Intel
®
81341 and 81342—I
2
C Bus Interface Units
Intel
®
81341 and 81342 I/O Processors
Developer’s Manual
December 2007
936
Order Number: 315037-002US
05
0
2
Arbitration Loss Detected
: used during multi-master operation.
0 = Cleared when arbitration is won or never took place.
1 = Set when the I
2
C unit loses arbitration.
04
0
2
Slave STOP Detected
:
0 = No STOP detected.
1 = Set when the I
2
C unit detects a STOP while in slave-receive or slave-transmit mode.
03
0
2
I
2
C
Bus Busy
:
0 = I
2
C bus is idle or the I
2
C unit is using the bus (i.e., unit busy).
1 = Set when the I
2
C bus is busy but the 81341 and 81342
I
2
C unit is not involved in the transaction.
02
0
2
Unit Busy
:
0 = I
2
C unit not busy.
1 = Set when the 81341 and 81342
I
2
C unit is busy. This is defined as the time between the first START
and STOP.
01
0
2
Ack/Nack Status
:
0 = The I
2
C unit received or sent an Ack on the bus.
1 = The I
2
C unit received or sent a Nack.
This bit is used in slave transmit mode to determine when the byte transferred is the last one. This bit is
updated after each byte and Ack/Nack information is received.
00
0
2
Read/Write Mode
:
0 = The I
2
C unit is in master-transmit or slave-receive mode.
1 = The I
2
C unit is in master-receive or slave-transmit mode.
This is the R/W# bit of the slave address. It is automatically cleared by hardware after a stop state.
Table 589. I
2
C Status Register x — ISRx (Sheet 2 of 2)
Bit
Default
Description
PCI
IOP
Attributes
Attributes
28
24
20
16
12
8
4
0
31
rv
na
rv
na
rv
na
rv
na
rv
na
rv
na
rv
na
rv
na
rv
na
rv
na
rv
na
rv
na
rv
na
rv
na
rv
na
rv
na
rv
na
rv
na
rv
na
rv
na
rv
na
rc
na
rc
na
rc
na
rc
na
rc
na
rc
na
rc
na
ro
na
ro
na
ro
na
ro
na
Unit #
0
1
2
Intel XScale
®
processor internal bus address
offset
+2504H
+2524H
+2544H
Attribute Legend:
RV = Reserved
PR = Preserved
RS = Read/Set
RW = Read/Write
RC = Read Clear
RO = Read Only
NA = Not Accessible