Raspberry Pi allows for software I2C. To enable software I2C, add `dtoverlay=i2c-gpio,bus=3` to `/boot.config.txt`. The software I2C would be available on `bus` no `3` where the `SDA` is on pin `GPIO23`/`BCM 16` and `SCK` is on pun `GPIO24`/`BCM 18`. In this tests, the `SH1106` is using software I2C on bus `3`.