This display has 7 signals, each going to a different LED. These are labeled A-G in the diagram below:
The 7-segment display has a standard encoding scheme. For example, the binary digit 3 (0011) needs to set the following signals for each of the 7 segments: A=1, B=1, C=1, D=1, E=0, F=0, G=1
Here's a chart of all the encodings:
This module will be used (instantiated) in a larger, project-level module.
This module will take in a clock signal and a 4-bit binary number. Outputs will be 7 signals, one for each of the LEDs in the display.
Because the LEDs are lit up in different patterns for different input values (see the example above for how input 0011 lights up 5 LEDs and keeps 2 off), each and every pattern must be hard-coded in the description language (VHDL in this example).
The larger module will drive the 4-bit input to the lower-level module using a switch (button) that increments a counter:
