Table 5. Common problems resolutions

ProblemReasonSolution
Errors when programming or debugging Atmel AVR UC3 devices over JTAGRinging on the TCK line might lead to incorrect detection of rising edges on TCK. This is depending on the target board, and has shown to be a problem when connected to an AVR UC3 target on some Atmel STK600 configurations.Add a series resistor on TCK (typically 68 Ohm) or add a capacitor of at least 1 nF between TCK and ground. The series resistor solution is the preferred one since it does not stress the Dragon level converters as much as the capacitor solution, but both solutions should work.
Signature Bytes read as 0x00 0x00 0x00SPI Frequency is to high.Lower SPI frequency in the Debugging properties (Property Pages item on View menu)
Not able to communicate with device through debugWIRERESET pullup resistor too smallRemove or increase the pull-up value to 10 kΩ or more.
Not able to communicate with device through debugWIREDecoupling capacitor destroys communication on RESET lineRemove decoupling capacitor on reset line during debugWIRE debugging
debugWIRE communication fails when using Atmel STK500RESET line strongly tied to VCCRemove RESET jumper on STK500 to allow AVR Dragon to control the line.
After successfully enabling the DWEN fuse, AVR Dragon is not able to enter debug modeRESET line strongly tied to VCCRemove RESET jumper on STK500 to allow AVR Dragon to control the line.
Target voltage is read as 0V for on-board targetsAVR Dragon gets no reference voltage to the target voltage sensing. Target voltage is sensed from either pin 2 on the SPI header or pin 4 on the JTAG header.In order to get reference voltage to the level converters of AVR Dragon, connect Pin 2 or 4 or 6 on the VCC header to pin 2 on SPI header or pin 4 on the JTAG header[a]
Target voltage is read as 0V for off-board targets.AVR Dragon gets no reference voltage to the target voltage sensing. Target voltage is sensed from either pin 2 on SPI header or pin 4 on the JTAG header.Connect the target voltage from the target board to pin 2 on SPI header or pin 4 on the JTAG header.
Not able to set SPI frequencyAVR Dragon is not reading any target voltage.See above
SPI/PP/HVSP programming failsAVR Dragon is not reading any target voltageSee above
Not able to connect to AVR Dragon, and status led is yellowAVR Dragon firmware upgrade failed, or firmware is corrupt.For information on how to upgrade the firmware, see the Atmel Studio user guide.
Programming or debug sessions fails, resetting the AVR DragonThe target circuitry draws too much power from the AVR DragonTry to power the circutry from an external source in stead of the AVR Dragon

[a] Note that VCC pins on AVR Dragon are set to 5V and this procedure should therefore not be used for off-board targets.