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EPSON
S1C6F567 TECHNICAL MANUAL
CHAPTER 4: PERIPHERAL CIRCUITS AND OPERATION (LCD Driver)
4.7 LCD Driver (COM0–COM16, SEG0–SEG59)
4.7.1 Configuration of LCD driver
The S1C6F567 has 17 common terminals (COM0–COM16) and 60 segment terminals (SEG0–SEG59), so
that it can drive a dot matrix type LCD with a maximum of 1,020 (60
× 17) dots.
The driving method is 1/17 duty, 1/16 duty or 1/8 duty dynamic drive with four voltages (1/4 bias),
VC1, VC23, VC4 and VC5.
LCD display ON/OFF can be controlled by the software.
4.7.2 Power supply for LCD driving
VC1, VC23, VC4 and VC5 are the LCD (1/4 bias) drive voltages generated by the LCD system voltage
circuit. These four output voltages can only be supplied to the externally expanded LCD driver.
Turning the LCD system voltage circuit ON or OFF is controlled with the LPWR register. When LPWR is
set to "1", the LCD system voltage circuit outputs the LCD drive voltages VC1, VC23, VC4 and VC5 to the
LCD driver.
The LCD system voltage circuit generates VC23 with the voltage regulator incorporated in itself, and
generates three other voltages by boosting or reducing the voltage VC23. Table 4.7.2.1 shows the VC1,
VC23, VC4 and VC5 voltage values and boost/reduce status.
Table 4.7.2.1 LCD drive voltage when generated internally
LCD drive voltage
VC1 = 1/2
× VC23
VC23 = (standard)
VC4 = 3/2
× VC23
VC5 = 2
× VC23
VDD = 2.7 V to 5.5 V
1/2
× VC23
1.950 to 2.4 V
3/2
× VC23
2
× VC23
Note: The LCD drive voltage can be adjusted by the software (see Section 4.7.5). Values in the table are
typical values.
4.7.3 LCD display control (ON/OFF) and switching of duty
(1) Display ON/OFF control
The S1C6F567 incorporates the ALON and ALOFF registers to blink display. When "1" is written to
ALON, all the dots go ON, and when "1" is written to ALOFF, all the dots go OFF. At such a time, an
ON waveform or an OFF waveform is output from SEG terminals. When "0" is written to these
registers, normal display is performed. Furthermore, when "1" is written to both of the ALON and
ALOFF, ALON (all ON) has priority over the ALOFF (all OFF).
(2) Switching of drive duty
In the S1C6F567, the drive duty can be set to 1/17, 1/16 or 1/8 by the software. This setting is done
using the LDUTY1 and LDUTY0 registers as shown in Table 4.7.3.1.
Table 4.7.3.1 LCD drive duty setting
LDUTY1
1
0
LDUTY0
1
0
Drive duty
1/8
1/16
1/17
Common terminal used
COM0–COM7
COM0–COM15
COM0–COM16
Maximum segment number
480 (60
× 8)
960 (60
× 16)
1,020 (60
× 17)