atxmega256A3U vs. atxmega256A3 fuse settings for BODLVL

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Xmega ‘noob here. 

 

I have an atxmega256A3AU part on a board running at 3.3V with a 12Mhz crystal.  My Atmel studio is version 6.2.1502, service pack1.   I am using a MKII programmer, had the part set to atxmega256A3U and I set the BODLVL to 3V0 in the “device programming” mode.  Once I did that, I lost communication to the processor.  The crystal is no longer oscillating.

 

I think where I messed up is that I had should have set the device programming to atxmega256A3 for this part.  (not atxmega256A3U)  The atxmega256A3 does not have a fuse setting for 3V0.  (it has a 2V9 and 3V2)  Since this is my second time doing this, I really don’t want to replace the IC on the board again.  Is there a way for me to resume communication with the atxmega part?

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If it helps, this is a screen capture of the fuse settings right before I lost communication with the board.

( I was using a MKII programmer, not the J-tag ICE shown in the screen capture.  The screen capture is from the software developer)

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Last Edited: Wed. Jan 14, 2015 - 04:54 PM
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Solved my issue:

I set Fuse Byte 5 to 0xF8.  The lowest 3 bits of this byte control the brown out level.

On table 9-2 of the datasheet, this sets the brownout to 3.4V.  So, I attached a current limited power supply and started upping the voltage on the micro.

When the input voltage reached about 3.55V, I could again communicate with the atxmega.