M34551E8-XXXFP View Datasheet(PDF) - Renesas Electronics

Part Name

Description

Manufacturer

M34551E8-XXXFP

SINGLE-CHIP 4-BIT CMOS MICROCOMPUTER for INFRARED REMOTE CONTROL TRANSMITTER

Renesas Electronics 

MITSUBISHI MICROCOMPUTERS

4551 Group

SINGLE-CHIP 4-BIT CMOS MICROCOMPUTER for

INFRARED REMOTE CONTROL TRANSMITTER

LCD FUNCTION

The 4551 Group has an LCD (Liquid Crystal Display) controller/

driver. When proper voltage is applied to the LCD power supply

input pins and data are set in timer control registers (W2, W3),

timer LC, LCD control registers (L1, L2), and LCD RAM, the LCD

controller/driver automatically reads the display data and controls

the LCD display by setting duty and bias.

4 common signal output pins and 20 segment signal output pins

can be used to drive the LCD. By using these pins, up to 80

segments (when 1/4 duty and 1/3 bias are selected) can be

controlled to display. When the required number of segment pins

is 19 or less, pins SEG16–SEG19 (4) can be used as input ports

P20–P23.

(1) Duty and bias

There are 3 combinations of duty and bias for displaying data

on the LCD. Use bits 0 and 1 of LCD control register (L1) to

select the proper display method for the LCD panel being

used.

q 1/2 duty, 1/2 bias

q 1/3 duty, 1/3 bias

q 1/4 duty, 1/3 bias

Table 12 Duty and maximum number of displayed pixels

Duty Maximum number of displayed pixels Used COM pins

1/2 40 segments

COM0, COM1 (Note)

1/3 60 segments

COM0–COM2 (Note)

1/4 80 segments

COM0–COM3

Note: Leave unused COM pins open.

(2) LCD clock control

The LCD clock is determined by the timer 2 count source

selection bit (W23), timer LC control bit (W30), and timer LC.

Accordingly, the frequency (F) of the LCD clock is obtained

by the following formula. Numbers (Œ to ) shown below the

formula correspond to numbers in Figure 24, respectively.

q When using the prescaler output (ORCLK) as timer 2 count

source (W23=“1”)

1

1

1

F = ORCLK ! 16

!

!

LC + 1

2

Œ

Ž





q When using the f(XCIN) as timer 2 count source (W23=“0”)

1

1

1

F = f(XCIN) !

!

!

16

LC + 1

2

Œ

Ž





[LC: 0 to 15]

The frame frequency and frame period for each display

method can be obtained by the following formula:

F

Frame frequency =

(Hz)

n

Frame period = n (s)

F

F: LCD clock frequency

1/n: Duty

XCIN

ORCLK

Œ

W23

0

1



STCK

1/16

Ž

W31

1

0

(Note)

W30



0

Timer LC

1



1/2 LCD clock

Note: Count source is stopped by clearing to “0.”

Fig. 24 LCD clock control circuit structure

26

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