nRF takes a long time 3-6 minutes to boot

RE: nRF takes a long time 3-6 minutes to boot

bjorn-spockeli — Mon, 08 Oct 2018 06:32:13 GMT

The Secure Bootloader will remain in bootloader mode upon start up if the GPREGRET register or the bootloader button pin(Pin 16) is asserted, see dfu_enter_check() in nrf_bootloader.c. You can try to debug the bootloader to see if it starts the application or remains in bootloader mode.

RE: nRF takes a long time 3-6 minutes to boot

Andrew Ong — Fri, 05 Oct 2018 18:23:35 GMT

But this is not about whether RTT connects to my application. My application does not start at all. There are LEDs on the board that turn blue when the application starts. On one board, it takes many minutes for them to turn blue and on the other, they turn blue instantly. I was wondering if there is something like the GPREGRET register in the secure bootloader that makes it wait there for many minutes.

RE: nRF takes a long time 3-6 minutes to boot

bjorn-spockeli — Fri, 05 Oct 2018 11:55:08 GMT

It is possible to place the Segger RTT control block at the same location in RAm for both the application and bootloader. Then you do not need to reconnect after the bootloader jumps to the application. See this case for the instructions:

https://devzone.nordicsemi.com/f/nordic-q-a/30310/easy-way-to-merge-bootloader-and-application-rtt-output

RE: nRF takes a long time 3-6 minutes to boot

Andy — Fri, 05 Oct 2018 10:01:55 GMT

The boot behavior should be the same. You're probably experiencing a known RTT issue where it fails to seamlessly transition from bootloader to app. Try again and if nothing happens after pressing "g", type "connect".