3. Processor Bus Interface
102
PowerSpan II User Manual
80A1010_MA001_09
Integrated Device Technology
www.idt.com
3.4.1.2
Address Translation
The address generated by the PB Master is dependent on the use of address translation in the source
target image (see
“PCI-1 Target Image x Control Register” on page 268
. When address translation is
enabled
—
TA_EN bit is set in the PCI target image
—
PowerSpan II produces the processor bus
address using three inputs:
•
the incoming address from the source bus
•
the block size of the target image
•
the translation offset
This does not apply to DMA transfers because the destination address is assumed to have the necessary
offset by design.
For more information, see
“DMA x Destination Address Register” on page 310
.
3.4.1.3
Transaction type
The transfer type parameter of a PB master transaction, PB_TT, is specified with the PCI target image
or DMA channel registers. The following registers control the parameter for write transactions:
•
WTT[4:0] field in the
“PCI-1 Target Image x Control Register” on page 268
•
WTT[4:0] field in the
“DMA x Attributes Register” on page 317
The following registers control the parameter for read transactions:
•
RTT[4:0] field in the
“PCI-1 Target Image x Control Register” on page 268
•
RTT[4:0] field in the
“DMA x Attributes Register” on page 317
The default transfer type generated by the PowerSpan II PB Interface master is shown in
3.4.1.4
Address Parity
Address parity generation is provided on each byte of the address bus. Address parity bit assignments
are defined in
Table 20: Default PowerSpan II PB Master Transfer Type
PB Master Transaction
PB_TT[0:4]
Processor Bus Command
Writes
00010
Write with flush
Reads
01010
Read
Table 21: PowerSpan II PB Address Parity Assignments
Address Bus
Address Parity
PB_A[0:7]
PB_AP[0]
PB_A[8:15]
PB_AP[1]