Freescale Semiconductor MCF51QE128RM manual IIC Status Register Iics, Iics Field Descriptions, Tcf

Models: MCF51QE128RM

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13.3.4IIC Status Register (IICS)

R

W

Reset

7

6

5

 

4

3

2

1

0

TCF

IAAS

BUSY

 

ARBL

0

SRW

IICIF

RXAK

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

1

0

0

 

0

0

0

0

0

 

= Unimplemented or Reserved

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Figure 13-6. IIC Status Register (IICS)

 

 

Table 13-7. IICS Field Descriptions

 

 

 

Field

 

Description

 

 

7

Transfer Complete Flag. This bit is set on the completion of a byte transfer. This bit is only valid during or

TCF

immediately following a transfer to the IIC module or from the IIC module.The TCF bit is cleared by reading the

 

IICD register in receive mode or writing to the IICD in transmit mode.

 

0

Transfer in progress

 

1

Transfer complete

 

 

6

Addressed as a Slave. The IAAS bit is set when the calling address matches the programmed slave address or

IAAS

when the GCAEN bit is set and a general call is received. Writing the IICC register clears this bit.

 

0

Not addressed

 

1

Addressed as a slave

 

 

5

Bus Busy. The BUSY bit indicates the status of the bus regardless of slave or master mode. The BUSY bit is set

BUSY

when a start signal is detected and cleared when a stop signal is detected.

 

0

Bus is idle

 

1

Bus is busy

 

 

4

Arbitration Lost. This bit is set by hardware when the arbitration procedure is lost. The ARBL bit must be cleared

ARBL

by software by writing a 1 to it.

 

0

Standard bus operation

 

1

Loss of arbitration

 

 

2

Slave Read/Write. When addressed as a slave, the SRW bit indicates the value of the R/W command bit of the

SRW

calling address sent to the master.

 

0

Slave receive, master writing to slave

 

1

Slave transmit, master reading from slave

 

 

1

IIC Interrupt Flag. The IICIF bit is set when an interrupt is pending. This bit must be cleared by software, by writing

IICIF

a 1 to it in the interrupt routine. One of the following events can set the IICIF bit:

 

 

• One byte transfer completes

 

 

• Match of slave address to calling address

 

 

• Arbitration lost

 

0

No interrupt pending

 

1

Interrupt pending

 

 

0

Receive Acknowledge. When the RXAK bit is low, it indicates an acknowledge signal has been received after the

RXAK

completion of one byte of data transmission on the bus. If the RXAK bit is high it means that no acknowledge

 

signal is detected.

 

0

Acknowledge received

 

1

No acknowledge received

 

 

 

MCF51QE128 MCU Series Reference Manual, Rev. 3

2-268

Freescale Semiconductor

Page 268
Image 268
Freescale Semiconductor MCF51QE128RM manual IIC Status Register Iics, Iics Field Descriptions, Tcf