MCF548x Reference Manual, Rev. 3
28-6 Freescale Semiconductor
76543210
R ICF IAAS IBB IAL 0 SRW IIF RXAK
W
Reset10000001
Reg
Addr
MBAR + 0x8F0C

Figure 28-5. I2C Status Register (I2SR)

Table 28-6. I2SR Field Descriptions

Bits Name Description
7 ICF Data transferring bit. While one byte of data is transferred, ICF is cleared.
0 Transfer in progress
1 Transfer complete. Set by the falling edge of the ninth clock of a byte transfer.
6 IAAS I2C addressed as a slave bit. The CPU is interrupted if I2CR[IIEN] is set. Next, the CPU must check
SRW and set its TX/RX mode accordingly. Writing to I2CR clears this bit.
0 Not addressed.
1 Addressed as a slave. Set when its own address (I2ADR) matches the calling address.
5 IBB I2C bus busy bit. Indicates the status of the bus.
0 Bus is idle. If a STOP signal is detected, IBB is cleared.
1 Bus is busy. When START is detected, IBB is set.
4 IAL Arbitration lost. Set by hardware in the following circumstances. (IAL must be cleared by software by
writing zero to it.)
SDA sampled low when the master drives high during an address or data-transmit cycle.
SDA sampled low when the master drives high during the acknowledge bit of a data-receive cycle.
A start cycle is attempted when the bus is busy.
A repeated start cycle is requested in slave mode.
A stop condition is detected when the master did not request it.
3 Reserved, should be cleared.
2 SRW Slave read/write. When IAAS is set, SRW indicates the value of the R/W command bit of the calling
address sent from the master. SRW is valid only when a complete transfer has occurred, no other
transfers have been initiated, and the I2C module is a slave and has an address match.
0 Slave receive, master writing to slave (on the SDA signal).
1 Slave transmit, master reading from slave (on the SDA signal).
1 IIF I2C interrupt. Must be cleared by software by writing a zero to it in the interrupt routine.
0No I
2C interrupt pending
1 An interrupt is pending, which causes a processor interrupt request (if IIEN = 1). Set when one of
the following occurs:
Complete one byte transfer (set at the falling edge of the ninth clock)
Reception of a calling address that matches its own specific address in slave-receive mode
Arbitration lost
0 RXAK Received acknowledge. The value of SDA during the acknowledge bit of a bus cycle.
0 An acknowledge signal was received after the completion of 8-bit data transmission on the bus
1 No acknowledge signal was detected at the ninth clock.