Freescale Semiconductor MC9S08PT60, Reference Manual

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I2C_S field descriptions (continued)
Field Description
• Match of slave address to calling address including primary slave address, range slave address,
alert response address, second slave address, or general call address.
• Arbitration lost
• In SMBus mode, any timeouts except SCL and SDA high timeouts
0 No interrupt pending
1 Interrupt pending
0
RXAK
Receive Acknowledge
0 Acknowledge signal was received after the completion of one byte of data transmission on the bus
1 No acknowledge signal detected
18.3.5 I2C Data I/O register (I2C_D)
Address: 3070h base + 4h offset = 3074h
Bit 7 6 5 4 3 2 1 0
Read
DATA
Write
Reset 0 0 0 0 0 0 0 0
I2C_D field descriptions
Field Description
DATA Data
In master transmit mode, when data is written to this register, a data transfer is initiated. The most
significant bit is sent first. In master receive mode, reading this register initiates receiving of the next byte
of data.
NOTE: When making the transition out of master receive mode, switch the I2C mode before reading the
Data register to prevent an inadvertent initiation of a master receive data transfer.
In slave mode, the same functions are available after an address match occurs.
The C1[TX] bit must correctly reflect the desired direction of transfer in master and slave modes for the
transmission to begin. For example, if the I2C module is configured for master transmit but a master
receive is desired, reading the Data register does not initiate the receive.
Reading the Data register returns the last byte received while the I2C module is configured in master
receive or slave receive mode. The Data register does not reflect every byte that is transmitted on the I2C
bus, and neither can software verify that a byte has been written to the Data register correctly by reading it
back.
In master transmit mode, the first byte of data written to the Data register following assertion of MST (start
bit) or assertion of RSTA (repeated start bit) is used for the address transfer and must consist of the
calling address (in bits 7-1) concatenated with the required R/W bit (in position bit 0).
Chapter 18 Inter-Integrated Circuit (I2C)
MC9S08PT60 Reference Manual, Rev. 4, 08/2014
Freescale Semiconductor, Inc. 515