14.1.4 Functional Overview
Each device connected to an I2C bus is recognized by a unique address. Each device can operate as either a
transmitter or a receiver, depending on the function of the device. A device connected to the I2C bus can also
be considered as the master or the slave when performing data transfers. A master device is the device that
initiates a data transfer on the bus and generates the clock signals to permit that transfer. During this transfer,
any device addressed by this master is considered a slave. The I2C module supports the multi-master mode, in
which one or more devices capable of controlling an I2C bus can be connected to the same I2C bus.
For data communication, the I2C module has a serial data pin (SDA) and a serial clock pin (SCL), as shown in
. These two pins carry information between the C28x device and other devices connected to the I2C
bus. The SDA and SCL pins both are bidirectional. They each must be connected to a positive supply voltage
using a pull-up resistor. When the bus is free, both pins are high. The driver of these two pins has an open-drain
configuration to perform the required wired-AND function.
There are two major transfer techniques:
• Standard Mode: Send exactly n data values, where n is a value you program in an I2C module register. See
the I2CCNT register in
for more information.
• Repeat Mode: Keep sending data values until you use software to initiate a STOP condition or a new START
condition. See the I2CMDR register in
The I2C module consists of the following primary blocks:
• A serial interface: one data pin (SDA) and one clock pin (SCL)
• Data registers and FIFOs to temporarily hold receive data and transmit data traveling between the SDA pin
and the CPU
• Control and status registers
• A peripheral bus interface to enable the CPU to access the I2C module registers and FIFOs.
• A clock synchronizer to synchronize the I2C input clock (from the device clock generator) and the clock on
the SCL pin, and to synchronize data transfers with masters of different clock speeds
• A prescaler to divide down the input clock that is driven to the I2C module
• A noise filter on each of the two pins, SDA and SCL
• An arbitrator to handle arbitration between the I2C module (when it is a master) and another master
• Interrupt generation logic, so that an interrupt can be sent to the CPU
• FIFO interrupt generation logic, so that FIFO access can be synchronized to data reception and data
transmission in the I2C module
shows the four registers used for transmission and reception in non-FIFO mode. The CPU writes
data for transmission to I2CDXR and reads received data from I2CDRR. When the I2C module is configured
as a transmitter, data written to I2CDXR is copied to I2CXSR and shifted out on the SDA pin one bit at a time.
When the I2C module is configured as a receiver, received data is shifted into I2CRSR and then copied to
I2CDRR.
Inter-Integrated Circuit Module (I2C)
836
TMS320x2806x Microcontrollers
SPRUH18I – JANUARY 2011 – REVISED JUNE 2022
Copyright © 2022 Texas Instruments Incorporated
Содержание TMS320 2806 Series
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