ICSP 6-pin (AVR) Pinout
The standard AVR in-circuit serial programming header (2x3, 2.54mm).
Overview
The 6-pin ICSP/ISP header is the modern standard for programming Atmel/Microchip AVR microcontrollers (and Arduino's ICSP header) over SPI. It is a 2x3 header on 0.1 inch pitch.
A programmer drives MOSI, MISO, SCK and RESET while sensing target voltage on VCC; the chip is held in reset during programming.
Pinout
| Pin | Name | Function | Description |
|---|---|---|---|
| 1 | MISO | SPI / DATA | Master-In Slave-Out: data from target to programmer |
| 2 | VCC / VTG | POWER | Target supply / voltage reference (sensed) |
| 3 | SCK | SPI / CLK | SPI serial clock from programmer |
| 4 | MOSI | SPI / DATA | Master-Out Slave-In: data/code to target |
| 5 | RESET | SIGNAL | Target reset, held low during programming |
| 6 | GND | GND | Ground |
Notes
- MISO is called PDO and MOSI PDI in some AVR datasheets.
- Pin 2 is usually a voltage reference (sensed), not a power source, on most programmers.
Reference: Microchip Atmel-ICE User Guide (SPI header) / Pololu· verified 2026-06-27