April 13, 2024

Digital European roulette wheel takes benefit of charlieplexing

Arduino GroupMarch seventeenth, 2023

Roulette is certainly one of the traditional on line casino video games, together with poker, blackjack, baccarat, and craps. There are two standard variations of roulette: American and European. The American model options an extra zero (inexperienced) pocket and the numbered pockets in a special association. Mirko Pavleski constructed a digital European roulette wheel and used charlieplexing to drive all 37 LEDs, speaker, and button with a single Arduino Nano.

Multiplexing is a typical method for driving a grid of LEDs and it really works by setting the rows and columns to both HIGH or LOW. An LED will solely activate if its row is HIGH and its column is LOW (or vice-versa, relying on the LED’s orientation). This implies a microcontroller can management various LEDs equal to the variety of column pins multiplied by the variety of row pins. An 8×8 grid (16 pins) can due to this fact comprise 64 LEDs.

Charlieplexing is extra sophisticated, however permits for a lot extra LEDs. That quantity is the same as the variety of pins (N) squared, minus the variety of pins (N). So with 16 pins, a microcontroller may management 240 LEDs (16^2 – 16). This works due to a pair of pins can management two LEDs (one for every stream path), and two pairs can management their two LEDs every plus one other pair. That extends, leading to a schematic that appears like a pyramid. Jeremy Cook dinner has an in-depth explanation of charlieplexing here if you wish to know extra.

Pavleski took benefit of charlieplexing to drive all of the LEDs on their Roulette wheel, which wants one LED for every pocket. They used an Arduino Nano, which has 22 I/O pins. As we are able to see from the formulation within the earlier paragraph, 37 LEDs require solely 7 I/O pins when charlieplexed. That left loads of pins out there for the button and the buzzer.

The sport operation is easy. When the participant pushes the “spin” button, the LEDs illuminate in sequence earlier than touchdown on a pseudo-random pocket—ideally the one the place the participant positioned their guess.

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