Embedded Roulette Machine

An interactive roulette game with LED ring, token detection and SPI display, powered by Raspberry Pi Pico 2W.

info

Author: Andrei Oprişor
GitHub Project Link: https://github.com/UPB-PMRust-Students/proiect-andreioprisor.git

Description

A prototype of an electronic roulette: the player inserts a token, bets on red/black, the “roulette” with 24 LEDs “spins” and, if the correct color comes up, wins a token; if not, loses the token.

The device is equipped with an IR sensor for token detection, a TCRT5000 sensor to confirm token passage, a servo for dispensing the winning token, an SPI display for messages, and a WS2812B LED ring for the “spin” animation.

The brains of the device is a Raspberry Pi Pico 2W microcontroller, which manages all interactions between sensors, servo, LEDs and display.

Motivation

I chose this project to combine physical token detection with LED animations and SPI‐display messages, exploring integrations between sensors, motors and a graphical interface on a modern microcontroller (Pico W).

Architecture

The device is organized into four main blocks, interconnected by the Raspberry Pi Pico 2W:

• Token I/O

  • IR Break-beam Module → detects slot entry
  • TCRT5000 Reflective Sensor → confirms the token passed

• Game Logic & Control

  • Raspberry Pi Pico 2W → reads sensors, “spins” LEDs, decides the winner and dispenses the winning token

• User I/O

  • 2 × Buttons (Red / Black) + 1 × Start Button → bet inputs and game start
  • SPI 128×160 ST7735 Display → shows messages (“You won!”, “You lost!”, “Choose a color!”, “Insert token!”, etc.)

• Physical Output

  • 24 × WS2812B LEDs (ring) → “spin” animation
  • Servo SG90 → token dispensing mechanism

Game Flow Summary

1. Insert token → IR break-beam ⏩ TCRT5000 confirms
2. Select bet (Red/Black) + Start
3. LED “wheel” animation via LED Ring: cycling lights
4. Determine result (Red/Black) randomly
5. Display message on the SPI ST7735 display
6. If the player wins → dispenseTokens() via SG90
7. Reset for the next player

Block Scheme

Log

Week	Completed
Week 5 – 11 May	Documentation milestone and setup
Week 12 – 18 May
Week 19 – 25 May

Hardware

1. Raspberry Pi Pico 2W

   • Main microcontroller, handles SPI, GPIO, PWM, and Wi-Fi.

2. IR Break-beam Module

   • Detects the token passing through the slot (~3–4 mm).

3. TCRT5000 Reflective Sensor

   • Confirms the token’s passage vertically.

4. Servo SG90

   • Barrier mechanism for holding and releasing tokens.

5. 37 × WS2812B LEDs (ring)

   • Colorful “spin” animation.

6. SPI Display 128 × 160 ST7735

   • Shows status messages and results.

7. 3 × Buttons (Red, Black, Start)

   • Bet inputs and game start.

8. 5 V / 2 A Power Supply

   • Common power for Pico W, servo, and LEDs.

9. PCB / Plexiglass Enclosure / Wiring

   • Mechanical support and connections.

Schematics

Bill of Materials

Device	Usage	Price (RON)
Raspberry Pi Pico 2W	Microcontroller	40
IR Break-beam Module	Token entry detection	10
TCRT5000 Reflective Sensor Module	Token passage confirmation	10
Servo SG90 9 g	Token dispensing	12
WS2812B LED Ring (37 LEDs)	“Spin” animation ring	30
SPI 128×160 ST7735 Display Module	Game message display	35
Push Button (Red / Black / Start) ×3	Betting and START input	6
Power Supply 5 V / 2 A	Power	25
PCB + Enclosure + Wiring	Assembly and structure	20
Total		188

Software

Library / Driver	Description	Usage
Arduino-Pico	Core for RP2040	HAL for GPIO, SPI, PWM
FastLED	WS2812B LED control	“Spin” LED animation
Adafruit_ST7735	SPI driver for ST7735 display	Rendering game text and graphics
Adafruit_GFX	2D graphics abstraction	Font and primitive drawing on the display
Servo.h	Servo motor control	Precise-angle token dispensing
TinyUSB / LWIP	USB / TCP-IP stack (optional Wi-Fi)	OTA updates or remote monitoring

Links

1. ST7735 SPI Display – Adafruit
2. FastLED Library
3. WS2812B LED Ring 24
4. TCRT5000 Sensor Tutorial
5. IR Break-beam Module Guide