3.2 PDI

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.

Use the pinout shown in the figure below when designing an application PCB with an AVR with the PDI interface included.
Figure 3-2. PDI Header Pinout

Direct Connection to a Standard 6-pin 100-mil PDI Header

Use the included 100-mil 6-pin flat cable to connect directly to a board supporting the PDI header type. Note the pin-1 marking on the cable, and ensure to line it up with the pin-1 marking on the AVR Programming Adapter.

Note: The RESET pin is used for clocking the PDI. It is important to bypass or avoid any circuitry that can distort the clock signal during programming or debugging, such as capacitors and external reset sources.
Table 3-2. PDI Pin Description
MPLAB® Debugger/Programmer Hardware Tools PDI Pin Mapping
Pin # Pin Name Header Pin # Name Description
1 TVPP
2 TVDD 2 VCC Target voltage reference
3 GND 6 GND Common ground
4 PGD 1 PDI_DATA PDI data input/output
5 PGC
6 TAUX 5 PDI_CLK PDI clock input/RESET pin
7 TTDI
8 TTMS