Enhance Your Digital Systems with a Hardware-Based Binary Decoder
Binary decoders are fundamental components in digital systems, enabling tasks such as memory address decoding, display driving, data routing, and much more. By implementing a binary decoder using a Configurable Logic Block (CLB), you can achieve efficient hardware-driven decoding with minimal CPU overhead.
In this post, we’ll explore the design and implementation of a 2-to-4 binary decoder using the CLB, providing a foundation for creating more complex decoders.
What is a Binary Decoder?
A binary decoder translates an n-bit input into one of 2^n active output lines. For example, a 2-to-4 decoder takes two binary inputs and activates one of four outputs based on the input combination.
Truth Table for a 2-to-4 Decoder:
| A | B | OUT 0 | OUT 1 | OUT 2 | OUT 3 |
|---|---|---|---|---|---|
| 0 | 0 | 1 | 0 | 0 | 0 |
| 0 | 1 | 0 | 1 | 0 | 0 |
| 1 | 0 | 0 | 0 | 1 | 0 |
| 1 | 1 | 0 | 0 | 0 | 1 |
Each output is driven by an AND gate configured for a specific input combination. The corresponding output goes high (1) only when the inputs match its condition. For example:
- OUT 0 is high when A = 0 and B = 0.
- OUT 1 is high when A = 0 and B = 1, and so on.
How It Works
The binary decoder is implemented using:
- Configurable Logic Block (CLB): Implements the logic for to decode the binary input into four distinct outputs.
- Boolean Logic Expressions: Each output is generated using AND gates that match the corresponding input states.
Boolean Expressions:
- OUT0 = A’B’ (Active when A = 0 and B = 0)
- OUT1 = A’B (Active when A = 0 and B = 1)
- OUT2 = AB’ (Active when A = 1 and B = 0)
- OUT3 = AB (Active when A = 1 and B = 1)
The CLB synthesizer tool can be used to configure these logic expressions, ensuring efficient hardware-driven decoding.
Implementation Overview
Hardware Requirements:
- Microcontroller with CLB Peripheral (e.g., PIC16F13145)
- Curiosity Nano Development Board
- CLB Synthesizer Tool for defining and configuring the Boolean logic expressions
- Oscilloscope or Debugging Tool for verification
Configuration Steps:
- Define Input and Output Conditions: Assign GPIO pins for the inputs (A, B) and outputs (OUT0–OUT3).
- Implement Boolean Expressions: Use CLB Synthesizer tool to configure the logic gates needed for the Boolean Expression for the 2-to-4 decoder outputs.
- Verify the Design: Use a debugging tool to confirm the outputs change correctly based on input combinations.
Testing and Results
By observing the output waveform, we can confirm the correct operation of the binary decoder. Only one output is active at any time, corresponding to the input combination, demonstrating proper functionality of the 2-to-4 binary decoder.
Applications of CLB-Based Binary Decoders:
- Memory address decoding
- Seven-segment display drivers
- Data routing and multiplexing
- Keyboard encoding
By leveraging CLB, this approach reduces software complexity and enhances system efficiency.
Learn More
Explore additional CLB applications and binary decoder implementations:
- Binary Decoder CLB File – Available in the “Learn More” section of this page.
- CLB Peripheral Page
- More CLB Examples
- Microchip TRY: Live CLB Demonstration
- How to Import External Libraries into Configurable Logic Block Synthesizer Tool
- How to Create a Module in the Configurable Logic Block (CLB) Synthesizer Tool