Initiated Pci Memory Write Cycle; Initiated Memory Write Transaction; Initiated I/O Read Transaction - Intel IXP45X Developer's Manual

®
PCI Controller—Intel IXP45X and Intel
10.2.7.6

Initiated Memory Write Transaction

The following transaction is a PCI Memory Write Cycle initiated from the IXP45X/
IXP46X network processors. This diagram is to understand the inner workings of PCI
transfers and may not reflect actual operation of the PCI Controller implemented on the
IXP45X/IXP46X network processors. The transaction is initiated to address location
hexadecimal 0x00000014. The value of binary 00 in PCI_AD (1:0) indicates that this is
a linear-increment transfer type. A hexadecimal value of 0x7 written on the PCI_CBE_N
bus during the address phase signifies that this is a PCI Bus Memory Read Cycle. All
byte enables are asserted for the transaction.
Notice that on this transaction the PCI_DEVSEL_N signal timing is different. This signal-
timing differential is due to the fact that the PCI_DEVSEL_N signal must become active
within the first three clocks after the PCI_FRAME_N becoming active. This requirement
could be different for every device that is on the PCI Bus. There is also no relationship
to when PCI_TRDY_N becomes active other than the PCI_TRDY_N signal must not
become active prior to the PCI_DEVSEL_N signal becoming active.
Figure 85.

Initiated PCI Memory Write Cycle

PCI_CLK
INT_REQ_N
INT_GNT_N
PCI_FRAME_N
PCI_AD (31:0)
PCI_IDSEL
PCI_CBE_N
PCI_IRDY_N
PCI_TRDY_N
PCI_DEVSEL_N
10.2.7.7

Initiated I/O Read Transaction

The following transaction is a PCI I/O Read Cycle initiated from the IXP45X/IXP46X
network processors. This diagram is to understand the inner workings of PCI transfers
and may not reflect actual operation of the PCI Controller implemented on the IXP45X/
IXP46X network processors. The transaction is initiated to address location
hexadecimal 0x00000010.
A hexadecimal value of 0x2 written on the PCI_CBE_N bus during the address phase
signifies that this is a PCI Bus I/O Read Cycle.
August 2006
Order Number: 306262-004US
®
IXP46X Product Line of Network Processors
0x00000014 DATA
0x7 0x0
®
Intel IXP45X and Intel
®
IXP46X Product Line of Network Processors
Develepor's Manual
B4288-01
517