Epson LQ-2550 Technical Manual page 105

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Figure 2-55 shows the command/data write timing for the SED 1200.
The sub CPU selects which type of information will be written, command or data, using address line
AO (command: AO = O, data: AO = 1), then outputs 4-bit data on the data bus (DO to D3). The sub CPU
enables the outputs of tri-state LS375 (96) by changing port PB4 from high to low, and writes the
command/data into the SED 1200.
Table 2-36 lists the commands of the SED 1200, and Figure 2-56 shows the character code map for
nibble and lower nibble (4 bits X 2 = 8 bits).
SUB-CPU
(7 B)
( ' B "
out put
AO
o f IC (9B)
DO– D3
*: n=O Write command
Command
SET CURSOR
DIRECTION
CURSOR ADDRESS
–1 +1
CURSOR FONT
SELECT
CURSOR BLINK
ON/OFF
DISPLAY ON/OFF
CURSOR ON/OFF
SYSTEM RESET
LINE SELECT
St
LINE
CODE
SET CGRAM
ADDRESS
SET CGRAM DATA
:1: Refer to Figure
I
1
n = 1 Write data
Figure 2-55.
Table 2-36. SED1200 Corr
WR AO
0 0 0
0 0 0
0 0 0
0 0 0
0 0 0
0 0 0
0 0 0
0 0 0
0 0 0
0 0 0
0 0 1
0 0 0
0 0 0
56.
1
,
n *
I
First Input
0 0 0 0
0 0 0 0
0 0 0 0
0 0 0 0
0 0 0 0
0 0 0 0
0 0 0 1
0 0 0 1
1 0
(CHARACTER CODE)"'
0 0 1 0
0 1 0 0
2-59
Second Input
D / l
0 1 0
– 1/+ 1 DO= 1 :– 1
0 1 1
1 0 0 A/U
1 0 0 ON/OFF DO= 1 :ON
1 1 0 ON/OFF DO= 1 :ON
1 1 ON/OFF DO= 1 :ON
0 0 0 0
0 0 0 2/1
(N Colums-l)B
(N Colums-l)B
(Lower Address)
t
1
!
I
1
Function
DO= O:INC.
DO= O:+ 1
DO= 1 :Blinking
DO= O: Under Line
DO= O: OFF
DO= O: OFF
DO= O: OFF
DO= 1 :Display
for 1 line
DO= O: Display
for 2 lines
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