13.3.5IIC Data I/O Register (IICD)

R

W

Reset

7

6

5

4

 

3

2

1

0

 

 

 

 

DATA

 

 

 

 

 

 

 

 

 

 

 

0

0

0

0

 

0

0

0

0

 

 

 

 

 

 

 

 

 

 

Figure 13-7. IIC Data I/O Register (IICD)

 

Table 13-8. IICD Field Descriptions

 

 

Field

Description

 

 

7–0

Data — In master transmit mode, when data is written to the IICD, a data transfer is initiated. The most significant

DATA

bit is sent first. In master receive mode, reading this register initiates receiving of the next byte of data.

 

 

NOTE

When transitioning out of master receive mode, the IIC mode should be switched before reading the IICD register to prevent an inadvertent initiation of a master receive data transfer.

In slave mode, the same functions are available after an address match has occurred.

The TX bit in IICC must correctly reflect the desired direction of transfer in master and slave modes for the transmission to begin. For instance, if the IIC is configured for master transmit but a master receive is desired, reading the IICD does not initiate the receive.

Reading the IICD returns the last byte received while the IIC is configured in master receive or slave receive modes. The IICD does not reflect every byte transmitted on the IIC bus, nor can software verify that a byte has been written to the IICD correctly by reading it back.

In master transmit mode, the first byte of data written to IICD following assertion of MST is used for the address transfer and should comprise of the calling address (in bit 7 to bit 1) concatenated with the required R/W bit (in position bit 0).

13.3.6IIC Control Register 2 (IICC2)

R

W Reset

7

6

5

4

3

2

1

0

GCAEN

ADEXT

0

0

0

AD10

AD9

AD8

 

 

 

 

 

 

 

 

 

 

 

 

 

 

0

0

0

0

0

0

0

0

 

 

 

 

 

 

 

 

= Unimplemented or Reserved

Figure 13-8. IIC Control Register (IICC2)

MCF51QE128 MCU Series Reference Manual, Rev. 3

Freescale Semiconductor

2-269

Page 269
Image 269
Freescale Semiconductor MCF51QE128RM IIC Data I/O Register Iicd, IIC Control Register 2 IICC2, Iicd Field Descriptions