Bricked SamD20? WDT fuse mistakes.

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I have been trying to get my wdt and started playing around with the fuses on my D20E17. I ticked "WDT-Always on" and ticked "WDT-Enabled" and since then I have been unable to program or even read the device signature of my micro.

 

I have 2 Atmel Ice's in front of me Ive been testing with on both Atmel 6.2 and 7. I also (just to try) pulled everything out and closed atmel studio, waited for 30 seconds and connected everything back as this usually fixes my issue. But this time my device just seems dead.

 

Is it possible that the wdt is resetting the chip before the ICE can even read the signature? I thought the SWD interface would've been outside of the application/fuse section of the micro (coming from AVR). As such it wouldn't have any issues at least reading the sigature?

 

Any suggestions would be super!
 

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I believe you are correct in that the ICE cannot connect before being lost from the WDT if the timeout is to fast. I think there should be halt the pc on reset via the tool although I didn't see this option for SWD on the Atmel ICE.

 

Perhaps this can try to recover it this way: Try using the atprogram from the cmd line to re-program the fuses. You need to hold the reset line active (manually), issue the atprogram command then release the reset line.

 

Example to write the fuses could be (you need to check the exact data you want for the fuses)

atprogram -t atmelice -i swd -d atsamd20e17 write -fs --values 8FE9E0DA5DFFFFFF

Last Edited: Thu. Dec 17, 2015 - 05:15 PM
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Interestingly enough. I came in this morning with a feshly restart PC, tried the first ICE on 0Hz (Default) to read signature nothing. Tried again on 2MHz (max) nothing.

 

Then did the same with the second, nothing at 0Hz and then I managed to read and refuse with the second ICE.

 

So I am not quite sure what has happened here, but im happy =]

 

2nd ICE ftw.

 

Else yea Ive been wanting to know the cmd line options for using the ice, similar to using avrdude with the usbasp's etc. Thanks for the suggestion!