# Connect 8 Bit adder to display result in 7 Segment Display in EWB

#### faraztahiri786

Joined Jan 16, 2022
5
Dear, I am making a 8 Bit Adder to display result in 7 Segment Display in Electronic Workbench, but when i get sum of 8 bit Sum(0-7) how I connect it to 7segment as 7 Segment display has just 7 lines to connect, I am sharing picture of circuit kindly tell me what should i do now.

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#### LesJones

Joined Jan 8, 2017
4,008
Even if you want to display only 4 bits (0 to F hex) you need to decode the 4 bits to give the required 7 bits to light the required segments of the 7 segment display. To display 8 bits you need two 7 segment displays with the decoding circuits. One possible decoder chip is the MC14495.

Les.

#### faraztahiri786

Joined Jan 16, 2022
5
to get 8 bits display I make this circuit and I want to add 128 ( 10000000) and 150(10010110) but now see the display in the circuit.

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#### Ian0

Joined Aug 7, 2020
7,531
to get 8 bits display I make this circuit and I want to add 128 ( 10000000) and 150(10010110) but now see the display in the circuit.
If you add 128 + 150, you get an overflow, because the answer is >256 so needs 9 bits

#### faraztahiri786

Joined Jan 16, 2022
5
Kindly understand circuit first. This time I take the number 64 on A & B. So I make A6,B6 On, therefore I want that 7segment display show 64 but it shows 40, kindly tell me now.

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#### LesJones

Joined Jan 8, 2017
4,008
You are adding 64 decimal (0x40) to 64. that is 128 decimal or 0x80 hexadecimal.
From your picture it looks like your 7 segment displays include the hexadecimal to 7 segment decoder.
It look like your simulator is accepting decimal input but is displaying it as hexadecimal.
I have never used simulators. I just design things and build them with the real components.

Les.

#### faraztahiri786

Joined Jan 16, 2022
5
could you please make 8 bit adder on electronic workbench and result will be displayed on 7segment

#### Papabravo

Joined Feb 24, 2006
20,169
So you seem unable to grasp the purpose of the binary to 7-segment decoder. It is a combinatorial function block with 4 inputs and seven outputs. For each of the 7 outputs there is a Boolean function that determines if a segment is on or off based on the 4 inputs.

#### BobTPH

Joined Jun 5, 2013
6,555
Are you trying to display hex or decimal? Decimal would be quite difficult.

Bob

#### faraztahiri786

Joined Jan 16, 2022
5
I am taking input in binary and want to show result in 7 segment display (Decimal)

#### Ian0

Joined Aug 7, 2020
7,531
I am taking input in binary and want to show result in 7 segment display (Decimal)
First convert binary to BCD, the use a 4511 to connect the BCD to the 7-segment display.
Converting binary to BCD isn‘t easy, and the best way of doing it is to program a parallel EPROM with a look-up table.

You can do it with some more adders, but it gets mighty complicated. Take the top 4 bits, multiply by 6 and add to the result. Then check if the lower 4 bits are greater than 9 and, if so, add 6again.

#### dl324

Joined Mar 30, 2015
15,536
I am making a 8 Bit Adder to display result in 7 Segment Display in Electronic Workbench
Is this school work?