I2C (Inter-Integrated Circuit) Framework

I2C (Inter-Integrated Circuit) is a simple serial protocol that connects multiple devices in a master-slave relationship. Multiple master devices may share a single bus. The same device may function as both a master and a slave in different transactions. The I2C specification defines these transfer speed ranges:

• ≤ 100 Kbit/s
• ≤ 400 Kbit/s
• ≤ 3.4 Mbit/s

The I2C framework is intended to facilitate consistent implementation of I2C interfaces. The framework consists of the following parts:

hardware/i2c/*

The hardware interface.

lib/i2c

The resource manager layer.

<hw/i2c.h>

A public header file that defines the hardware and application interfaces.

The most common application of the I2C bus is low-bandwidth access to a slave device's registers, such as:

• programming an audio codec
• programming a RTC
• reading a temperature sensor
• reading from an EPROM

Typically, only a few bytes are exchanged on the bus.

You can implement the I2C master as a single-threaded resource manager, or as a dedicated application. The primary advantages of a resource manager interface are:

• It presents a clear, easy-to-understand interface to the application developer.
• It mediates between accesses by multiple applications to one or more slave devices.
• It enforces consistency between different I2C interfaces.

For a dedicated I2C-bus application, a hardware access library is more efficient. The hardware interface, which defines the interface to this library, is useful as a starting point for developers and facilitates maintenance and code portability.