Specifications

EPSON 5–9
SED1225 Series
SED1225
Series
FUNCTION DESCRIPTION
MPU Interfaces
Interface type selection
The SED1225 can transfer data via the 4- or 8-bit data bus
or via the serial data input (SI). The parallel or serial data
input can be selected by setting the PS pin to high or low
(see Table 1).
The SED1225 has the C86 pin for MPU selection. If the
parallel input is selected (PS=high), if can be connected
directly to the 80-series or 68-series MPU by setting the
C86 pin to high or low (see Table 2). Also, the 8-bit or
4-bit data bus can be selected by the IF pin signal.
Serial interface
The serial interface consists of an 8-bit shift register and
a 3-bit counter. During chip select (XCS=low), an SI
input and an SCL input can be accepted. During no chip
select (XCS=high), the shift register and counter is
initialized (reset).
Serial data of D7 to D0 are fetched in this order from the
serial data input pin (SI) at the rising edge of serial clock.
The data is converted into 8-bit parallel data at the rising
edge of the eighth serial clock.
The serial data input (SI) is identified to have the display
data or command by the A0 input. It is display data if
A0=high, and it is command if A0=low.
Note: During continuous writing, the write time greater than the system cycle time (tcyc) must be set before the
subsequent write operation.
Interface to 4-bit MPU
If the 4-bit interface is selected (IF=low), the 8-bit
command and data, and its address are transferred in two
times.
The A0 input is fetched and identified at the rising edge
of “8 × n-th” serial clock (SCL). Figure 1 shows a serial
interface timing chart.
The SCL signals must be well protected from the far-end
reflection and ambient noise due to increased line length.
The operation checkout on the actual machine is
recommended.
Also, we recommend to repeat periodical command
writing and status refreshing to avoid a malfunction due
to noise.
XCS
XWR
D7 to D4 Upper (D7 to D4) Lower (D3 to D0)
Table 1
PS Type XCS A0 XWR SI SCL D0 to D7
H Parallel input XCS A0 XWR – – D0 to D7
L Serial input XCS A0 H, L SI SCL –
Table 2
C86 pin signal Type A0 XWR XCS D0 to D7
"L" 80 series A0 XWR XCS D0 to D7
"H" 68 series A0 E XCS D0 to D7