Lennard Electronics

Kiwi made, innovative electronics

5 Digit LED Display
This is a circuit I dreamed up, back in 2002.  It uses  five CD4094 SIPO chips to drive five 7 segment LED displays.
I use a similar version on the I2C bus, using the PCF8574 to drive each digit (along with a darlington array chip if the LEDs are big and require a higher voltage).
Circuit Diagram:

Pinouts
 Pin

Function
1  Strobe digit 2
2  Vdd (5Vdc)
3  Vss
4  N/C
5   Strobe digit 0
6   Strobe digit 4
7   Strobe digit 1
8  Clock
9   Strobe digit 3
10  Data

Talking to the Module

To display a character, you need to send a byte to the module, then strobe the digit you want that character displayed on.


Creating a Character

To display a character on any digit, a 8 bit code is sent to that digit. One bit for each segment.

The format of the byte is as follows:

1 BYTE

 Segment

 .

 G

 F

 E

 D

 C

 B

 A

 Bit

 8

 7

 6

 5

 4

 3

 2

 1

For example, to display "8." send 11111111 to the display (255 decimal, FF hexadecimal).

To display "8" send 01111111 to the display (127 decimal, 7F hexadecimal).

The byte is sent to the module MSB first.

Character Map
 Character Binary Decimal Hex
 0 00111111  63  3F
1 00000110  6  06
2 01011011  91 5B
3 01001111 79 4F
4 01100110 102 66
5 01101101 109 6D
6 01111101 125 7D
7 00000111 7 07
8 01111111 127 7F
9 01101111 111 6F
A 01110111 119 77
b 01111100 124 7C
C 00111001 57 39
c 01011000 88 58
d 01011110 94 5E
E 01111001 121 79
F 01110001 113 71
G 00111101 61 3D
H 01110110 118 76
h 01110100 116 74
I 00110000 48 30
J 00001110 14 0E
 L 00111000 56 38
N 00110111 55 37
o 01011100 92 5C
P 01110011 115 73
R 00110001 49 31
t 01111000 120 78
U 00111110 62 3E
u 00011100 28 1C
Y 01101110 110 6E
Blank digit 00000000 0 00
Decimal
Point
1000000 128 80

Displaying a Character.

Once you have sent the byte to the module, you will need to strobe the digit/s you wish the character to be displayed on.

For example, to display a character on digit 0, pulse pin 5 high then low. To display the same character on digits 0 and 1, pulse both pins 5 and 7 high then low.


Software Samples.

The following samples are written in PBasic for the Parallax BS2.


Scrolling text:

A simple demonstration to show that almost anything is possible with the LENNARD Display Module, including a fancy effect as animated displaying of characters.

Here is the code.


CHARACTER - HEX ASCII converter

Use a terminal emulator to communicate with the Stamp Microcontroller. Set to 2400, 8, N, 1.

Here is the code.