custom board bootlaoder not entering DFU mode even when there is no application installed

[Hussein A Hazime]

Hello , i'm trying to implement the OTA DFU function in my custom designed board. I'm using NRF52 series. I started by flashing the flash I uploaded the softdevice132 v2 via the NRFgo and then I uploaded the ble dual bank example bootloader from SDKv11 and edited the file so that it supports the single bank mode as indicated in previous questions.

The problem I'm facing is that I tried the files on the DEVboard everything works fine the procedure as follows: 1- Flash the chip 2- upload softdevice 3- upload the bootloader

no application is installed, when I turn the DEVboard on the NRF chip enters the DFU mode automatically and I can see the advertisement on the mobile app.

when I do the same procedure on the custom board knowing that no application is uploaded the Bluetooth is not advertising and I can't find the DFUTARG in the mobile application.

I'm using an external clock for the BLE should I change any config files, why isn't the bootloader entering the DFU mode, since there is no app installed.

[AmbystomaLabs]

Sounds like clock differences. It's the most common reason for the softdevice to not start. It's also possible that either your external RTC crystal or external 32MHz crystal have issues. You should inspect the placement and soldering of both and their load capacitors.

[Hussein A Hazime]

The custom board is functional, I uploaded the normal application and it worked perfectly, even the Bluetooth.

[AmbystomaLabs]

Sorry, don't have an answer for you then. Based on what I have read and done, as long as the flag in the bootloader isn't set (which is the case when you haven't loaded an app through it) it should go straight to DFU mode. You could try doing an erase all on the custom board before programming it. It is possible the flag got set during some of your work and it isn't getting written over so it thinks valid code is out there.

Here is some info on the DFU flag: devzone.nordicsemi.com/.../

[bjorn-spockeli]

Are you able to debug the bootloader, i.e. check whether you enter the bootloaders main function or not?

[Hussein A Hazime]

The problem was with the clock configuration of the Bluetooth softdevice init method static void ble_stack_init(bool init_softdevice)in the SOFTDEVICE_HANDLER_APPSH_INIT(&clock_lf_cfg, true); i had to change the used clock to match my requirements.