30.3.8 I2C Range Address register (I2Cx_RA)
Address: Base a 7h offset
Bit
7
6
5
4
3
2
1
0
Read
Write
Reset
0
0
0
0
0
0
0
0
I2Cx_RA field descriptions
Field
Description
7–1
RAD
Range Slave Address
This field contains the slave address to be used by the I2C module. The field is used in the 7-bit address
scheme. Any nonzero write enables this register. This register's use is similar to that of the A1 register, but
in addition this register can be considered a maximum boundary in range matching mode.
0
Reserved
This field is reserved.
This read-only field is reserved and always has the value 0.
30.4 Functional description
This section provides a comprehensive functional description of the I2C module.
30.4.1 I2C protocol
The I2C bus system uses a serial data line (SDA) and a serial clock line (SCL) for data
transfers. All devices connected to it must have open drain or open collector outputs. A
logic AND function is exercised on both lines with external pull-up resistors. The value
of these resistors depends on the system.
Normally, a standard instance of communication is composed of four parts:
1. START signal
2. Slave address transmission
3. Data transfer
4. STOP signal
The STOP signal should not be confused with the CPU STOP instruction. The following
figure illustrates I2C bus system communication.
Functional description
KL02 Sub-Family Reference Manual, Rev. 2.1, July 2013
482
Freescale Semiconductor, Inc.