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Intel
®
IXP45X and Intel
®
IXP46X Product Line of Network Processors
August 2006
Developer’s Manual
Order Number: 306262-004US
891
I2C Bus Interface Unit—Intel
®
IXP45X and Intel
®
IXP46X Product Line of Network Processors
21.5.7
General Call Address
A general call address is a transaction with a slave address of 00H. When a device
requires the data from a general call address, it acknowledges the transaction and
stays in slave-receiver mode. Otherwise, the device ignores the general call address.
The other bytes in a general call transaction are acknowledged by every device that
uses it on the bus. Devices that do not use these bytes must not send an Ack. The
meaning of a general call address is defined in the second byte sent by the master-
shows a general call address transaction. The least significant
bit (B) of the second byte defines the transaction.
shows the valid values and
definitions when B=0.
If the I
2
C acts as a slave and receives a general call address while the ICR General Call
Disable bit clears the I
2
C unit:
Figure 201. Master-Transmitter Write to Slave-Receiver
Figure 202. Master-Receiver Read to Slave-Transmitter
Figure 203. Master-Receiver Read to Slave-Transmitter, Repeated START,
Master-Transmitter Write to Slave-Receiver
B4265-01
Ma ste r t o S la ve
S lave to Ma ster
S TAR T
Slave Ad dr ess
R /W #
0
A CK
D ata
Byte
A CK
D ata
Byte
S TO P
N B ytes + A CK
W rite
A CK
First B yte
B4269-01
Ma ste r t o S la ve
Slave to M aste r
S TAR T
Slave Ad dr ess
R /W#
1
A CK
D ata
B yte
A CK
D ata
B yte
ST OP
N Byt es + A CK
R e ad
AC K#
De fa ult
Slave -R ece ive
M od e
First Byte
B4268-01
STA RT
S lav e
R/W#
1
ACK
Data
B y te A CK
Da ta
By te
N B ytes + A CK
Read
A CK
SR
Sl ave
R/W#
0
A CK
Data
B yte
ACK
Data
B yte
STO P
N By tes + A CK
Wr ite
ACK
A ddr ess
Addres s
M as ter to Slave
Slave to M as ter
Repeated
S TA RT
Data Chaining