4.4 TPI Interface

The Tiny Programming Interface is featured on the tinyAVR® devices with the lowest pin count.

The following figure shows the standard TPI connector supplied along with the Microchip programmer device. Only three pins on the device are required for use of this interface; RESET, TPICLK, and TPIDATA. The latter two pins are multiplexed with regular I/O pins.

Figure 4-7. Standard TPI Header
The RESET pin can be reconfigured as an I/O pin by programming the RSTDISBL fuse of the device. This disables the reset functionality and requires +12V to be applied to Reset for programming to work. Only a few programming tools are capable of generating this voltage.
Note: Refer to the respective programmer user guide for more information about the capabilities and physical interface of TPI.