I2C

How it is used

Pronounced 'I-squared-C' or 'I-two-C', and also written I²C. Both lines need pull-up resistors. Engineers talk about the device address, bus speed (100 kHz or 400 kHz), master and slave devices (now often called controller and target) and a device that doesn't acknowledge (NACK).

Example sentences

1. The temperature sensor doesn't respond on I2C; check that its address is 0x48.

2. We run the I2C bus at 400 kHz because the cable to the display is short.

Common collocations

• I2C bus
• I2C address
• I2C sensor
• I2C scanner

Related terms

• SPIShort for Serial Peripheral Interface: a fast synchronous serial bus with a clock line, two data lines and a separate chip-select line for each device. It is used for flash memory, displays and ADCs.
• UARTShort for universal asynchronous receiver-transmitter: a hardware block that sends and receives serial data over two lines, TX and RX, without a shared clock.
• pull-up resistorA resistor that connects a signal line to the supply voltage so that the line stays at a defined high level when nothing is driving it, instead of floating.
• clock signalA regular square wave that sets the timing of a digital circuit so that all its parts act in step. Its frequency, for example 16 MHz, sets how fast a processor runs.
• microcontrollerA small computer on a single chip, with a processor, memory and input/output peripherals. It runs firmware to control devices such as appliances, sensors and motors.

More terms: Digital Electronics and Microcontrollers

• GPIO
• ADC
• PWM
• firmware