JTAG connector below shows how to connect the JTAG ICE probe to the AVR Butterfly.


The JTAG connector must be mounted on the back-side of the AVR Butterfly.

The JTAG connector is used for the ATmega169 built in JTAG interface. The pinout of the connector is shown in JTAG Connector and is compliant with the pin out of the JTAG ICE available from Atmel. Connecting a JTAG ICE to this connector allows On-chip Debugging of the ATmega169.

More information about the JTAG ICE and the On-chip Debugging can be found in the AVR JTAG ICE User Guide, which is available at the Atmel web site, http://www.atmel.com/.


Pin 7, NC(VCC) is the Vsupply pin for the JTAG. This pin is not connected because the JTAG would draw power from the battery on the AVR Butterfly. Pin 8, NC(BS2) and the pin 10, GND(XTAL1) can be modified serve as the BS2 and XTAL1 pin during High-voltage Parallel Programming. For more details see 3.2.2 High-voltage Parallel Programming.


It is highly recommended to apply external power (3,1 4,5V), when using the JTAG to save the battery. See External power for how to connect external power. Make sure to disable the OCD-fuse after a debugging session, due to power consumption. The OCD-fuse will be disabled if pressing on the "Stop Debugging" button in AvrStudio4, before disconnecting the JTAG ICE probe from the AVR Butterfly.

External power can be applied at pin 9 and 10 at both PORTB and PORTD, see PORTB and PORTD pinout for the pinout.

If the JTAG are not in use, the four JTAG pins can be used as input for the ADC channels ADC[4:7]. See the ATmega169 datasheet for more information, available from http://www.atmel.com/.