BCM 3 (I2C Clock)
|I2C1 SCL||SMI SA2||DPI HSYNC||AVEOUT HSYNC||AVEIN HSYNC|
- Physical pin 5
- BCM pin 3
- Wiring Pi pin 9
- BCM pin 1 on Rev 1 ( very early ) Pi
SCL (i2c Clock) is one of the i2c pins on the Pi, learn more about i2c.
SCL includes a fixed, 1.8 kohms pull-up to 3.3v, which means this pin is not suitable for use as a general purpose IO where no pullup resistor is desired.