Portfolio Templates

These circuits can be used as portfolio circuits, as outlined in section 1.3.6 of the class syllabus.

Signed 3-bit Display

Maximum score: 10 points

Appropriate for: any checkpoint

Topic: general combinational logic and circuit optimization (does not count for decoders, MUX/DEMUX, or other categories)

This circuit displays the 3-bit 2’s complement value expressed on the DIP switch in decimal on a 7-segment display. A photograph of the circuit is shown below.

A photograph of a circuit soldered onto a protoboard. The 3-bit input on the DIP switch is 110, and the 7-segment display of the output indicates the value of -2.

Signed 2-bit Multiplier

Maximum score: 10 points

Appropriate for: any checkpoint

Topic: binary arithmetic (does not count for decoders, MUX/DEMUX, or other categories)

This circuit takes two 2-bit inputs A1A2 and B1B2 that are both 2’s complement values and multiplies them together. The output is formatted as a sign and magnitude value and displayed on two 7-segment displays. There is no overflow detection in this circuit, as all possible output values between negative 2 and positive 4 are capable of being displayed.

Photograph of the signed multiplication circuit as soldered on a protoboard.

LED Rainbow Circuit

Maximum score: 10 points

Appropriate for: checkpoints 2 or 3

Topic: general sequential logic

This circuit uses latches to turn on one of eight individual LEDs at the press of a button. Once the LED is turned on, pressing its button a subsequent time will not make any changes to its state. To reset (turn off) all of the LEDs, a reset button can be pressed. A video of this functionality is shown below.

Multiplexed Display

Maximum score: 20 points

Appropriate for: checkpoint 3 only

Topic: counters

This circuit uses four (common-cathode) 7-segment displays that are connected such that each of the same segment anodes are tied together, as shown below.

Schematic of two dual 7-segment displays with all four sets of anodes connected such that all a's are connected together, all b's are connected together, etc.

In this manner, each individual display is written to one at a time. First, display 1’s cathode is asserted, and whatever value is written to the BCD to 7-segment decoder is sent to the segment anode pins. Then, display 2’s cathode is asserted, and the value written to the BCD to 7-segment decoder is sent to the segment anode pins. Then, display 3, then, display 4.

If this process occurs on a fast enough timescale, it appears that each digit is continuously on. The video below demonstrates the operation of this circuit in real-time. Each of the four digits appears to be constantly lit up.

The video below is a slow-motion recording of the circuit. In this manner, you can see each of the individual digits being written to in sequence.