A common requirement is to be able to change a 4-bit input to a 7-segment output.
The conversion is normally done from BCD to 7 segment.
There are ICs to do this job, but if we wanted to solve the problem with the gates we have studied then we need to follow the circuit design steps.
|
• circuit
design steps |
|
– identify
inputs and outputs |
|
– identify
required components |
|
– check
solution with a truth table |
|
– evaluate
the circuit design |
What are the inputs?
If we have four bits, then there are 16 possible inputs.
|
A |
B |
C |
D |
|
0 |
0 |
0 |
0 |
|
0 |
0 |
0 |
1 |
|
0 |
0 |
1 |
0 |
|
0 |
0 |
1 |
1 |
|
0 |
1 |
0 |
0 |
|
0 |
1 |
0 |
1 |
|
0 |
1 |
1 |
0 |
|
0 |
1 |
1 |
1 |
|
1 |
0 |
0 |
0 |
|
1 |
0 |
0 |
1 |
|
1 |
0 |
1 |
0 |
|
1 |
0 |
1 |
1 |
|
1 |
1 |
0 |
0 |
|
1 |
1 |
0 |
1 |
|
1 |
1 |
1 |
0 |
|
1 |
1 |
1 |
1 |
What are the outputs?
Refer back to the notes on 7-segment display for more detail HERE
|
No |
a |
b |
c |
d |
e |
f |
g |
No |
a |
b |
c |
d |
e |
f |
g |
|
0 |
|
|
|
|
|
|
|
8 |
|
|
|
|
|
|
|
|
1 |
|
|
|
|
|
|
|
9 |
|
|
|
|
|
|
|
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2 |
|
|
|
|
|
|
|
A |
1 |
1 |
1 |
0 |
1 |
1 |
1 |
|
3 |
|
|
|
|
|
|
|
b |
|
|
|
|
|
|
|
|
4 |
0 |
1 |
1 |
0 |
0 |
1 |
1 |
C |
|
|
|
|
|
|
|
|
5 |
|
|
|
|
|
|
|
d |
|
|
|
|
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|
6 |
|
|
|
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E |
|
|
|
|
|
|
|
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7 |
|
|
|
|
|
|
|
F |
|
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|