Bootloader doesn't load application on power-on

Question

I have a small problem with my bootloader + application on NRF52832. I'm using SDK 12.2.0 with S132 v3.0.0. 
 When the device loses power, and power is then re-applied, the bootloader doesn't start the application. If I however issue a reset through SWD, the application is started. 
 Everything else is working as expected (BLE DFU firmware update etc.). I know there isn't a lot to go on, but I'm hoping there is a simple explanation.

dingari · Accepted Answer

Well, I think I finally found the culprit. 
 I use hardware debouncing for the buttons on my board (couple of resistors and a capacitor). During initial power up of the board, the capacitor might not be fully charged by the time nrf_dfu_enter_check is called, leading the application to read a low level on the bootloader button pin, and thus staying in bootloader mode. 
 On my board a 100nF capacitor is initially charged through 200 kOhms, so a 20ms delay ( 100*10^(-9) * 200*10^3 ) at the top of main in my bootloader code is sufficient to make this problem go away.