# 4 Bit Bcd Input To 7 Segments Displays?

Discussion in 'The Projects Forum' started by thanosgen, Jan 15, 2007.

1. ### thanosgen Thread Starter Member

Jan 15, 2007
11
0
Be drawn and materialise in rasters a reasonable circuit that would appear in 7 seagments displays sectors the digits of hex system of numeration. the numbers that i want to see will be appearred as in the following form:

6 A B C D E F

Code the digits it will be given as BCD with Dip-switch

CAN HELP ME ΟR IS DIFFICULT?????

p.m. with multiplexter can i do it??????

i need something like this

i give the 1111 and i want to see the F etc

2. ### beenthere Retired Moderator

Apr 20, 2004
15,815
283
Hi,

Can't be done - BCD stands for Binary-Coded Decimal. It is only meant to represent the values 0 to 9. Four bits will give the values of 0 to f, but a 7 segment display can only show 0 to 9, plus meaningless junk. Your illustration shows a 7 segment display.

You will need an alphanumeric display plus additional circuitry to display the values of 0 to f.

3. ### hgmjr Moderator

Jan 28, 2005
9,030
214
Beenthere is 100% correct. 4-bit BCD is only capable of representing the digits 0 through 9.

On the other hand, if you have a 4-bit binary value, you can use a microcontroller to produce a set of characters using a 7-segment display that comes close to the 5 additional characters you would require.

1010 A (uppercase A)
1011 b (lowercase B)
1100 c (lowercase C)
1101 d (lowercase D)
1110 E (uppercase E)
1111 F (uppercase F)

hgmjr

4. ### thanosgen Thread Starter Member

Jan 15, 2007
11
0
how i do it?you have any circut or microcontroller?

Jun 30, 2006
833
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6. ### thanosgen Thread Starter Member

Jan 15, 2007
11
0
thanks my friend but this circuit have very much gates.i need something to put in raster.from 1 to 3 chips.

7. ### hgmjr Moderator

Jan 28, 2005
9,030
214
When you use the term "raster", do you perhaps mean multiplex such that one set of 7-segment drive electronics is shared among several 7-segment displays?

hgmjr

Jan 15, 2007
11
0
9. ### hgmjr Moderator

Jan 28, 2005
9,030
214
So when you use the term "raster", are you referring to the type of prototyping board onto which you are mounting your chips?

hgmjr

10. ### beenthere Retired Moderator

Apr 20, 2004
15,815
283
Hi,

One of those happy accidents led me to discover the MC14489. It will drive up to 5 displays and cover the full range of hexidecimal characters. It needs more than a dip switch input, though. Just google mc14489 for a data sheet.

11. ### hgmjr Moderator

Jan 28, 2005
9,030
214
I think such accidents are termed "serendipitous".

hgmjr

12. ### thingmaker3 Retired Moderator

May 16, 2005
5,072
6
What is needed is not a BCD-to-seven-segment driver, but rather a Hex-to-seven-segment driver. The [SIZE=-1]MC14489 cited by Beenthere is one example. So too are the 4N54, the EDE707, and for more modern applications the MAX6950/MAX6951.
[/SIZE]

13. ### lightingman Senior Member

Apr 19, 2007
374
22
OH HERE I GO AGAIN !!!!Yes you can do it "with an EPROM and a ULN2003"... Something small can do it, like a 2732 (27C32). Have you the means to program one ??, if so I will give you the code.If not just P.M. me your details and I will program and send you one (with schematics)... Daniel.