I2Cx_S field descriptions (continued)
Field
Description
0
Bus is idle
1
Bus is busy
4
ARBL
Arbitration Lost
This bit is set by hardware when the arbitration procedure is lost. The ARBL bit must be cleared by
software, by writing a one to it.
0
Standard bus operation.
1
Loss of arbitration.
3
RAM
Range Address Match
This bit is set to 1 by any of the following conditions:
• Any nonzero calling address is received that matches the address in the RA register.
• The RMEN bit is set and the calling address is within the range of values of the A1 and RA registers.
NOTE: For the RAM bit to be set to 1 correctly, C1[IICIE] must be set to 1.
Writing the C1 register with any value clears this bit to 0.
0
Not addressed
1
Addressed as a slave
2
SRW
Slave Read/Write
When addressed as a slave, SRW indicates the value of the R/W command bit of the calling address sent
to the master.
0
Slave receive, master writing to slave
1
Slave transmit, master reading from slave
1
IICIF
Interrupt Flag
This bit sets when an interrupt is pending. This bit must be cleared by software by writing a 1 to it, such as
in the interrupt routine. One of the following events can set this bit:
• One byte transfer, including ACK/NACK bit, completes. An ACK or NACK is sent on the bus by
writing 0 or 1 to TXAK after this bit is set in receive mode.
• Match of slave address to calling address including primary slave address, range slave address or
general call address.
• Arbitration lost
• I2C bus stop detection if the STOPIE bit in the Input Glitch Filter register is 1
NOTE:
To clear the I2C bus stop detection interrupt: In the interrupt service routine,
first clear the STOPF bit in the Input Glitch Filter register by writing 1 to it, and
then clear the IICIF bit. If this sequence is reversed, the IICIF bit is asserted
again.
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
Memory map and register descriptions
KL02 Sub-Family Reference Manual, Rev. 2.1, July 2013
478
Freescale Semiconductor, Inc.