9-26 Intel® PXA26x Processor Family Developer’s Manual
Inter-Integrated Circuit Bus Interface Unit
9.9.4 I2C Status Register

The ISR signals I2C interrupts to the processor i nterr upt con tro ller. Software can use the ISR bits to

check the status of the I2C unit and bus. ISR bits (bits 9-5) are updated after the ACK/NAK bit is

completed on the I2C bus.

The ISR also clears the following interrupts signalled from the I2C un it:

IDBR receive full
IDBR transmit empty
Slave address detected
Bus error detected
STOP condition detect
Arbitration lost
3TB
TRANSFER BYTE:
Used to send/receive a byte on the I2C bus.
0 – Cleared by I2C unit when the byte is sent/received.
1 – Send/receive a byte.
The processor can monitor this bit to determine when the byte transfer is completed. In
master or slave mode, after each byte transfer, including ACK/NAK bit, the I2C unit holds
the SCL line low (inserting wait states) until the Transfer Byte bit is set.
2 ACKNAK
ACK/NAK CONTROL:
Defines the type of ACK pulse sent by the I2C unit when in master-receive mode.
0 – The I2C unit sends an ACK pulse after it receives a data byte.
1 – The I2C unit sends a negative ACK (NAK) after it receives a data byte.
The I2C unit automatically sends an ACK pulse when it responds to its slave address or
when it responds in slave-receive mode, independent of the ACK/NAK control bit setting.
1STOP
STOP:
Initiates a STOP condition after the next data byte on the I2C bus is transferred in master
mode. In master-receive mode, the ACK/NAK control bit must be set along with this bit. See
Section9.3.3.3, “STOP Condition” for more details on the STOP state.
0 – Do not send a STOP.
1 – Send a STOP.
0START
START:
Initiates a START condition to the I2C unit when in master mode. See Section9.3.3.1,
“START Condition” for more details on the START state.
0 – Do not send a START.
1 – Send a START.

Table 9-11. I2C Control Register - ICR (Sheet 3 of 3)

Physical Address
4030_1690 I2C Control Register I2C
Bit 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
Reserved
FM
UR
SADIE
ALDIE
SSDIE
BEIE
IRFIE
ITEIE
GCD
IUE
SCLE
MA
TB
ACKNAK
STOP
START
Reset 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0