SM5L1/SM5L2/SM5L3
4-Bit Single Chip Microcomputers
LCD Function
DISPLAY SEGMENT
The SM5Lx contains a built-in circuit which directly
drive a 1/4 duty, 1/2 bias LCD. A sample LCD pattern
is shown in Figure 27.
A segment of the LCD can be turned on or off by set-
ting the corresponding bit in the display RAM (see Fig-
ure 14) to ‘1’ or ‘0’. The displayed segments can
assume any configuration containing up to a maximum
of 84/136/168 segments. An example of seven seg-
ment numeric display is shown in Figure 28.
H0
H1
H2
H3
SM5L1 S20 S19 S18 S17 S16 S15 . . . S2 S1 S0
SM5L2 S33 S32 S31 S30 S29 S28
SM5L3 S41 S40 S39 S38 S37 S36
5L1-27
Figure 27. LCD Pattern
H0
H1
H2
H3
LCD DRIVE WAVEFORMS
The LCD drive waveforms for the LCD pattern of
Figure 28 displaying a ‘5’ are shown in Figure 29 (the
segment output uses S0 and S1). For Figure 29, 3 V is
applied to the VDD pin, a 1.5 V is applied to the VM pin.
T
VDD (3 V)
H0
VM (1.5 V)
GND (0 V)
VDD (3 V)
H1
VM (1.5 V)
GND (0 V)
VDD (3 V)
H2
VM (1.5 V)
GND (0 V)
VDD (3 V)
H3
VM (1.5 V)
GND (0 V)
VDD (3 V)
S0
VM (1.5 V)
GND (0 V)
VDD (3 V)
S1
VM (1.5 V)
GND (0 V)
NOTE: Frame Frequency = 1/T = 64 Hz or 128 Hz
Frame frequency is selectable by mask option.
Figure 29. LCD Drive Waveforms
5L1-29
S0
S2
5L1-28
Figure 28. Sample LCD Pattern for
Seven Segment Numeric Display
22
Microcomputer Data Sheet