5digitled

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.