![]() ![]() This project here is similar but a bit more involved. It controls RGB LEDs so it can not only change the brightness but also the color of the light. Instead of a simple pot it used a pair of rotary encoders with push buttons. One controls the brightness, pushing its button turns the light on or off. The other changes the color, pushing its button toggles between color and white. There’s also a I2C interface included this time. I originally had the idea to hook this thing up to a Raspberry Pi and so be able to control the light from my computer or cell phone. ![]() I did establish an I2C connection to the RPi and it all works but it’s now installed as a stand-alone solution. Since we’re now controlling RGB LEDs we obviously need three independant PWM outputs, one for each for red, green and blue. But let’s go through the circuit step by step. The board is powered from a fairly powerful 12V supply that is always on. A LM2931 turns this into a microcontroller-friendly 5V. But if we want to connect this board to a Raspberry Pi we need to match the RPi’s 3.3 volts operating voltage. Apart from hobbyist projects there aren’t many microcontroller circuits running at 5V nowadays. Most of the PIC16Fxxx family of chips still handle 5 volts but this is becomming more and more of an exception. So in order to be compatible with the rest of the world this board will need a way to adapt it’s voltage.
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