How to Charlieplex RGB LEDs

[@hippynurd]

Ive considered wiring up LEDs on a board the way you have done there. Ive made many 4x4x4 LED Cubes (charlie cubes) wired this way, it uses 16 microcontroller pins. Ive recently built a demo board that shows how a spire of 4 RGB LEDs works without the microcontroller, just switches to simulate the tri-state logic.

[@jaishetty8586]

Have a Totem pole also known as a push-pull output current amplifier to overcome the dim LED issue. Use higher voltage, but lower duty cycle. like a camera flash. Does not load the MCU too.

[@anneharrison1849]

So you explain the possible number of pins you can use and the number of RGB LEDs you can drive, but not how you dealt with the common cathode problem mentioned in the first part (or any further wiring, but that would be complex).

[@HammesHacks]

In the PCB, electrons flow from a pin on the micro controller (Arduino Uno) through a resistor, to a red, green or blue LED, then to the common pin, and to another resistor (like in normal charlieplexing). Because the pins are all grouped together (in the RCGB package) I need to work with groups of them. I tried to represent this grouping in the graph where the rows are the cathodes (C) and the columns are the anodes (RGB). This might not work with all LEDs, because the voltage drops across different colors might be different, but it has worked with 2 different brands of RCGB leds on my PCB.

[@anneharrison1849]

@@HammesHacks Thanks for the response. I think that confirms I understood the graph/chart correctly. I may need to actually get some LEDs out and figure out the smallest circuit. For some reason I find deriving the layout of a circuit from words rather than a diagram very hard - though I don't exactly find a logical diagram to an actual circuit board trivial - though on that skill I can at least tell I'm getting better. A circuit diagram for the smallest set of LEDs possible might be useful, though I understand it's time consuming to draw it up and make a video.Thanks again.