0-9 Counter Using Logic Gates

The TEJM4U course, focusing on the principles of digital electronics and microcontrollers, culminates in a final project designed to integrate and apply the knowledge acquired throughout the term. This final project involves the design and implementation of a digital 0-9 counter using fundamental logic gates. The project serves as a practical demonstration of how basic digital components can be orchestrated to achieve a specific and useful function in the realm of electronics.

The primary objective of this project is to construct a reliable and accurate 0-9 counter utilizing fundamental logic gates such as AND, OR, NOT, NAND, NOR, XOR, and XNOR. By doing so, the project aims to solidify the understanding of combinational and sequential logic, binary number systems, and the practical application of digital circuit design principles. This counter will have practical applications in various digital systems, such as timers, clocks, and user interfaces where numerical displays are essential.

• Breadboard
• Resistors
• Various resistors (e.g., 220Ω, 330Ω) for current limiting and pull-up/down configurations.
• Wire Cutters and Strippers
• Jumper Wires

1. Logic Gates

• Integrated circuits (ICs) containing various logic gates, such as:
• 74LS00 (Quad 2-input NAND gate)
• 74LS02 (Quad 2-input NOR gate)
• 74LS04 (Hex Inverter)
• 74LS08 (Quad 2-input AND gate)
• 74LS32 (Quad 2-input OR gate)
• 74LS86 (Quad 2-input XOR gate)
• Seven-Segment Display
• A common anode or common cathode seven-segment display for outputting the numbers 0-9.
• Seven-Segment Driver Chip
• A driver IC for the seven-segment display, such as the 74LS47 (BCD to seven-segment decoder/driver).
• Binary Counter ICs
• ICs for counting in binary, such as the 74LS90 (Decade counter) or 74LS93 (4-bit binary counter).
• Capacitors
• Various capacitors (e.g., 10µF, 100µF) for use in the clock pulse generator circuit.
• Power Supply
• LEDs
• Switches and Buttons
• Multimeter
• A digital multimeter for measuring voltage, current, and resistance during testing and troubleshooting.

To begin, you need to understand the project's requirements, which involve designing a 0-9 counter. Start by reviewing the functionality and behavior of a typical counter circuit. Drawing a schematic diagram is crucial at this stage as it provides a visual representation of how all components will be interconnected, helping to identify the necessary connections and components required for the circuit.

Use a 555 timer IC to generate a consistent clock pulse necessary for driving the counter. Connect the 555 timer to the breadboard, adding the appropriate resistors and capacitors to set the desired frequency. Verify the clock pulse output using an LED or a multimeter to ensure it functions correctly before connecting it to the counter.

Place the binary counter IC, such as the 74LS90, on the breadboard. Connect it to the clock pulse generator's output to enable counting operations. Ensure the counter IC is correctly powered and grounded, as stable power connections are critical for reliable operation.

Position the necessary logic gate ICs (AND, OR, NOT, etc.) on the breadboard. Connect the outputs of the binary counter IC to the inputs of these logic gates according to the schematic. This step is essential for decoding the binary count into a form suitable for driving the seven-segment display.

Place the seven-segment display and its driver IC, such as the 74LS47, on the breadboard. Connect the outputs of the logic gate network to the driver IC inputs, and then connect the driver IC outputs to the seven-segment display. This setup translates the binary count into a human-readable numerical display.

Power on the circuit and observe the seven-segment display to ensure it correctly counts from 0 to 9. If the display does not function as expected, use a multimeter to check connections and voltages at various points in the circuit. Troubleshooting and making adjustments based on these checks are crucial for achieving correct operation.