12.2 Troubleshooting Guide

Table 12-1. Troubleshooting Guide
Target type/family	Problem	Possible causes	Solution
N/A	Power LED does not light up	DC supply voltage is insufficient or of incorrect polarity	Check that you are using the correct power supply provided with the kit. If you are using another power supply, ensure that it has a center-positive connector.
Atmel megaAVR and Atmel AVR XMEGA	JTAG debugging starts, then suddenly fails	The JTAG Disable bit in the MCUCSR register has been inadvertently written by the application	Hold reset low to regain control and change the code so that the JTAG Disable bit is not written
Atmel megaAVR and Atmel AVR XMEGA	After using the Atmel AVR ONE! to download code to the device, the emulator no longer works	1. The JTAG ENABLE fuse has been disabled. 2. The programming interface is still active. It is not possible to use both OCD and programming at the same time.	1. Program the JTAG ENABLE fuse. 2. Close the Programming interface, then enter emulation mode.
Atmel megaAVR, Atmel AVR XMEGA, and Atmel tinyAVR	Atmel AVR ONE! is detected by Atmel Studio or other software front-end, but it will not connect to target device	JTAG: JTAG ENABLE Fuse is not programmed debugWIRE: DWEN Fuse is not programmed	JTAG: Use an other programming interface to program the JTAG ENABLE Fuse debugWIRE: Use an other programming interface to program the DWEN Fuse
Atmel megaAVR, Atmel AVR XMEGA, and Atmel AVR UC3	JTAG Debugging and programming is unstable, or does not work at all	For some target board configurations there might be some ringing on the interface lines	Add series resistors on the JTAG lines, especially TCK, but series resistors could be useful on TMS and TDI too. A value of about 68Ω will in most cases be suitable. Note that you might have to reduce the JTAG clock frequency after adding the series resistors.
N/A	Atmel Studio gives a message that no voltage is present	1. No power on target board. 2. Vtref not connected. 3. Target voltage too low.	1. Apply power to target board. 2. Make sure your JTAG connector includes the Vtref signal. 3. Make sure the target power supply is able to provide enough power.
Atmel megaAVR	OCD fuse is disabled, but using the Atmel AVR ONE!, OCD is still possible	The AVR ONE! will automatically program the OCD fuse if it is disabled	This is correct operation
Atmel megaAVR and Atmel tinyAVR	Some I/O registers are not updated correctly in Atmel Studio I/O view	When non-intrusive read back is not possible, the Atmel AVR ONE! will not update this location in the Atmel Studio I/O view	Read this I/O location into a temporary register, and view it there during debugging. See the chapter "Special Considerations" for information about which registers affected by this.
Atmel tinyAVR and Atmel megaAVR with debugWIRE support	SPI programming after a debugWIRE session is not possible	When the debugWIRE Interface is enabled the SPI Interface is disabled	Re-enable the SPI Interface as described in the section "Connecting to Target through the debugWIRE Interface". Use command line software to re-enable SPI interface.
Atmel tinyAVR and Atmel megaAVR with debugWIRE support	Neither SPI nor debugWIRE connection works	The SPI and debugWIRE interfaces are disabled. DebugWIRE will not work if the lockbits are programmed.	Connect to target with High Voltage Programming. Enable SPI or debugWIRE and clear lockbits if using debugWIRE.
Atmel megaAVR, Atmel tinyAVR, Atmel AVR XMEGA, and Atmel AVR UC3	Error messages, or other strange behavior when using debugWIRE or JTAG	Target is running outside Safe Operation Area. Maximum frequency vs. V_CC.	Make sure the target is running within the Safe Operation Area as described in the chapter "Electrical Characteristics" in the datasheet for the actual part. Lower the frequency and/or increase the voltage.

N/A

Power LED does not light up

DC supply voltage is insufficient or of incorrect polarity

Check that you are using the correct power supply provided with the kit. If you are using another power supply, ensure that it has a center-positive connector.

Atmel megaAVR and Atmel AVR XMEGA

JTAG debugging starts, then suddenly fails

The JTAG Disable bit in the MCUCSR register has been inadvertently written by the application

Hold reset low to regain control and change the code so that the JTAG Disable bit is not written

Atmel megaAVR and Atmel AVR XMEGA

After using the Atmel AVR ONE! to download code to the device, the emulator no longer works

1. The JTAG ENABLE fuse has been disabled.

2. The programming interface is still active. It is not possible to use both OCD and programming at the same time.

1. Program the JTAG ENABLE fuse.

2. Close the Programming interface, then enter emulation mode.

Atmel megaAVR, Atmel AVR XMEGA, and Atmel tinyAVR

Atmel AVR ONE! is detected by Atmel Studio or other software front-end, but it will not connect to target device

JTAG: JTAG ENABLE Fuse is not programmed

debugWIRE: DWEN Fuse is not programmed

JTAG: Use an other programming interface to program the JTAG ENABLE Fuse

debugWIRE: Use an other programming interface to program the DWEN Fuse

Atmel megaAVR, Atmel AVR XMEGA, and Atmel AVR UC3

JTAG Debugging and programming is unstable, or does not work at all

For some target board configurations there might be some ringing on the interface lines

Add series resistors on the JTAG lines, especially TCK, but series resistors could be useful on TMS and TDI too. A value of about 68Ω will in most cases be suitable. Note that you might have to reduce the JTAG clock frequency after adding the series resistors.

N/A

Atmel Studio gives a message that no voltage is present

1. No power on target board.

2. Vtref not connected.

3. Target voltage too low.

1. Apply power to target board.

2. Make sure your JTAG connector includes the Vtref signal.

3. Make sure the target power supply is able to provide enough power.

Atmel megaAVR

OCD fuse is disabled, but using the Atmel AVR ONE!, OCD is still possible

The AVR ONE! will automatically program the OCD fuse if it is disabled

This is correct operation

Atmel megaAVR and Atmel tinyAVR

Some I/O registers are not updated correctly in Atmel Studio I/O view

When non-intrusive read back is not possible, the Atmel AVR ONE! will not update this location in the Atmel Studio I/O view

Read this I/O location into a temporary register, and view it there during debugging. See the chapter "Special Considerations" for information about which registers affected by this.

Atmel tinyAVR and Atmel megaAVR with debugWIRE support

SPI programming after a debugWIRE session is not possible

When the debugWIRE Interface is enabled the SPI Interface is disabled

Re-enable the SPI Interface as described in the section "Connecting to Target through the debugWIRE Interface". Use command line software to re-enable SPI interface.

Atmel tinyAVR and Atmel megaAVR with debugWIRE support

Neither SPI nor debugWIRE connection works

The SPI and debugWIRE interfaces are disabled. DebugWIRE will not work if the lockbits are programmed.

Connect to target with High Voltage Programming. Enable SPI or debugWIRE and clear lockbits if using debugWIRE.

Atmel megaAVR, Atmel tinyAVR, Atmel AVR XMEGA, and Atmel AVR UC3

Error messages, or other strange behavior when using debugWIRE or JTAG

Target is running outside Safe Operation Area. Maximum frequency vs. V_CC.

Make sure the target is running within the Safe Operation Area as described in the chapter "Electrical Characteristics" in the datasheet for the actual part. Lower the frequency and/or increase the voltage.