CHAPTER 4: PERIPHERAL CIRCUITS AND OPERATION (LCD Driver)

4.7 LCD Driver (COM0–COM16, SEG0–SEG39)

4.7.1 Configuration of LCD driver

The S1C63558 has 17 common terminals (COM0–COM16) and 40 segment terminals (SEG0–SEG39), so that it can drive a dot matrix type LCD with a maximum of 680 (40 ⋅ 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 Mask option

The COM8–COM16 terminals can be set as the SEG47–SEG40 terminals by mask option. In this case, only 1/8 drive duty can be selected, so a dot matrix type LCD with a maximum of 384 (48 ⋅ 8) dots can be driven. When 48 segments ⋅ 8 commons is selected, COM terminals change to SEG terminals as follows: COM16 → SEG40 COM15 → SEG41 COM14 → SEG42 COM13 → SEG43 COM12 → SEG44 COM11 → SEG45 COM10 → SEG46 COM9 → SEG47 COM8 → SEG47

This option is valid on the PRC board, however, the SEG47–SEG40 terminals are separately provided. Therefore, be aware that the COM8–COM16 terminals cannot be changed to the SEG47–SEG40.

4.7.3 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 4.7.3.1 shows the VC1, VC23, VC4 and VC5 voltage values and boost/reduce status.

Table 4.7.3.1 LCD drive voltage when generated internally

LCD drive voltage

Boost/reduce status

Voltage value [V]

VC1

VC2 ⋅

0.5

1.13

VC23

VC2 (standard)

2.25

VC4

VC2 ⋅

1.5

3.38

VC5

VC2 ⋅

2

4.50

 

 

 

 

Note: The LCD drive voltage can be adjusted by the software (see Section 4.7.6). Values in the table are typical values.

4.7.4 LCD display control (ON/OFF) and switching of duty

(1)Display ON/OFF control

The S1C63558 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).

S1C63558 TECHNICAL MANUAL

EPSON

49