Battery Power problem

[mich_x]

I am using nRF52840 board. And I used keil and nrfjprog, both successfully flashed the hex file onto the board with USB connected. The example I used is ble_app_uart_c.

My program runs fine, but once I disconnected the USB cable and use the battery. The board does not work. I have changed the battery. I have tried and encounter this problem on several nRF52840 boards. I have put the power switch on VDD instead of USB when using a battery.

I even used a power profiler and the board lights up the led on power profiler which means the voltage on pin is right. BUT the program does not run. Or it runs for a very short time and died.

[Bjørn Kvaale]

What kind of battery are you using? Are you plugging the battery into external supply (P21) (see link)?

[mich_x]

I am using coin battery and I am not plugging the battery into external supply

[Bjørn Kvaale]

Are you using SDK 14? You are flashing ble_app_uart_pca10056_s140.hex onto the nrf52840, right? Also, can you check that SW6 switch is on Default please? Have you tried running a different example? Could you try running the ble_app_hrs example found under: "nRF5_SDK_14.0.0_3bcc1f7/examples/ble_peripheral/ble_app_hrs/hex/" and running the HRM example in nrf toolbox for iOS or Android? Would be interesting to see if that works.

[mich_x]

I tried the ble_app_hrs example and the battery works. But my project still failed. So my guess is could it be something to do with the uart process. Because I used the uart in my project. Could it cause the halt due to none cable connected.

[Bjørn Kvaale]

Have you compared your uart implementation with the uart example posted here? If you think there's something wrong with your uart, it might be a good idea to compare your implementation to Nordic's implementation.