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 1 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, if I2C_C2[RMEN] = 1:
• Any nonzero calling address is received that matches the address in the RA register.
• 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 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 if FACK is 0. An ACK or NACK is sent on the
bus by writing 0 or 1 to TXAK after this bit is set in receive mode.
• One byte transfer, excluding ACK/NACK bit, completes if FACK is 1.
• 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
• I2C bus stop or start detection if the SSIE bit in the Input Glitch Filter register is 1
NOTE:
To clear the I2C bus stop or start detection interrupt: In the interrupt service
routine, first clear the STOPF or STARTF 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
Chapter 45 Inter-Integrated Circuit (I2C)
K22F Sub-Family Reference Manual , Rev. 3, 7/2014
Freescale Semiconductor, Inc.
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