How to Create a 4-bit Shift Register

Last modified by Microchip on 2025/01/27 10:01

Overview

A shift register is a sequential circuit that stores and shifts data through a series of flip-flops, synchronized by a clock. With some simple modifications, shift registers can support features like parallel loading, data hold, zeroing, and more. This makes it useful for storage, transfer, or conversion. This tips-n-tricks showcases a 4-bit shift register, a basic example that can be scaled as needed.

Configurable Logic Block (CLB) 4-bit Shift Register Schematic

Information

Note: The pic16f131_counter module generates the initial sequence for the shift register. If implementing your own design, ensure to provide a suitable initial sequence tailored to your application's requirements.

Requirements

Procedure

Implement the CLB Logic

Configure the CLB to implement flip-flops, OR gates, or equivalent logic for the rising edge detector.

Information

Note: If using MPLAB® Code Configurator, use the CLB Synthesizer tool or download the pre-configured CLB file.

Back to Top


Assign Pins

Connect the input of the shift register to the data source you wish to shift and route the outputs of the shift register to their respective destinations based on your application's requirements.

Back to Top


Verify the Design

Use a debugging tool to confirm the shift register is shifting data correctly and the outputs are functioning as intended.

Back to Top

Results

The results demonstrate the proper operation of the 4-bit shift register. The input signal (D4) is sequentially propagated through the outputs (D0 to D3) with each clock cycle, as expected. Each output reflects the shifted state of the input, confirming the shift register accurately shifts data across its stages.

4-bit Shift Register Waveforms

Learn More

Back to Top