4559 Datasheet, PDF (43/148 Pages) Renesas Technology Corp – SINGLE-CHIP 4-BIT CMOS MICROCOMPUTER

4559 Group
LCD FUNCTION
The 4559 Group has an LCD (Liquid Crystal Display) controller/
driver. When data are set in LCD RAM and timer LC, LCD
control registers (L1, L2, L3, C1, C2, C3), and timer control
registers (W3, W4), 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 32 segment signal output pins
can be used to drive the LCD. By using these pins, up to 128
pixels (when internal power, 1/4 duty and 1/3 bias are selected)
can be controlled to display. When using the external input, set
necessary pins with the LCD control register 2 and apply the
proper voltage to the pins .
The LCD power input pins (VLC3–VLC1) are also used as pins
SEG0–SEG2. When SEG0 is selected, the internal power (VDD)
is used for the LCD power.
(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.
• 1/2 duty, 1/2 bias
• 1/3 duty, 1/3 bias
• 1/4 duty, 1/3 bias
Table 18 Table 11 Duty and maximum number of
displayed pixels
Duty
1/2
1/3
1/4
Maximum number of displayed
pixels
64 pixels
96 pixels
128 pixels
Used COM pins
COM0, COM1 (Note)
COM0–COM2 (Note)
COM0–COM3
Note. Leave unused COM pins open.
Common
driver
VDD
L23 _L23
r
L13
r
L22
r
L13
r
L21
r
L13
r
L20
to
to
to
to
to
....
....
....
....
....
....
....
....
....
Bias control
L12 ^{LCD ON/OFF}
control
Segment
driver
Segment
driver
Segment
driver
Segment
driver
Segment
driver
Segment
driver
....
....
....
....
....
Selector Selector Selector Selector Selector Selector
Decoder
1/2, 1/3, 1/4
counter
LCD clock
(from timer LC)
L11 L10
Fig 43. LCD controller/driver
LCD RAM
Register A
Rev.1.04 Aug 23, 2007 Page 43 of 146
REJ03B0188-0104