Building an 18F2550 Development Board

I have a few BEEPIC USB development board with 18F2550 lying around. I finally get around to put the realtime clock that I have build on prototype board into a proper PCB and case.

🧠 Why PIC18F2550?

The PIC18F2550 is a powerful 8-bit microcontroller from Microchip, featuring:

• USB 2.0 support for direct PC communication
• 32 KB Flash memory and 2 KB RAM
• Multiple I/O ports, including analog and digital pins
• Built-in timers, PWM, and interrupt capabilities

Its versatility makes it ideal for educational, industrial, and hobbyist applications.

🧩 Modular Design Philosophy

The beauty of this system lies in its modularity. Each peripheral—LEDs, relays, sensors, displays—can be added incrementally. This allows students and developers to build confidence, test subsystems, and scale complexity without overwhelming redesign.

Now it is time to make use of the board and turn it into a system building block that can be used for prototyping. This is mainly based on the pre-existing BOLT projects.

Step 1. Let’s gather all the components

• 1x BEEPIC development board
• 8x red LEDs
• 8x 1K resistors
• 1x 100K variable resistors
• 1x 16 pins female headers
• 1x 5 pins male headers

Step 2. Build the BEEPIC system

💡 LED Circuit Breakdown:

• PortB (RB0–RB7) is configured as digital output.
• Each pin drives an LED through a current-limiting resistor (1KΩ).
• LEDs provide visual feedback—ideal for debugging, status indication, or binary output display.

🔄 How It Works:

When a PortB pin is set HIGH (1), current flows through the resistor and LED, illuminating it. When set LOW (0), the LED turns off. This binary control allows you to represent sensor states, relay activation, or even ultrasonic distance thresholds.

Step 3. Load the test program

The program for the 18F2550 is written in C. You will need an MPLAB IDE to help with the development of the program that will be loaded into the BEEPIC system. You can download the latest MPLAB in the following location https://www.microchip.com/en-us/tools-resources/develop/mplab-x-ide

You can see how to load the program in the following video

Step 4. Further Development

Now that you have a working BEEPIC system, you can expand it with few additional components and starts experimenting. Some ideas that you can develop are:

1. Relay Control System

• Use transistors (e.g., BC337) to switch relays via microcontroller output.
• Ideal for automation: lights, motors, pumps.

2. Ultrasonic Measuring System

• Interface with HC-SR04 or similar sensors.
• Use Timer1 for echo pulse measurement.
• Display distance on LCD or transmit via USB.

3. LCD Display (16×2 or 20×4)

• Connect via 4-bit or 8-bit parallel mode.
• Display sensor readings, system status, or user prompts.

4. USB Communication

• Leverage the 18F2550’s built-in USB module.
• Send data to PC for logging, visualization, or control.
• Use Microchip’s USB stack or custom firmware.

I hope you enjoy this post and let me know if you have any questions.