Erased J-link firmware from interface MCU

[Anesh]

I was trying to update J-link firmware (using link [https://devzone.nordicsemi.com/question/170895/nrf52832-jlink-stop-working-after-entering-bootloader-mode/] ) into interface MCU (MCU between PC and nRF52 uC responsible for downloading code into nRF52 uC) but accidentally erased bootloader firmware. Now, nRFGo Studio is not detecting segger device Id. Led next to interface MCU is not blinking. No mass Storage device is appearing on my PC.

Please suggest me how to fix this. Thanks!

[Sridhar Jonnavittula]

Anesh,

Can you explain how have you erased bootloader firmware? This bootloader firmware is in Interface MCU flash only right?

Thanks,

Sridhar

[MartinBL]

There might be several ways to do it, but here is one:

The MCU chip (an ATSAM3U2CA-AU) is equipped with an ERASE pin. If this pin is pulled high for some milliseconds the flash will be erased. On earlier versions of the nRF5x DKs this pin was pulled to GND with a 1k resistor. Unfortunately, the pin is also located right next to a pin which is connected to VDD on the nRF5x DKs. Hence, if you accidentally short these neighboring pins, e.g. by having loose jumper wires flying around, you risk erasing the flash. On later versions of the DKs however, the ERASE pin is tied directly to GND and a short will turn off the MCU before the flash is erased.