, while working on a very low power supply for the board, the NanoV2 switched into a high power >2.5mA mode with no change to the sketch.

Now when the Nano powers up the orange led flashes for 30sec and then goes solid. Reflashing the low power sketch does not fix this.

Questions: i) What mode is the Nano V2 in to cause the high power and orange led to flash
2) How do I get the chip back into low power mode.

I am guessing that there is some uncleared interrupt or continually occurring interrupt that causes ble.waitForEvent(); to trigger all the time, But cannot tell what is happening using the Arduino IDE since Serial is Turned off as part of the low power sketch.


Did you try to flash the nrf52_EraseChip.hex file?


No I did not try that recovery option. Thanks for the suggestion I will keep it in mind once the basic problem is fixed.
Re-flashing is not a viable fix once the NanoV2 is deployed with a power supply that only provides 0.6mA.
Note the supply is not a battery but a current limited supply from mains power, so when the chip goes into high power mode it just stops working immediately and never starts again
I need permanent fix that will last.


It seems that the nRF52 chip can get into debug mode by its self which draws mA’s instead of uA’s
Once you have programmed your chip, connect a 470R and 1nF, in parallel, directly from SWCLK to GND to stop noise triggering debug.

Also I have published a detailed tutorial on how to program the NanoV2 for very low power <100uA all the time, advertising and connected send/receive
You can use either the NanoV2 programmer or this tutorial shows you how to use a BlackMagic Probe to program the NanoV2.
There is a free app that will generate the low power Arduino Sketch for you that lets you show control menus and plot and log data on your Android mobile, using pfodApp.