RE: Custom Device always boots into DfuTarg Mode and cannot load program.

BendaEng — Thu, 25 Jul 2019 14:42:56 GMT

Hi Vidar,

Thanks for the reply! We did do some testing in a debug session with a BL652 (nRF52832) dev kit with our second custom board and didn't find anything out of the norm compared to our first custom board.

However, we did some circuit review and found that in our first custom board we used a NMOS transistor to reset the BL652 (pin 7, nReset) (other MCU operates at 5v, BL652 at 3.3v) but in this new board we accidentally changed it to a PMOS but didn't change the circuit source or drain. We removed both of these on both versions of the boards and also held the states of the reset pin to known logic levels and it didn't change the behavior.

This led us to believe that the Laird Board BL652 had some internal problems (clock, power management, etc) which were causing the reset. After changing the BL652 module out, it solved the problem. So, long story short, it was a bad BL652. But we also found a small circuit error in the process.

Thanks for offering a suggestion to try!

RE: Custom Device always boots into DfuTarg Mode and cannot load program.

Vidar Berg — Thu, 25 Jul 2019 08:30:44 GMT

Hi,

Is it possible to attach a debugger to the custom board then start a debug session with the bootloader project to see what condition is causing it to stay in DFU mode? E.g., see if any of the checks in nrf_bootloader.c->dfu_enter_check() returns 'true'. Maybe there's a CRC mismatch that makes the nrf_dfu_app_is_valid() check fail.