Casio CTK-620L, Service Manual

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LCD DRIVER (LSI401: SED1278F0A)
The LCD driver can drive a dot matrix LCD having 40 segment and 15 common lines. The LSI contains 240
graphic symbols in the built-in character generator ROM, and stores 80 characters in the built-in display data
RAM. In accordance with command from the CPU, the LSI is capable of displaying up to 16 characters
simultaneously. The following table shows the pin functions of LSI 401.
Pin No. Terminal In/Out Function
1 ~ 22,
63 ~ 80
23 VSS — GND (0 V) source
Terminals for the built-in clock pulse generator.The external
resistor connected determines the oscillation requency.
LCD drive voltage input.
Those voltages are used for generating the stepped pulse of
the LCD drive signals.
31, 32 LP, XCLS — Not used
33 VDD In DVDD (+5 V) source
34, 35 FR, DO — Not used
Data/command determination terminal.
High: data, Low: command
37 R/W In Read/write terminal. High: read, Low: write
Chip enable signal.
High: enable, the writing is done at fall edge.
Low: disenable
39 ~ 42 DB0 ~ DB3 — Not used. Connected to GND (0 V)
43 ~ 46 DB4 ~ DB7 In/Out Data bus
47 ~ 53, COM1 ~ COM7
55 ~ 62 COM9 ~ COM16
54 COM8 — Not used
SEG1 ~ SEG40 Out Segment signal output
24, 25 OSC1, OSC2 In/Out
26 ~ 30 V1 ~ V5 In
36 RS In
Out Common signal/output
38 E In
Pin No. Terminal In/Out Function
34 CE1B In Chip enable signal input. Low active.
35 ~ 41, 43 EIO0 ~ EIO7 In/Out Data bus for the effect RAM
EA0 ~ EA14 Out Address bus for the effect RAM
45 ECEB Out Chip enable signal output for the effect RAM
49 EOEB Out Output enable signal for the effect RAM
50 VSS3 In Ground (0 V) source
60 BWEB Out Write enable signal output for the effect RAM
62, 66, 70, 74, 78 VSS2 In Ground source
63, 67, 71, 75, 79 VDD2 In +5 V source
64, 65 PA0, PA1 Out Button scan signal output
68, 69, 77 PA2, PA3, PA7 — Not used
72 PA4 Out Data/command signal for LCD driver
73 PA5 Out Read/write signal for LCD driver
76 PA6 Out Chip enable signal for LCD driver
42 , 44, 46 ~ 48,
51 ~ 59, 61