Custom nRF52832 module can't connect J-Link anymore after flashing Zephyr program

RE: Custom nRF52832 module can't connect J-Link anymore after flashing Zephyr program

PaKa — Thu, 26 Oct 2023 08:14:41 GMT

Did you try to run recover with the reset line pulled low? It needs to be kept low from before applying VDD until the recover command has been executed. Letting it go high before that will allow the regulator to change to DCDC mode and this will disable the programming interface.

RE: Custom nRF52832 module can't connect J-Link anymore after flashing Zephyr program

nerdybee — Wed, 25 Oct 2023 17:35:38 GMT

Thanks for your answer. Checking our project configuration, it seems like there's a variable CONFIG_GPIO_AS_PINRESET set to 'y' by default. Wouldn't this effectively make my P21 act as the RESET pin, rather than GPIO?

RE: Custom nRF52832 module can't connect J-Link anymore after flashing Zephyr program

PaKa — Wed, 25 Oct 2023 14:24:48 GMT

Default function for the reset pin is a a GPIO. This will be the case unless you have specifically set it up to be the reset pin, https://infocenter.nordicsemi.com/topic/com.nordic.infocenter.nrf52832.ps.v1.1/uicr.html?cp=5_2_0_13_0_59#register.PSELRESET-0

You can try to run the recover feature without cycling the power then. If you have a SEGGER jlink and not the DK then the power supplies are independent and you can change the VDD level on the fly, this as the SEGGER devices have level shifters (our DKs do not have these).

RE: Custom nRF52832 module can't connect J-Link anymore after flashing Zephyr program

nerdybee — Wed, 25 Oct 2023 14:10:20 GMT

Also, just to confirm, for the second option, you mean running nrfjprog --recover in the terminal over and over while turning the module on and off repeatedly? Would this not be damaging since the JLINK connector would remain connected to the DK, while the module would be powered off for some fraction of time?

RE: Custom nRF52832 module can't connect J-Link anymore after flashing Zephyr program

nerdybee — Wed, 25 Oct 2023 14:04:54 GMT

Thank you so much for confirming my suspicions - this is very helpful! Can you explain in a bit more detail what you mean about the RESET being activated as RESET vs GPIO? Our code doesn't address P21 (the reset pin in the Fanstel BC832) at all, but it is routed in the PCB to the reset line from the DK. Putting a scope probe to it shows the RESET line being HIGH all the time, except for then the RESET button on the DK is pressed while the module is connected to the DK, in which case it transiently goes low and then back up high.

RE: Custom nRF52832 module can't connect J-Link anymore after flashing Zephyr program

PaKa — Wed, 25 Oct 2023 13:55:55 GMT

1: this is a very likely cause of the problem. If you enable the DCDC and don't have the inductor mounted then the devices should be bricked.

2: If the reset line has been activated as a reset (and not as an GPIO) then keeping the device in reset when applying power will stop the device from enabling the DCDC. You can then perform a chip erase and device is back to normal. If reset is set up as GPIO then your best bet is to try to run the recover function multiple times while preferably cycling the power supply. If you are very lucky you may get the parts erased and then you are good.

Make sure the target voltage on VTref is the same as on the DK, 3.0V, as any other voltage will fail.