The term I²C stands for Inter-Integrated Circuit, represents a serial data bus and describes how devices communicate with each other and exchange data. The data is transmitted via two lines, the SDA (Serial Data) and the SCL (Serial Clock) line. The SDA line is used to transmit the actual data. The SCL line only specifies the clock frequency and signals when a bit is present on the data line. On the I2C bus, all devices communicate via the so-called master/slave principle. Hereby, the entire communication is controlled by a single device, the micro:bit (master), and all other devices only wait for permission to transmit and are therefore called slaves. I²C is used in the Joy-Car for communication and control of the infrared sensors (IO Expander) and the motor control unit (PWM controller).
FOR EXPERTS: The addresses 0x70 (PWM controller) and 0x38 (IO expander) are used to control the systems via I2C.