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Page 9
Vancouver Design Center
Interfacing to the Philips MIPS PR31500/PR31700 Processor S1D13505
Issue Date: 01/02/05 X23A-G-001-07
3 S1D13505 Host Bus Interface
The S1D13505 implements a 16-bit host bus interface specifically for interfacing to the
PR31500/PR31700 microprocessor.
The PR31500/PR31700 host bus interface is selected by the S1D13505 on the rising edge
of RESET#. After releasing reset, the bus interface signals assume their selected
configuration. For details on S1D13505 configuration, see Section 4.2, “S1D13505 Config-
uration” on page 12.
Note
At reset, the Host Interface Disable bit in the Miscellaneous Disable Register
(REG[1Bh] bit 7) is set to 1. This means that only REG[1Ah] (read-only) and
REG[1Bh] are accessible until a write to REG[1Bh] sets bit 7 to 0 making all regis-
ters accessible. When debugging a new hardware design, this can sometimes give the
appearance that the interface is not working, so it is important to remember to clear this
bit before proceeding with debugging.
3.1 PR31500/PR31700 Host Bus Interface Pin Mapping
The following table shows the function of each host bus interface signal.
Table 3-1: PR31500/PR31700 Host Bus Interface Pin Mapping
S1D13505 Pin Name Philips PR31500/PR31700
AB20 ALE
AB19 /CARDREG
AB18 /CARDIORD
AB17 /CARDIOWR
AB[16:13] V
DD
AB[12:0] A[12:0]
DB[15:8] D[23:16]
DB[7:0] D[31:24]
WE1# /CARDxCSH
M/R# V
DD
CS# V
DD
BUSCLK DCLKOUT
BS# V
DD
RD/WR# /CARDxCSL
RD# /RD
WE0# /WE
WAIT# /CARDxWAIT
RESET# RESET#