Epson S1D13705 - Manual (Page 467)

Epson Research and Development Page 15
Vancouver Design Center
Interfacing to the Motorola MPC821 Microprocessor S1D13705
Issue Date: 01/02/13 X27A-G-010-02
4 MPC821 to S1D13705 Interface
4.1 Hardware Description
The interface between the S1D13705 and the MPC821 requires minimal glue logic. One
inverter is required to change the polarity of the WAIT# signal (an active low signal) to
insert wait states in the bus cycle. The MPC821 Transfer Acknowledge signal (TA) is an
active low signal which ends the current bus cycle. The inverter is enabled using CS# so
that TA is not driven by the S1D13705 during non-S1D13705 bus cycles. A single resistor
is used to speed up the rise time of the WAIT# (TA) signal when terminating the bus cycle.
BS# (bus start) is not used in this implementation and should be tied low (connected to
GND).
The following diagram shows a typical implementation of the MPC821 to S1D13705
interface.
Figure 4-1: Typical Implementation of MPC821 to S1D13705 Interface
MPC821 S1D13705
A[15:31]
D[0:15]
CS4
TA
WE0
WE1
OE
SYSCLK
AB[16:0]
DB[15:0]
CS#
WAIT#
WE1#
WE0#
RD/WR#
RD#
BUSCLK
RESET#
Vcc
470
BS#
System RESET
Note:
When connecting the S1D13705 RESET# pin, the system designer should be aware of all
conditions that may reset the S1D13705 (e.g. CPU reset can be asserted during wake-up
from power-down modes, or during debug states).