General Call Address Second Byte Definitions - Intel PXA255 Developer's Manual

2
The I C unit supports sending and receiving general call address transfers on the I
software sends a general call message from the I
2
the I C unit from responding as a slave. If the ICR[GCD] is not set, the I
indeterminate state.
2
If the I C unit acts as a slave and receives a general call address while the ICR[GCD] bit is clear, it:
•
Sets the ISR[GCAD] bit
•
Sets the ISR[SAD] bit
•
Interrupts the processor (if the interrupt is enabled)
2
If the I C unit receives a general call address and the ICR[GCD] bit is set, it ignores the general
call address.
Figure 9-14. General Call Address
START
Master to Slave
Table 9-7. General Call Address Second Byte Definitions
Least
Significant
Bit of Second
Byte (B)
0
0
0
NOTE: Other values are not fixed and must be ignored.
Software must ensure that the I
ensure that the I
unit, except for ISAR, returns to the default reset condition. ISAR is not affected by a reset.
When B=1, the sequence is a hardware general call and is not supported by the I
the The I
2
I C 10-bit addresses and CBUS compatibility are not supported.
Intel® PXA255 Processor Developer's Manual
00000000 ACK Second Byte
First Byte
Slave to Master
Second
Byte
Value
2-byte transaction in which the second byte tells the slave to reset and store this
0x06
value in the programmable part of its address.
2-byte transaction in which the second byte tells the slave to store this value in
0x04
the programmable part of its address. No reset.
0x00 Not allowed as a second byte
2
C unit is not busy before it asserts a reset. Software must also
2
C bus is idle when the unit is enabled after reset. When directed to reset, the I
2
C-Bus Specification for information on hardware general calls.
2
C unit, it must set the ICR[GCD] bit to prevent
Data
ACK
0
Byte
Second Byte
Least Significant Bit of Master Address
Defines Transaction
Definition
2
I C Bus Interface Unit
2
C bus. When
2
C bus enters an
Data
ACK ACK STOP
Byte
N Bytes + ACK
2
C unit. Refer to
2
C
9-17