[2] Devices on the bus

Submitted by rgcustodio on June 10, 2007 - 12:32pm.
I2C bus


Fig 1. The I2C bus, 1 MASTER , 3 SLAVEs, and the required pull-up resistors.


There are two kinds of device on the I2C bus:

MASTER - node that always controls the clock line

SLAVE - node that is not in control of the clock line


The most common setup is 1 MASTER and multiple SLAVEs on the I2C bus. Both MASTER and SLAVE can transfer data over the I2C bus, but that transfer is always controlled by the MASTER.

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about pull-up resistors

Microcontrollers generally have internal software-based pull-up resistors on the SCL and SDA lines. Check your microcontroller datasheet on how to enable them.