3.3.1.2 JTAG Header (mounted)
The 10-pin JTAG header is a standard pinout JTAG connector. When connecting the Atmel AVR Dragon JTAG header to an external target, the signals are level converted to match the target board voltage. This is done automatically. Note that the AVR Dragon will not power the target through the JTAG interface. The target needs to be powered through a dedicated power supply or by powering it using the VCC connector (5.0V max. 300mA). AVR Dragon needs to sense the target voltage on pin 4 on the JTAG connector.
| Pin | Signal | I/O | Description |
|---|---|---|---|
| 1 | TCK | Output | Test Clock, clock signal from AVR Dragon to target JTAG port |
| 2 | GND | - | Ground |
| 3 | TDO | Input | Test Data Output, data signal from target JTAG port to AVR Dragon |
| 4 | VTref | Input | Target reference voltage. VDD from target used to control level-converters. |
| 5 | TMS | Output | Test Mode Select, mode select signal from AVR Dragon to target JTAG port |
| 6 | nSRST | In/Out-put | Open collector output from adapter to the target system reset. This pin is also an input to the adapter so that the reset initiated on the target may be reported to the AVR Dragon. |
| 7 | - | - | Not connected |
| 8 | - | - | Not Connected |
| 9 | TDI | Output | Test Data Input, data signal from AVR Dragon to target JTAG port |
| 10 | GND | - | Ground |