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Topic: What programmer to use to unbrick a board? (Read 147 times) previous topic - next topic

liudr

I bricked a board with an 1284P-AU on it. I was changing low fuse and my connection wasn't great (a few jumper wires held by hand) so the MCU is bricked. I was using Nick's hex uploader sketch. It reported success but was not able to enter programming mode afterwards. I carefully did one more board without losing connections so the second board was good.

Now I wonder what programmer(s) can unbrick an ATMEL MCU with possibly corrupt low fuse settings? I only have the arduino style ICSP header brought out. I don't have much experience with programmers other than arduino boards programming arduino boards :-[

Thanks.

westfw

If it's only the low fuse that was corrupted, you can probably fix it by injecting clock into the appropriate xtal pin.
http://www.avrfreaks.net/forum/tutsoft-recovering-locked-out-avr

liudr

Karma! Thanks westfw! It turned out that I had a solder bridge between XTAL2 and its neighbor (GND!). So the crystal never oscillated I bet. That explained why after reporting success in programming low fuse, the hex uploader was unable to communicate with the chip. According to the link you provided, the internal 1MHz oscillation (8MHz/8) was used when I programmed the fuse. Once it is programmed, the chip needs to excite the crystal but oops the short. I didn't leave it powered for too long so I am hoping it won't develop some permanent damage. Anyway, your reference is still very relevant, made me look at the pins and I've saved the link for future reference. I also found out my edu version signal generator can only go up to 150KHz, not 1MHz. :)

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