Specifications

CIRCUIT IDEAS
CIRCUIT IDEAS
D
otmatrix display is suitable for
displaying alphanumeric charac-
ters and symbols. Dedicated
dotmatrix display driver ICs are available,
but these are costly and not easily avail-
able commercially. It would therefore be
wise to make your own dotmatrix display,
using easily available common ICs. One
speciality of the circuit design presented
here is that you can yourself decide the
size and shape of the characters. Further,
you can design it for any language.
The principle of displaying a charac-
ter is that, for each character, a corre-
sponding bit pattern is stored in an
EPROM. When we supply a particular bi-
nary number, corresponding to the input
hex digits shown in Table I, bitmap of the
character shown against that number gets
transferred to the dotmatrix display. For
example, for letter ā€˜Z’, you are required to
enter hex 23 (referred as page address),
i.e. 010 on address lines A9 through A7,
and 0011 on address lines A6 through A3.
Addresses A2 through A0 (location ad-
dresses) are supplied by oscillator-cum-
JUNOMON ABRAHAM
BINARY TO DOTMATRIX DISPLAY
DECODER/DRIVER
Fig. 1: Schematic diagram of binary to dotmatrix display decoder/driver
RUPANJANA
TABLE I
Displayed Hex Displayed Hex
character input character input
000 L 15
101 M 16
202 N 17
303 O 18
404 P 19
505 Q 1A
606 R 1B
707 S 1C
808 T 1D
909 U 1E
A0A V 1F
B0B W 20
C0C X 21
D0D Y 22
E0E Z 23
F0F + 24
G10 – 25
H11 Ć· 26
I12x 27
J13 = 28
K14
150