Expansion Bus Host Port Operation
8-22
8.5
Expansion Bus Host Port Operation
The expansion bus host port has two modes, which enable interfaces to exter-
nal processors, PCI bridge chips, or other external peripherals. These are the
synchronous host port mode and the asynchronous host port mode. The syn-
chronous host port mode can interface with minimum glue to PCI bridge chips
and many common microprocessors. The asynchronous host port mode en-
ables interfacing to genuine asynchronous devices.
The expansion bus host port block diagram is shown is Figure 8–13.
Figure 8–13. Expansion Bus Host Port Interface Block Diagram
XCS
XCNTL
XBOFF
XBLAST
XW/R
XAS
XRDY
XBE[3:0]
XD[31:0]
XHOLDA
XHOLD
’C6202
block
Control
arbitration
Bus
MUX
(XBGC, XBHC)
registers
control
host port
Expansion bus
bus
peripheral
controller
memory
Data
latches
address
XBEA
XBD data
latches
latches
address
XBISA
channel
auxiliary
DMA
Enhanced
XWAIT
Using pull-up/down resistors on the data bus during reset sets the host port
operational mode, the DSP bootmode, and endianness.