Specifications

9–4 EPSON
SED1278
PIN DESCRIPTION
MPU Interface
RS Register select signal input. Selects
between the data and instruction registers
during CPU access.
RS = 0: Instruction register access cycle
RS = 1: Data register access cycle
R/W This input selects between SED1278
register read and write cycles.
R/W = 0: Register write cycle
R/W = 1: Register read cycle
E Read/write execute signal input.
LCD Panel Interface
COM1 to COM16 Common driver outputs to the
LCD panel.
SEG1 to SEG40 Segment driver outputs to the LCD
panel.
OSC1 If the internal RC oscillator is used
to generate the LCD drive signals,
the feedback resistor, R
f, is
connected to this pin. If an external
clock source is used, the clock is
connected to this pin.
OSC2 If the internal RC oscillator is used
to generate the LCD drive signals,
the feedback resistor, R
f, is
connected to this pin. If an external
clock source is used, this pin is left
open.
DB0 to DB7 TTL level data input/output lines, for
connection to the system MPU data bus.
TABLE 1 The Function of the E Signal
RS
0
0
1
1
R/W
0
1
0
1
E
1
1
Instruction write cycle
DDRAM or CGRAM data write cycle
DDRAM or CGRAM data read cycle
Busy flag read cycle
Address counter read cycle
Operation
External Segment Driver Interface
LP Data latch pulse output for an external
X-driver.
XSCL Data shift clock output for an external
X-driver.
FR LCD AC-drive waveform for an external
X-driver.
DO Display data output for an external X-driver.