Problem with JTAG connection on UC3A3256 using JTAG ICE MK3

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Hi,

 

I am trying to JTAG program a new board which has a UC3A3256. I power everything from USB and the USB is connected to the UC3 and I see the DFU bootloader in windows as a device. A stupid thing I did was to change the placement of the bootloader pin from PB10 to PB1 so I cant use the bootloader after the first programming unless I can change the user pages and that needs JTAG.

 

So the problem I am having is that the JTAG ICE MK3 does not detect any device. Voltage is ok, but no device. I do not know very much about JTAG signals and what should happen when. Is there a specification or has anyone make a log of how it should look if it works? I have tripple checked the signals and the schematic is the same as the EVK board and the layout looks good as well.

 

This is generation 5 of the board so it has been working for me for a very long time (~5 years with ~75 boards made). I cant see what I have changed, it should all be the same except routing which should be better on this board since its the first time I cared about trace impedance. Is there a problem using the JTAG ICE MK3 perhaps? I did buy a ISP MK2 for my 8-bit processors because I thought the ICE MK3 was not stable enough.

 

Any support on problems with the ICE MK3 or on what the signals on the JTAG should look would be appreciated.

 

Thanks!

/Anders

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I tried programming an old UC3A0512 board I have with the JTAG ICE mk3 and Atmel Studio 6.2. Both programming and singlestepping works fine, so I guess it would work with the A3 as well.

 

Regarding JTAG signalling, TDO is the output from the A3 back to the JTAG ICE 3, so if this is not toggling the A3 is not responding at all for some reason. You could also check that nothing else is driving the RESET_N line low while the debugger is connected.