Philips S1D13505 3.2 PR31500/PR31700 Host Bus Interface Signals

Page 10 Epson Research and Development
Vancouver Design Center
S1D13505 Interfacing to the Philips MIPS PR31500/PR31700 Processor
X23A-G-001-07 Issue Date: 01/02/05
3.2 PR31500/PR31700 Host Bus Interface Signals
When the S1D13505 is configured to operate with the PR31500/PR31700, the host
interface requires the following signals:
•BUSCLK is a clock input required by the S1D13505 host bus interface. It is separate
from the input clock (CLKI) and should be driven by the PR31500/PR31700 bus clock
output DCLKOUT.
•Address input AB20 corresponds to the PR31500/PR31700 signal ALE (address latch
enable) whose falling edge indicates that the most significant bits of the address are
present on the multiplexed address bus (A B[12:0]).
•Address input AB19 should be connected to the PR31500/PR31700 signal /CARDREG.
This signal is active when either IO or configuration space of the PR31500/PR31700
PC Card slot is being accessed.
•Address input AB18 should be connected to the PR31500/PR31700 signal
/CARDIORD. Either AB18 or the RD# input must be asserted for a read operation to
take place.
•Address input AB17 should be connected to the PR31500/PR31700 signal
/CARDIOWR. Either AB17 or the WE0# input must be asserted for a write operation to
take place.
•Address inputs AB[16:13] and control inputs M/R#, CS# and BS# must be tied to VDD
as they are not used in this interface mode.
•Address inputs AB[12:0], and the data bus DB[15:0], connect directly to the
PR31500/PR31700 address and data bus, respectively. MD4 must be set to select the
proper endian mode on reset (see Section 4.2, “S1D13505 Configuration” on page 12).
Because of the PR31500/PR31700 data bus naming convention and endian mode,
S1D13505 DB[15:8] must be connected to PR31500/PR31700 D[23:16], and
S1D13505 DB[7:0] must be connected to PR31500/PR31700 D[31:24].
•Control inputs WE1# and RD/WR# should be connected to the PR31500/PR31700
signals /CARDxCSH and /CARDxCSL respectively for byte steering.
•Input RD# should be connected to the PR31500/PR31700 signal /RD. Either RD# or the
AB18 input (/CARDIORD) must be asserted for a read operation to take place.
•Input WE0# should be connected to the PR31500/PR31700 signal /WR. Either WE0# or
the AB17 input (/CARDIOWR) must be asserted for a write operation to take place.
•WAIT# is a signal output from the S1D13505 that indicates the host CPU must wait
until data is ready (read cycle) or accepted (write cycle) on the host bus. Since the host
CPU accesses to the S1D13505 may occur asynchronously to the display update, it is
possible that contention may occur in accessing the S1D13505 internal registers and/or
display buffer. The WAIT# line resolves these contentions by forcing the host to wait
until the resource arbitration is complete.