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 the figure below should be used. One of the 6-pin adapters provided with the Atmel-ICE kit can then be used to connect the Atmel-ICE probe to the application PCB.
Figure 1. PDI Header Pinout
