While measuring a signal I incidently made a short on the back of the JTAG connector.
The uC is still working, I can see this as the LED that I have in my application is still blinking, but unfortunately JTAG communication does not work anymore.
I already checked the ATMEL ICE programmer with another controller and it works without problems, so programmer is excluded.
I already measured all components that are between the JTAG connector and the uC JTAG pins and everything seems ok, so I am out of ideas.
Now I am checking on the scope the JTAG lines an a good microcontroller while doing some simple operation like reading the Signature Bytes or reading the Fuses, to have an idea how the JTAG signal should look like.
And the final question, is it possible that the uC works, but the JTAG from the microcontroller doesn't work anymore???