Inter-Integrated Circuit (I2C) is a protocol for communicating with low-speed peripherals.
The BeagleBone Black hardware has two I2C buses. Each bus has
an I2C Master connected to two bidirectional lines, serial data line
(SDA), and serial clock (SCL). These two lines are connected to a
pair of pins, such as
I2C1_SDA (P9_18) and
(P9_17), on the GPIO header.
You can connect multiple I2C devices, such ADCs, LCDs, and sensors, to the I2C pins on the BeagleBone Black hardware. Each I2C device on an I2C bus must have a unique address. Most devices have a default address that the manufacturer assigns. If the address is not unique, follow the manufacturer instructions for reconfiguring the address. Often, you can reconfigure the address using a pair of jumpers on the device. The BeagleBone Black hardware supports only 7-bit addresses. This 7-bit address space supports 128 unique addresses.
1.8 kΩ resistors pull up the I2C pins on the BeagleBone
Black hardware. The I2C devices must support
not draw more current than the BeagleBone Black hardware maximum.