# 4 Bit Bcd Input To 7 Segments Displays?

#### thanosgen

Joined Jan 15, 2007
11
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

#### beenthere

Joined Apr 20, 2004
15,819
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.

#### hgmjr

Joined Jan 28, 2005
9,029
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

#### thanosgen

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

#### thanosgen

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

#### hgmjr

Joined Jan 28, 2005
9,029
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

#### hgmjr

Joined Jan 28, 2005
9,029
So when you use the term "raster", are you referring to the type of prototyping board onto which you are mounting your chips?

hgmjr

#### beenthere

Joined Apr 20, 2004
15,819
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.

#### hgmjr

Joined Jan 28, 2005
9,029
I think such accidents are termed "serendipitous".

hgmjr

#### thingmaker3

Joined May 16, 2005
5,084
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]

#### lightingman

Joined Apr 19, 2007
374
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.