Raspberry Pi Pinout

GPIO 3 (I2C Clock)

Alt0Alt1Alt2Alt3Alt4Alt5
I2C1 SCLSMI SA2DPI HSYNCAVEOUT HSYNCAVEIN HSYNC
  • Physical/Board pin 5
  • GPIO/BCM pin 3
  • Wiring Pi pin 9
  • GPIO/BCM pin 1 on Rev 1 ( very early ) Pi

SCL (I2C1 Clock) is one of the i2c pins on the Pi, learn more about i2c.

SCL includes a fixed, 1.8 kΩ pull-up to 3.3v, which means this pin is not suitable for use as a general purpose IO where no pull-up resistor is desired.