The Program and Debug Interface (PDI) is an Atmel proprietary interface for external programming and on-chip debugging of a device. PDI Physical is a 2-pin interface providing a bi-directional half-duplex synchronous communication with the target device.
When designing an application PCB, which includes an Atmel AVR with the PDI interface, the pinout shown in Figure 1 should be used. The 6-pin standoff adapter provided with the AVR ONE! kit can then be used to connect the AVR ONE! probe to the application PCB.
Figure 1. PDI Header Pinout
