Department of Computer
and
Mathematical Sciences
CS 3402
Digital Logic
Laboratory
6
Lab 6: BCD-to-Seven-Segment Display Controller
Objectives:
The goal for this lab is to use LogicWorksTM to design a circuit that maps a 4-bit BCD digit to
the signals that control a seven-segment display using a decoder.
Background:
The display element contains seven light-emitting diodes (LEDs). When the appropriate LED
control line is asserted, the associated LED segment lights. The seven segments are controlled
independently; there is no limit to the number of segments that could be illuminated at the same
time. There is a seven-segment display device in LogicWorksTM as shown in figure 1.
Figure 1: LogicWorksTM Seven-Segment Display
Figure1 illustrates the configuration of the pins associated with LED segments.
There are 7400 series decoders available in LogicWorksTM. The outputs from these decoders are
active low. We can either implement these decoders either with AND gates or NAND gates
depend upon the number of 0's (maxterms) or 1's (minterms).
Task: BCD-to-seven-segment display controller
Activity 1 Construct a truth table for a BCD-to-seven-segment display controller.
Activity 2 Use LogicWorksTM to construct the circuit diagrams from the truth table in Activity 1
using one decoder 74154 and hex keyboard without strobe as input. Then test your circuit and
demonstrate your working circuit to the instructor.
Activity 3 Turn in the circuit diagrams in Activity 2.