# how to generate carry in seven segment display

Discussion in 'The Projects Forum' started by maruf10, Mar 16, 2009.

1. ### maruf10 Thread Starter New Member

Jan 17, 2009
4
0

i have made an up down counter which counts from 0 to 15.I have a binary output.now how can i show this output in 2 seven segment display?the main problem is to generate a carry 1 and when the counter counts from 10 to 15 and make that 0 when it counts from 9 to 0 and show that in a seven segment display.how can i solve this problem?

2. ### beenthere Retired Moderator

Apr 20, 2004
15,808
295
Your counter is binary and 7 segment displays can only show 0 - 9. You might find it easier to use BCD counters instead. If you wish to stay with the binary counter, you will need external logic to decode the binary count so your 7 segment drivers can handle the inputs. In essence, this will be the same as making two BCD counter outputs.

3. ### maruf10 Thread Starter New Member

Jan 17, 2009
4
0
i have used two 7447 bcd to seven segment display decoder for 2 display where the 4 binary (0000-1111) are the same for two decoders.is it wrong?how can i produce a carry when the counter counts from 1010(10) to 1111(15) and make it 0 for other case ... ... ... ?

4. ### SgtWookie Expert

Jul 17, 2007
22,201
1,809
You need a 74185 6-bit Binary to BCD converter. Unfortunately, they have been discontinued many years ago.

If you would like to emulate the functionality of that IC, then implement the following logic:
a. Examine the three most significant bits. If the sum is greater than four, add three and shift left one bit.
b. Examine each BCD decade. If the sum is greater than four, add three and shift left one bit.
c. Repeat step b until the least significant binary bit is in the least significant BCD location.

It would be a good deal easier to use BCD counters, which are readily available.