nRF52832 is it possible to clear CONFIG_GPIO_AS_PINRESET via software?

[Philip]

I have CONFIG_GPIO_AS_PINRESET defined in my project (both bootloader DFU and main program), so pin 21 is setup as hardware reset.

I would like to disable this function for a test, so would any of the following be possible;

1 - Is it possible to turn it of in software by modifying NRF_UICR->PSELRESET ?

2 - If not would it be possible to remove the define from just the main program and rebuild?

3 - Would the chip need a full erase, and the define removed from the DFU project before re-build / re-programme?

Thanks

[Einar Thorsrud]

Hi,

Option 3 (which is like option 2 + full chip erase) is the cleanest and only sensible way in most cases. Option 2 in itself is not possible since you must do a full chip erase to erase the UICR. Simply programming new firmware that is built without CONFIG_GPIO_AS_PINRESET will not reset the PSELRESET registers so that they will keep their original value (enabling pin reset).

Though likely not relevant for you, option 1 can also be useful on a few special occasions. If you have a device in the field and want to disable pin reset, that would have to be done in a way that does not involve a chip erase. In that case,  you can use the following code snippet to programmatically disable pin reset by writing an invalid configuration to one of the PSELRESET registers. This is a hack, though, and should only be used when that is the only option.

/** Function to disable pin reset by writing an invalid configuration (all 0) to PSELRESET[1] */
static void disable_pin_reset(void)
{
    // Only perform if needed (which is the first time this code runs)
    if (NRF_UICR->PSELRESET[1] != 0)
    {
        NRF_LOG_INFO("Disabling pin reset.");

        NRF_NVMC->CONFIG = NVMC_CONFIG_WEN_Wen;
        while (NRF_NVMC->READY == NVMC_READY_READY_Busy){}

        NRF_UICR->PSELRESET[1] = 0;

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

        // System reset is needed to update UICR registers.
        NVIC_SystemReset();
    }
}

[Philip]

Thanks Einar,

Sounds good, I will give the hack a try also as it might be useful for some units already in the field.

Phil