The Program and Debug Interface (PDI) is a Microchip proprietary interface for external programming and on-chip debugging of a device. PDI Physical is a 2-pin interface providing a bidirectional half-duplex synchronous communication with the target device.

When designing an application PCB, which includes a Microchip 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