Possible Ways to Brick?

[Nick]

Hello,

I have a board with an RFDuino on it which uses a Nordic nRF51822 internally. We are seeing a few of them auto-brick when the input voltage dips too low.

My first guess is that it is doing an EEPROM write even when the voltage dips or something, but I am just wondering what can brick these? Any known errata for this?

Basically it is running off of a big battery and as long as it stays above 2.9-ish volts, it works forever it seems. When it goes to 2.8v or so, sometimes it stops responding and then never turns on again. I haven't written the software but I am trying to get the code to look at.

[F800]

We can reprogram the chip, using RF Digital's programmer. We can connect Nordic's Dev Kit to the board and verify that the device is able to respond' to JLink commands. What we cannot do is successfully execute Simblee code that appears to load correctly with RF Digital's programmer. I've even taken that one-way-ticket to erase one failing device's FLASH using the Nordic/JLink and verified that JLink can load/verify/execute good code. I conclude that the nRF51822(s) are functional but that something is corrupting either the RF Digital code or the SoftDevice. Since the Simblee is locked, however, I can think of no fix that does not erase the FLASH and that leaves us with a 'bricked' Simblee.

[Nick]

I have a JLink as well so I will give this a try. It appears that we are seeing the same thing over two of their products. Maybe their bootloader is doing something to the NVM that it shouldn't be...