USB RGB LED Controller

This is a feature-rich LED controller board with many convenient features. The USB interface allows for direct selection of operating modes on the PC screen, eliminating the need for additional input devices on the board. The project comes pre-programmed with several modes, including slow and fast color changes, and temperature-based colors (the color depends on the temperature measured from a temperature sensor (DS1821)). Other modes include constant colors that can be configured via a C# Windows application. In fact, there are even more possibilities, especially when using USB. Write your own application or use a PC application to represent CPU load or other content using RGB colors. The project is built around a PIC18F2550 microcontroller, which has a built-in USB interface. Therefore, the USB requires only a few components, allowing you to focus on other parts of the circuitry.

This project is a full-color LED controller that can be configured via USB connection. The color of the connected LEDs (common anode only) depends on the selected operating mode:

Slow color change (approximately 40 minutes)

Rapid color change (approximately 2 minutes)

Temperature-based color (temperature range adjustable)

Constant Color 1

Constant Color 2

Constant Color 3

Constant Color 4

In color-changing mode, the LEDs automatically cycle through all possible colors of the rainbow within a certain time period.

In temperature-based mode, the color changes according to the temperature measured by the DS1821 sensor. At home, I use this mode to light it up based on the temperature of the radiator.

In constant color mode, the LED color is constant, but it can be configured via USB using a C# Windows application.

Using this application, the circuit can also be used to light up LEDs, changing the color from blue to red, depending on the PC's CPU load or the screen content.

The following components are needed to build an RGB LED controller:

C1 220nF

C2 100nF

C3 10μF

C4 47μF

C5 22pF

C6 22pF

IC1 PIC18F2550_28DIP

IC2 7805

S1 button

PT1 PTC660

Q1 20MHz

T1 IRFZ34N

T2 IRFZ34N

T3 IRFZ34N

R1 4.7kΩ

R2 4.7kΩ

R3 4.7kΩ

R4 100kΩ

R5 100kΩ

R6 100kΩ

R7 22Ω

R8 22Ω

R9 180Ω

R10 180Ω

R11 180Ω

SV1 4-pin connector

SV2 3-pin connector

USB1 MINI-USB

X2 connector

Flexible 12V LED light strip, 13.5cm, RGB

First, a PCB needs to be created. The image above shows the PCB layout. The Eagle file is included in the project download.

Next, solder the 5V components required to power the microcontroller onto the PCB. Once completed, supply 12V and check that the microcontroller has 5V (pin 8 = GND, pin 20 = +5V). Then, you can solder the remaining components.

The diagram below shows how to connect the LED strip (common anode) and the wiring of the DS18S20.

Last but not least, the PIC needs to be programmed accordingly. This is done in three steps:

1. Insert the unprogrammed PIC18F2550 into your programmer of choice (I used a homemade SPRUT Brenner 8). Use this programmer to burn the USB bootloader (18f2550_boot_rb4.hex) into the PIC. The bootloader is provided with the project download. Configuration bits are included in the hex file.

2. Now insert the PIC into the circuit you just built and connect it to your PC via USB cable. Then, while holding down the mode button on the circuit, power on the circuit. This will put the PIC into boot loading mode. XP/Vista will request a driver. You provide the driver provided by the Microchip USB Framework installation (C:\Microchip Solutions\USB Device - MCHPUSB - Generic Driver DemoDriver and inf), and the device will be recognized and listed in the Device Manager.

3. Finally, the application firmware (RGBController.hex) can be programmed into the PIC using the PDFSUSB application provided by the Microchip USB Framework.

Now, you can interrupt the power to the circuit to reboot the PIC (this time without pressing the mode button), allowing the PIC to enter application mode. The connected LEDs should now light up. If Windows requests the driver again, please use the driver provided in my project download (located in the ConfigurationUIWinXP_USBDriver folder). Now press the mode button once to initialize the PIC (this only needs to be done once).

If you now launch the Windows application (ConfigurationUIRGBConfigurator inDebugRGBConfigurator.exe), you should be able to configure the PIC according to your needs, as shown in the first image above.

Please note:

To launch on Windows 7, please use this version of the software. It uses a newer version of the Microchip USB API DLL (mpusbapi.dll, version 2.6a) and is compiled with the correct options to work on 64-bit systems.