68HC(9)12DG128 Rev 1.0
MOTOROLA
Inter-IC Bus
251
Inter-IC Bus
Inter-IC Bus
Contents
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .251
IIC Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .252
IIC System Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .254
IIC Protocol . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .254
IIC Register Descriptions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .258
IIC Programming Examples . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .267
Introduction
The Inter-IC Bus (IIC or I
2
C) is a two-wire, bidirectional serial bus that
provides a simple, efficient method of data exchange between devices.
Being a two-wire device, the IIC minimizes the need for large numbers
of connections between devices, and eliminates the need for an address
decoder.
This bus is suitable for applications requiring occasional
communications over a short distance between a number of devices. It
also provides flexibility, allowing additional devices to be connected to
the bus for further expansion and system development.
The interface is designed to operate up to 100kbps with maximum bus
loading and timing. The device is capable of operating at higher baud
rates, up to a maximum of clock/20, with reduced bus loading. The
maximum communication length and the number of devices that can be
connected are limited by a maximum bus capacitance of 400pF.
1-iicbus