2 Seven Segment Decoder

(5 points)

A seven segment decoder is typically used to determine which light emitting diodes in a seven segment

display should illuminate to display a digit specified in binary coded decimal.

Logisim includes such a seven segment display that you will use in this question.

The decoder takes as input four binary bits, which we label in order from most

significant bit to least significant bit, A3 A2 A1 A0. The decoder produces as

output a pattern of 7 bits, S6 S5 S4 S3 S2 S1 SO, which specifies which seg-

ments should illuminate. The figure on the right shows the relationship between

the pins and the corresponding segments of the display. Note that there is an

8th pin, S7, which controls the decimal point and that we will not use in this

assignment.

In this question, Instead of decoding BCD, your decoder should produce your

BID for binary bit patterns 0 through 8. (For example, if the input is 0, dis-

play the first digit of your ID. If the input is 1, diplay the second digit of your ID.)

You can produce any output (i.e., we don't care) for inputs of binary bit patterns

9 through 15. If your ID is 0123456789, your decoder should produce

exactly the patterns shown below. exactly the patterns shown below.

0323956389

SO S1 S2 S3

15

$4

S2

SO

S5

S3

S6

S7

S4 S5 S6 S7

1. Write out a truth table for your circuit and include this with your written answers.

2. Implement the 7 boolean functions in the provided logisim circuit file using only AND, OR and

NOT gates provided in the built in library (it is also OK to use NAND and NOR gates, and to negate

inputs on gates). You may use any solution you wish, but you may find it easiest to use a sum of

products approach, much like a PLA.

Create your solution in the provided circuit file, as it already has a set of inputs and outputs defined. These

input and output pins should not be moved so as to prevent the sub-circuit appearance from changing

(right-most tool bar button in logisim) as this is important for testing.