i2c scanner

Mastering Arduino Part 12 cover: I2C, Addressing a Bus, with SDA and SCL, 7-bit address, pull-ups and ACK/NACK panels
Mastering Arduino Part 12: I2C, Addressing a Bus
Arduino DIY Electronics
Learn how I2C shares two wires among many devices: open-drain lines and pull-ups, 7-bit addresses, the Wire library, scanning for devices, and putting two on one bus.