6P6C I2C Connector Standard

In order to allow many of our I2C peripherals to easily communicate with each other, we standardized on a standard 6 position, 6 conductor (6P6C) modular connector, colloquially referred to (incorrectly) as an RJ11, RJ14, or RJ25.

Pinout

Pin
Color
Alt Color1
Signal
1
White
White/Green
/OEN - Outputs enabled when low
2
Black
White/Orange
I2C SDA
3
Red
Blue/White
Ground
4
Green
White/Blue
/RESET - Resets external peripherals when low.  Alternatively, on some boards, can be used for +5V supply (<1mA)
5
Yellow
Orange/White
I2C SCL
6
Blue
Green/White
/IRQ - Input to the CPU, when pulled low indicates some peripheral is signaling an interrupt to be handled
Note 1: Alternate color reflects use with more modern twisted pair cables. These are not recommended, as I2C is not differential and thus twisted pair only adds additional capacitive effects.