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Intel
®
IXP45X and Intel
®
IXP46X Product Line of Network Processors—I2C Bus Interface Unit
Intel
®
IXP45X and Intel
®
IXP46X Product Line of Network Processors
Developer’s Manual
August 2006
898
Order Number: 306262-004US
12
Arbitration
Loss
Detected
Interrupt
Enable
Arbitration Loss Detected Interrupt Enable:
0 = Disable interrupt.
1 = Enables the I
2
C unit to interrupt the IXP45X/IXP46X network
processors
upon losing arbitration while in master mode.
0
RW
11
Slave STOP
Detected
Interrupt
Enable
Slave STOP Detected Interrupt Enable:
0 = Disable interrupt.
1 = Enables the I
2
C unit to interrupt the IXP45X/IXP46X network
processors
upon detecting a STOP condition while in slave mode.
0
RW
10
Bus Error
Interrupt
Enable
Bus Error Interrupt Enable:
0 = Disable interrupt.
1 = Enables the I
2
C unit to interrupt the IXP45X/IXP46X network
processors
for the following I
2
C bus errors:
• As a master transmitter, no Ack was detected after a byte was
sent.
• As a slave receiver, the I
2
C unit generated a Nack pulse.
Note:
Software is responsible for guaranteeing that misplaced
START and STOP conditions do not occur. See
“Glitch Suppression Logic” on page 896
0
RW
09
IDBR Receive
Full Interrupt
Enable
IDBR Receive Full Interrupt Enable:
0 = Disable interrupt.
1 = Enables the I
2
C unit to interrupt the IXP45X/IXP46X network
processors
when the IDBR has received a data byte from the I
2
C
bus.
0
RW
08
IDBR
Transmit
Empty
Interrupt
Enable
IDBR Transmit Empty Interrupt Enable:
0 = Disable interrupt.
1 = Enables the I
2
C unit to interrupt the IXP45X/IXP46X network
processors
after transmitting a byte onto the I
2
C bus.
0
RW
07
General Call
Disable
General Call Disable:
0 = Enables the I
2
C unit to respond to general call messages.
1 = Disables I
2
C unit response to general call messages as a slave.
This bit must be set when sending a master mode general call
message from the I
2
C unit.
0
RW
06
I
2
C Unit
Enable
I
2
C Unit Enable:
0 = Disables the unit and does not master any transactions or
respond to any slave transactions.
1 = Enables the I
2
C unit (defaults to slave-receive mode).
Software must guarantee the I
2
C bus is idle before setting this bit.
0
RW
05
SCL Enable
SCL Enable:
0 = Disables the I
2
C unit from driving the SCL line.
1 = Enables the I
2
C clock output for master mode operation.
0
RW
04
Master Abort
Master Abort: used by the I
2
C unit when in master mode to generate
a STOP without transmitting another data byte.
0 = The I
2
C unit transmits STOP using the STOP ICR bit only.
1 = The I
2
C unit sends STOP without data transmission.
When in Master transmit mode, after transmitting a data byte, the
ICR’s Transfer Byte bit is cleared and IDBR Transmit Empty bit is set.
When no more data bytes need to be sent, setting master abort bit
sends the STOP. The Transfer Byte bit (03) must remain clear.
In master-receive mode, when a Nack is sent without a STOP (STOP
ICR bit was not set) and the IXP45X/IXP46X network processors
do
not send a repeated START, setting this bit sends the STOP. Once
again, the Transfer Byte bit (03) must remain clear.
0
RW
Register
I
2
C Control Register (Sheet 2 of 3)
Bits
Name
Description
Reset
Value
Access