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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
892
Order Number: 306262-004US
• Sets the ISR general call address detected bit
• Sets the ISR slave address detected bit
• Interrupts (when enabled) the IXP45X/IXP46X network processors
If the I
2
C unit receives a general call address and the ICR General Call Disable bit is
set, the I
2
C unit ignores the general call address.
Software must ensure that the I
2
C unit is not busy before it asserts a reset. Software
must also ensure that the I
2
C bus is idle when the unit is enabled after reset. When
directed to reset, the I
2
C Bus Interface Unit will return to its default reset condition.
The CPU
is responsible for ensuring this occurs, not the I
2
C Bus Interface Unit
hardware.
When B=1, the sequence is a hardware general call and is not supported by the I
2
C
unit. Refer to the I
2
C-Bus Specification for information on hardware general calls.
I
2
C 10-bit addressing and CBUS compatibility are not supported.
21.6
Slave Mode Programming Examples
21.6.1
Initialize Unit
1. Write ISAR: Set slave address.
2. Write ICR: Enable all interrupts.
3. Set ICR[Unit Enable] bit to enable the I
2
C unit.
21.6.2
Write n Bytes as a Slave
1. When a Slave Address Detected interrupt occurs.
Figure 204. General Call Address
Table 281.
General Call Address Second Byte Definitions
Least
Significant Bit
of Second
Byte (B)
Second Byte
Value
Definition
0
06H
2-byte transaction where the second byte tells the slave to reset and
then store this value in the programmable part of their slave address.
0
04H
2-byte transaction where the second byte tells the slave to store this
value in the programmable part of their slave address. No reset.
0
00H
Not allowed as a second byte
NOTE: Other values are not fixed and must be ignored.
B4270-01
Ma ste r t o S la ve
S lave to Ma ster
STAR T
00 00 00 00
AC K
Da ta
Byt e
A C K
D ata
B yte
STOP
N B ytes + A C K
L east Sign ifican t Bit of M a ster Ad dress
AC K
Seco nd Byte
Seco nd Byte
0
A CK
First B yte
D e fines Tran sactio n