I2C

To enable all 6 I2C interfaces on Raspberry Pi 4, add this to boot config.txt

# Uncomment some or all of these to enable the optional hardware interfaces
#dtparam=spi=on
#dtparam=i2s=on
dtparam=i2c_arm=on,i2c_arm_baudrate=400000
dtoverlay=i2c6
dtoverlay=i2c5
dtoverlay=i2c4
dtoverlay=i2c3
dtoverlay=i2c1
dtoverlay=i2c0

The GPIO Pinouts for each bus are

I2C Bus	GPIO SDA	GPIO SCL
0	0	1
1	2	3
3	4	5
4	8	9
5	12	13
6	22	23