Correction of a typing mistake:
nTRST = JTAG line 8 ( not 10 )
With my Arduino Mega ADK, and JTAGICE3, it was necessary configure my system for ISP communications ( with the help of the adapter supplied with JTAGICE3, and by AVR Studio 5.1, "Tools / Programming" to enable the JTAGEN fuse bit ( the BOOTRST fuse bit was already set )- I was told so in a AVRFreaks forum thread :-).
Then the instructions of the one-before posting in this thread helped me to configure my system for JTAG communications, after correcting the wiring mistake: I am now able to read the fuse bits by JTAG.
for complete instructions.
Indeed, this thread was very helpful for me :-).
In the one-before posting, VTRef = JTAG line 4 is connected to VCC.
Should I connect this line on the Arduino Mega to
- 5 Volts
- or Vin ( which might be 9 Volts, as this is said to be the voltage of the power supply, if I power the board not by USB but by an external power supply ) ?
I understand to use analog inputs for data coming from the debugger. So if you name "Analog pin 4" I suppose that you mean the "Analog in A4" pin at the lower edge of the device in the photo, right ?
But with "TDO,3, Test Data Out (data transmitted from the target device into the AVR ONE!)" an analog input is used for output of analog (?) data. So may we really use "Analog in A7" for that ? And how does that work ? Or is this "just for JTAG" and Analog-out no standard feature of ATmega boards ?
The ATxmega, however, indeed has DAC on board, btw, as explained in many examples.