MicroLight
This project uses MicroPython on a PyBoard to control a dimmable LED controller for 12-24v lamps using PWM.
Operating Principles
Dimmable DC lamps use a driver chip to achieve a constant current through the LEDs. Dimming is achieved by driving the LEDs to full intensity with pulse-width modulated DC current at a frequency that makes the flicker imperceptible. Annoyingly the driver chip in some lamps has an unused enable input that remains inaccessible inside, because it is used only for current limiting. Consequently, similar circuitry has to be duplicated externally.
A PyBoard periodically adjusts the light levels in response to interrupt-driven inputs from two rotary encoders with push switches.
Conclusion
The PyBoard was not chosen for its cost, but rather because it is a reliable, expandable easy-to-use component for hobbyists. The design should easily adapt to other MicroPython hardware. Although at present the rotary encoder software supports only PyBoard and the ESP8266 and ESP32 implementations, this covers quite a range of microcontrollers.
While the example PyBoard code controls two channels, the main.py file is
simply adjusted to create any number of channels for which you have hardware support.
Each channel's tick method is then called in a timed loop to scan for input
changes and adjust the light level if necessary. The typical single LED lamp
draws less than 1A from a 12V supply, but the channel driver circuit above is capable
(with appropriate heat sinking) of handling loads up to 60A, allowng systems of
all sizes to be configured.