In the world of DIY electronics, the combination of creativity and hardware skills can lead to the development of fascinating and useful projects. One such project is creating a custom LED matrix display using the EPM7128SLC84-15 FPGA (Field Programmable Gate Array). The EPM7128SLC84-15 is a powerful, versatile FPGA chip that can be programmed to perform various tasks such as controlling LED displays, handling input signals, or processing real-time data. This project is focused on building a 5x5 custom LED matrix display that can show dynamic patterns or characters, providing a hands-on experience in both hardware and FPGA-based digital logic design.
Project Overview
In this project, we will design and implement a simple 5x5 LED matrix display controlled by the EPM7128SLC84-15 FPGA. The project will not require any programming or software code since the FPGA chip will be manually configured using its configuration pins and hardware wiring. The LED matrix will display different static or scrolling patterns, and users will interact with the system using switches to change patterns or reset the display.
This project is perfect for those who want to dive into FPGA-based projects without delving into code writing. It combines FPGA hardware skills with a fun and practical use case—a customizable LED display.
Materials Needed
To build this custom LED matrix display, you will need the following materials:
EPM7128SLC84-15 FPGA – The main chip used to control the LED matrix.
5x5 LED Matrix Display – This will be the display used to show patterns.
Resistors – Various resistors to limit current and protect the LEDs and FPGA.
Switches – For user input to change or reset patterns on the display.
Capacitors – For decoupling and stabilization of power supply signals.
Pushbuttons – For controlling the switching between patterns.
Power Supply – A 5V DC regulated supply to power the FPGA and LED matrix.
Connecting Wires – For connecting the FPGA to the LED matrix and switches.
Breadboard – For prototyping the circuit before soldering it to a PCB.
Soldering iron and basic tools – For assembling the circuit.
Clock oscillator (optional) – To generate timing signals for the FPGA.
Step 1: Understanding the EPM7128SLC84-15 FPGA
Before diving into the wiring and assembly, it’s important to understand how the EPM7128SLC84-15 FPGA functions. This chip is part of the MAX 7000 family of FPGAs, which are known for their high flexibility, low power consumption, and ability to implement complex digital circuits. The EPM7128SLC84-15 comes in an 84-pin package and has 128 macrocells, which can be programmed to perform a variety of logic functions.
Key features of the EPM7128SLC84-15 include:
● 128 macrocells for implementing digital logic.
● 84 programmable I/O pins, which can be configured to interact with external components like LEDs, switches, and other devices.
● On-chip resources like flip-flops, multiplexers, and logic gates, which are used to implement the desired functionality of the project.
For this LED matrix project, the FPGA will be used to generate control signals for each individual LED in the matrix, creating patterns or animations by switching LEDs on and off at the right time.
Step 2: Setting Up the 5x5 LED Matrix
A 5x5 LED matrix consists of 25 individual LEDs arranged in rows and columns. In a typical matrix configuration, each LED is connected to both a row and a column, allowing the FPGA to control which LEDs light up by applying voltage to the corresponding row and column pins.
For this project, the matrix is assumed to be a common cathode type, where the cathodes of all LEDs are connected to a common ground. This simplifies the control circuitry because the FPGA can simply set the row and column pins high or low to turn specific LEDs on or off.
The 5x5 LED matrix is connected to the FPGA as follows:
Rows (R1 to R5) – These are connected to five pins on the FPGA. Each row will correspond to one of the 5 horizontal lines of the matrix.
Columns (C1 to C5) – These are connected to five more pins on the FPGA. Each column will correspond to one of the 5 vertical lines of the matrix.
By selecting one row at a time and driving the appropriate columns high or low, the FPGA can light up any combination of LEDs in the matrix.
Step 3: Wiring the EPM7128SLC84-15 to the LED Matrix
Now it’s time to connect the EPM7128SLC84-15 FPGA to the 5x5 LED matrix. The wiring is relatively simple, as the FPGA only needs to drive the rows and columns of the LED matrix.
Row Pins – Connect five FPGA I/O pins (e.g., pins 1-5) to the row lines (R1 to R5) of the LED matrix.
Column Pins – Connect five more FPGA I/O pins (e.g., pins 6-10) to the column lines (C1 to C5) of the LED matrix.
In total, you’ll need 10 I/O pins to control the 5x5 matrix (5 for rows and 5 for columns). The remaining FPGA pins can be used for user input (e.g., pushbuttons) or optional control signals like clock inputs.
Once the LED matrix is wired to the FPGA, you can power up the circuit and begin controlling the LEDs using the FPGA’s I/O pins.
Step 4: User Interface for Pattern Selection
To make the project interactive, you can include a simple user interface to allow the user to change the displayed pattern on the LED matrix. This interface could consist of pushbuttons that the user can press to cycle through different predefined patterns or reset the display.
You will wire the pushbuttons to some of the unused FPGA I/O pins (e.g., pins 11-13). When the user presses a button, it will generate a signal that the FPGA can detect and use to select a different pattern for the LED matrix.
Pattern Select Button 1 – This button will cycle through a set of static patterns (e.g., a checkerboard, a single moving dot, etc.).
Pattern Select Button 2 – This button will switch the display to a scrolling pattern, where LEDs light up in sequence.
Reset Button – This button will clear the matrix and turn off all LEDs.
To ensure proper operation, debouncing circuits or software logic should be used, but in this case, as we're working without code, simple wiring with resistors to ground may suffice for reliable button presses.
Step 5: Powering the Circuit
The EPM7128SLC84-15 FPGA requires a stable 5V power supply. This can be provided by a regulated 5V DC adapter, which will also power the LED matrix. The 5V power supply is connected to both the VCC pin of the FPGA and the anodes of the LEDs in the matrix.
The ground (GND) pin of the FPGA will be connected to the common ground of the LED matrix, the pushbuttons, and the power supply.
Step 6: Testing the Display
Once everything is wired up, it’s time to test the system. Power on the circuit and press the buttons to see how the FPGA controls the LEDs. The display should show different patterns depending on which button the user presses. The FPGA will handle the switching of rows and columns to display the patterns correctly.
● Static Patterns – These could be simple geometric shapes like a cross or a square.
● Scrolling Patterns – You could simulate the effect of a moving dot across the matrix or create scrolling text (though this would require some advanced logic in the FPGA).
● Reset Function – The reset button should clear the matrix, turning all LEDs off.
Step 7: Troubleshooting
If the display is not working as expected, check the following:
Ensure that all connections to the FPGA’s I/O pins are correct.
Make sure the power supply is providing 5V and the ground is properly connected.
If the display is not updating, ensure that the switches are wired correctly and that the FPGA is receiving signals from them.
Double-check the LED matrix connections to ensure that the rows and columns are wired properly.
Conclusion
Building a custom LED matrix display with the EPM7128SLC84-15 FPGA is an exciting and educational DIY electronics project that allows you to dive into FPGA hardware design without the need for complex coding. By manually wiring the FPGA to control the rows and columns of a 5x5 LED matrix, you can create a variety of dynamic patterns and interactive features.
This project not only gives you a functional, customizable display but also provides a hands-on introduction to working with FPGAs, understanding digital logic, and interacting with hardware through pushbuttons. Whether you're a beginner or an experienced electronics enthusiast, this project offers a fun and practical way to learn more about digital design and FPGA-based systems.