REGOUT0 set to 3.3V fail buttonless DFU

[inya_lake]

Hi, 

 I've nrf52840, s140 with SDK17.2 and I was able to set REGOUT0 to 3.3V in 2 ways.

if (NRF_UICR->REGOUT0 != UICR_REGOUT0_VOUT_3V3)
{
NRF_NVMC->CONFIG = NVMC_CONFIG_WEN_Wen << NVMC_CONFIG_WEN_Pos;
while (NRF_NVMC->READY == NVMC_READY_READY_Busy){}
NRF_UICR->REGOUT0 = UICR_REGOUT0_VOUT_3V3;

NRF_NVMC->CONFIG = NVMC_CONFIG_WEN_Ren << NVMC_CONFIG_WEN_Pos;
while (NRF_NVMC->READY == NVMC_READY_READY_Busy){}
}

or 

nrfjprog.exe --memwr 0x10001304  --val 0xFFFFFFFD

After that I do buttonless DFU and noticed that failed.

If I keep REGOUT0 to 1.8V, buttonless DFU work. Any idea what is causing DFU to fail when I set regout0 to 3.3V?

My DFU was based on below instructions.

github.com/.../nRF52832-buttonless-dfu-development-tutorial

Thanks,

[Amanda Hsieh]

Hi Lu, 

It seems strange. We suspect the issue could be something else altogether, but there is not enough information to say much. Could you elaborate on what way it fails. Logs from the DFU master, and also the bootloader (RTT log from using _debug example bootloader project) are generally helpful. 

-Amanda H.

[inya_lake]

Hi Amanda,

Thank you. Turned out it was related to my hardware. For some reason, that particular unit was not erasing UICR registers properly. Please close ticket.