Seven segment displays are IC_s consisting of light emitting diodes (LED_s) . The seven segments are arranged as shown below. Digital clocks, counters, and other equipment use seven segment displays.
By lighting certain combinations of these seven segments (a through g), we can display any decimal character 0 through 9. For example, when segments a, b, and c are lit, the number 7 is displayed. Likewise, segments b and c will display the number 1.
A seven segment display operates in conjunction with another IC called seven segment decoder/ driver that contains the necessary logic to decode a 4-bit BCD code in order to drive the segments of the seven segment display IC.
a. Design a seven segment decoder/driver that will decode the 4-bit BCD code to the equivalent decimal characters 0 through 9. The unused combinations 1010. 1011, 1100, 1101. 1110. and 1111 can be considered as don’t cares. Derive the simplest Boolean expressions for each of the seven segments (a through g).
b. Show the seven segment displays when the inputs are the unused combinations 1010. 1011, 1100. 1101. 1110. and 1111.
c. Redesign the seven segment decoder/driver so that the unused combinations will produce the hexadecimal outputs A, b, C, d, E, and F corresponding to the inputs are 1010, 1011, 1100, 1101, 1110, and 1111 respectively. Lower case for the letters B and D are chosen so they will not look like 8 and 0.
