This project was started in , electronics and control loops. Because I always need a cool project to learn new things, it was clear that something that can fly had to be built.
The project started as a "tricopter-only" project, but as I wanted to build smaller vehicles with more payload capacity, I decided to make some quadrotor, hexacopter and Y6 hexacopter firmwares too. My main interest is to build very small MAVs that fly as good as larger ones (or even better) and that can be controlled by wireless video link. I also experimented with autonomous flight in GPS-denied areas (video), and with GPS assisted autonomous hover (video).
-- William

Contact: Shrediquette @ g m x . d e --- All content published under CC Attribution-Noncommercial-Share Alike 3.0 Germany

I2C -> PWM converters

I2C to PWM converters will make it possible to use standard ESCs with my tricopter design (and other multicopters) without modifying anything. Each converter has it's own I2C address and will deliver one PWM signal for one ESC. The refresh rate will be selectable via solder jumpers (50 to 400 Hz). The final PCB for the converters will have a size of about 20x20mm (0.8x0.8'').
After some setbacks while trying to build a converter with a tiny45, I finally decided to take an ATmega8 (TQFP) instead. This controller features a 16bit timer and I know how to talk to it via I2C...

I put the circuit on a breadboard (with larger electronic components...) and it already works with a servo. I am optimistic that it will also work with ESCs and in flight. I'll try to make the PCB soon...


  1. That's good news!! William.
    I modified 3 tp 18A ESC, but only 1 is working with my quadcopter. why others are not working? it's weired.
    but I think I2C to PWM converter solve this problem.

  2. Dear William
    My name Oguz from Turkey.
    First thank you for your sharing your tricopter.I order every parts and i start to building shrediquette .Your documentation is perfect.Only i afraid will not able to modified escs.I guess
    I2C esc more fast but hard to modified.Your I2C to PWM converter will be perfect.
    Thank you again

  3. Ciao william
    Grazie per il tuo impegno sono impaziente
    di vedere finalmente un convertitore IC2 to PWM
    50 to 400 HZ molto interessante.
    dalla svizzera lugano

  4. Hi William, Are you utilizing the 3ch PWM so you can control three different esc from one chip? or is this circuit for a single ESC?

  5. Hi,
    no, I am generating only one PWM signal per controller. Therefore, one needs three of these converters for building a tricopter. In my opinion this is the most versatile and simple solution. I just ordered a bunch of these converter PCBs and I hope they'll work.....

  6. Hi William,
    One converter for each controller is an optimal solution.
    Your work is fantastic and you are truly competent in many subjects.

    Danilo from Italy