Epson SED 1520 Series - Manual (Page 15)

SED1520 Series
2–6 EPSON
PIN DESCRIPTION
(1) Power Pins
Name Description
V DD Connected to the +5Vdc power. Common to the V CC MPU power pin.
V SS 0 Vdc pin connected to the system ground.
V 1 , V 2 , V 3 , V
4
, V
5
Multi-level power supplies for LCD driving. The voltage determined for each liquid
crystal cell is divided by resistance or it is converted in impedance by the op amp,
and supplied. These voltages must satisfy the following:
V
DD
≥
V
1
≥
V
2
≥
V
3
≥
V
4
≥
V
5
(2) System Bus Connection Pins
D7 to D0 Three-state I/O.
The 8-bit bidirectional data buses to be connected to the 8- or 16-bit standard MPU
data buses.
A0 Input.
Usually connected to the low-order bit of the MPU address bus and used to identify
the data or a command.
A0=0: D0 to D7 are display control data.
A0=1: D0 to D7 are display data.
RES Input.
When the RES signal goes the 68-series MPU is initialized, and when it
goes , the 80-series MPU is initialized. The system is reset during edge
sense of the RES signal. The interface type to the 68-series or 80-series MPU is
selected by the level input as follows:
High level: 68-series MPU interface
Low level: 80-series MPU interface
CS Input. Active low. Effective for an external clock operation model only.
An address bus signal is usually decoded by use of chip select signal, and it is
entered. If the system has a built-in oscillator, this is used as an input pin to the
oscillator amp and an Rf oscillator resistor is connected to it. In such case, the RD,
WR and E signals must be ORed with the CS signals and entered.
E (RD) • If the 68-series MPU is connected:
Input. Active high.
Used as an enable clock input of the 68-series MPU.
• If the 80-series MPU is connected:
Input. Active low.
The RD signal of the 80-series MPU is entered in this pin. When this signal is
kept low, the SED1520 data bus is in the output status.
R/W (WR) • If the 68-series MPU is connected:
Input.
Used as an input pin of read control signals (if R/W is high) or write control
signals (if low).
• If the 80-series MPU is connected:
Input. Active low.
The WR signal of the 80-series MPU is entered in this pin. A signal on the data
bus is fetched at the rising edge of WR signal.