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Arduino Mega 2560 Controlled Railway Crossing with Servo Barriers and Audio Alerts

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Circuit Documentation

Summary

The circuit in question appears to be a complex system involving an Arduino Mega 2560 microcontroller as the central processing unit. It interfaces with various components including servos, a DFPlayer Mini MP3 module, a loudspeaker, a real-time clock (RTC DS3231), a 3.5" TFT LCD Shield, and several pushbuttons and LEDs for user interaction and feedback. The circuit is likely designed for a model railway crossing with light signals and barrier control, featuring sound playback capabilities and a display for user interface or status information.

Component List

Microcontroller

  • Arduino Mega 2560: A microcontroller board based on the ATmega2560, featuring a large number of IO pins, which is used as the central controller for the circuit.

Audio Components

  • DFPlayer Mini: A small and low-cost MP3 module that can directly play MP3 files stored on a microSD card.
  • Loudspeaker: An audio output device connected to the DFPlayer Mini for sound playback.

Display

  • 3.5" TFT LCD Shield (320 x 480): A color graphic LCD display for user interface and status display.

Sensors and Actuators

  • Servo: A motor capable of precise position control, used for moving barriers or other mechanical parts.
  • RTC DS3231: A real-time clock module for keeping track of the current time and date.

Power Supply

  • 4 x AAA Battery Mount: A battery holder for four AAA batteries, providing power to the circuit.
  • 3xAA Battery: A battery holder for three AA batteries, likely providing power to the DFPlayer Mini.

User Interface

  • Pushbutton: A simple switch that allows user interaction with the circuit.
  • Überwachungssignal (Monitoring Signal): Likely an LED or similar visual indicator for monitoring the status of the circuit.

Miscellaneous

  • Resistor: A passive component used to limit current or divide voltages in the circuit.
  • Octocoupler: An electronic device that transfers electrical signals between two isolated circuits by using light.
  • Lichtzeichenanlage (Light Signaling System): Likely a set of LEDs or lamps used to simulate railway crossing lights.

Wiring Details

Arduino Mega 2560

  • Connected to various components including servos, DFPlayer Mini, RTC DS3231, TFT LCD Shield, pushbuttons, and LEDs through its numerous IO pins.
  • Ground (GND) and power (5V, 3.3V) pins are used to power connected components and establish a common ground reference.
  • Digital pins are used for controlling servos, reading pushbutton states, and signaling LEDs.
  • Communication pins (TX, RX, SCL, SDA) are used for interfacing with the DFPlayer Mini and RTC DS3231.

DFPlayer Mini

  • Powered by 3xAA batteries.
  • Connected to the loudspeaker for audio output.
  • Interfaced with the Arduino Mega 2560 for control signals.

Servos

  • Powered by the 4 x AAA Battery Mount.
  • Controlled by specific PWM-capable digital pins on the Arduino Mega 2560.

RTC DS3231

  • Powered by the 5V output from the Arduino Mega 2560.
  • Uses I2C communication with the Arduino (SCL, SDA pins).

3.5" TFT LCD Shield

  • Mounted directly on the Arduino Mega 2560.
  • Uses digital pins for control and display data.

Pushbuttons and LEDs

  • Connected to digital pins on the Arduino Mega 2560.
  • Use resistors for current limiting and pull-up/pull-down configurations.

Resistor

  • Used in various parts of the circuit for current limiting and voltage division.

Octocoupler

  • Used for isolating different parts of the circuit and transferring signals without direct electrical connection.

Documented Code

The code provided is for the Arduino Mega 2560 microcontroller and is written in C++ using the Arduino IDE. It includes libraries for controlling the servo motors (Servo.h), interfacing with the TFT LCD (MCUFRIEND_kbv.h, Adafruit_GFX.h), managing the real-time clock (RTClib.h), and controlling the DFPlayer Mini (DFRobotDFPlayerMini.h). The code is structured to manage a model railway crossing with light signals and barrier control, featuring sound playback capabilities and a display for user interaction or status information.

The code is organized into several functions and states to handle the railway crossing logic, including signal light control, barrier movement, and sound playback. It also includes functions for displaying messages on the TFT LCD and handling button presses.

The main loop (void loop()) cycles through different states of the railway crossing, such as detecting an approaching train, securing the crossing by activating lights and barriers, and eventually reopening the crossing once the train has passed. The code uses a state machine approach with enumerated types (Status0 and Status1) to manage the crossing's status and transitions between states.

The setup function (void setup()) initializes the hardware components, sets pin modes, and establishes communication with the DFPlayer Mini and RTC. It also sets the initial state of the crossing and displays a startup message on the LCD.

The code includes error handling for component initialization, such as checking if the RTC is found and if the DFPlayer Mini is successfully initialized. If any component fails to initialize, the system continues to operate with limited functionality (e.g., without sound).

Throughout the code, there are informative comments and serial print statements to aid in debugging and provide real-time feedback on the system's status.

Note: The actual code is not included in this document due to its length, but it is summarized to provide an understanding of its functionality and structure.