M38258MCM Datasheet, PDF (30/70 Pages) Mitsubishi Electric Semiconductor – SINGLE-CHIP 8-BIT CMOS MICROCOMPUTER

MITSUBISHI MICROCOMPUTERS
3825 Group
SINGLE-CHIP 8-BIT CMOS MICROCOMPUTER
LCD DRIVE CONTROL CIRCUIT
The 3825 group has the built-in Liquid Crystal Display (LCD) drive
control circuit consisting of the following.
• ^{LCD display RAM}
•^{Segment output enable register}
• ^{LCD mode register}
•^{Voltage multiplier}
• ^Selector
• ^{Timing controller}
• ^{Common driver}
• ^{Segment driver}
• ^{Bias control circuit}
A maximum of 40 segment output pins and 4 common output pins
can be used.
Up to 160 pixels can be controlled for LCD display. When the LCD
enable bit is set to “1” after data is set in the LCD mode register,
the segment output enable register and the LCD display RAM, the
LCD drive control circuit starts reading the display data automati-
cally, performs the bias control and the duty ratio control, and dis-
plays the data on the LCD panel.
Table 8. Maximum number of display pixels at each duty ratio
Duty ratio
Maximum number of display pixel
2
80 dots
or 8 segment LCD 10 digits
3
120 dots
or 8 segment LCD 15 digits
160 dots
4
or 8 segment LCD 20 digits
b7
b0
Segment output enable register
(SEG : address 003816)
Segment output enable bit 0
0 : Output ports P30–P35
1 : Segment output SEG18–SEG23
Segment output enable bit 1
0 : Output ports P36, P37
1 : Segment output SEG24,SEG25
Segment output enable bit 2
0 : Output ports P00–P05
1 : Segment output SEG26–SEG31
Segment output enable bit 3
0 : Output ports P06,P07
1 : Segment output SEG32,SEG33
Segment output enable bit 4
0 : Output port P10
1 : Segment output SEG34
Segment output enable bit 5
0 : Output ports P11–P15
1 : Segment output SEG35–SEG39
Not used (return “0” when read)
(Do not write “1” to this bit)
b7
b0
LCD mode register
(LM : address 003916)
Duty ratio selection bits
0 0 : Not used
0 1 : 2 duty (use COM0, COM1)
1 0 : 3 duty (use COM0–COM2)
1 1 : 4 duty (use COM0–COM3)
Bias control bit
0 : 1/3 bias
1 : 1/2 bias
LCD enable bit
0 : LCD OFF
1 : LCD ON
Voltage multiplier control bit
0 : Voltage multiplier disable
1 : Voltage multiplier enable
LCD circuit divider division ratio selection bits
0 0 : Clock input
0 1 : 2 division of Clock input
1 0 : 4 division of Clock input
1 1 : 8 division of Clock input
LCDCK count source selection bit (Note)
0 : f(XCIN)/32
1 : f(XIN)/8192 (f(XCIN)/8192 in low-speed mode)
Note : LCDCK is a clock for a LCD timing controller.
Fig. 28 Structure of segment output enable register and LCD mode register
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