Stepper Motor Control

## 12. Web Page Remote Control Curtain In the construction of smart school, Internet of Things is gradually changing the traditional management model. Here we do a practical project of web page remote control curtain to explore the application of Internet of Things in school life. Through this project, you will not only be able to create a “compliant” curtain, but also master the core logic of the IoT system - “perception - decision - execution”, opening a window for the innovation of smart school. #### Principle **Mobile browser → WiFi → ESP32 → Control the motor to rotate 2 turns → curtain open/close** 1. **Mobile/Computer** Open the web page (enter the IP address of ESP32) 2. **Click the button** (forward/reverse) 3. **ESP32 receives instructions** (via WiFi) 4. **Motor rotation** (Rotate 2 turns, the curtain moves a corresponding distance) 5. **Curtain movement** (The motor drives the curtain through gears) #### Code Flow ```mermaid flowchart TD A[Users visit web page] --> B[Browser loads HTML] B --> C{User operation} C -->|Click forward button| D[send /forward request] C -->|Click reversal button| E[send /reverse request] D --> F[Forward rotate 2 turns] E --> G[Reverse rotate 2 turns] F --> H[Return empty response 200] G --> H H --> I[Browser receives response] I --> J[The motor finishes rotation] ``` #### Test Code ```c++ #include #include #include // motor parameters（28BYJ-48） const int STEPS_PER_REV = 2038; // actual step/turn const int MOTOR_PIN1 = 14; // IN1 const int MOTOR_PIN2 = 27; // IN2 const int MOTOR_PIN3 = 16; // IN3 const int MOTOR_PIN4 = 17; // IN4 // fixed parameters const int motorSpeed = 10; // fixed rotational speed 10 RPM const int rotationCount = 2; // fixedly rotate for 2 turns // WiFi credential const char* ssid = "YourWiFiSSID"; const char* password = "YourWiFiPassword"; // Initialize the stepper motor (note the pin sequence: IN1-IN3-IN2-IN4) Stepper myStepper(STEPS_PER_REV, MOTOR_PIN1, MOTOR_PIN3, MOTOR_PIN2, MOTOR_PIN4); WebServer server(80); // create Web server at port 80 void setup() { Serial.begin(115200); // connect to WiFi WiFi.begin(ssid, password); Serial.print("Connecting to WiFi..."); while (WiFi.status() != WL_CONNECTED) { delay(500); Serial.print("."); } Serial.println(""); Serial.println("WiFi connected"); Serial.print("IP address: "); Serial.println(WiFi.localIP()); // set the router server.on("/", handleRoot); server.on("/forward", []() { rotateMotor(rotationCount, false); server.send(200, "text/plain", ""); }); server.on("/reverse", []() { rotateMotor(rotationCount, true); server.send(200, "text/plain", ""); }); server.begin(); Serial.println("HTTP server started"); } void loop() { server.handleClient(); } // motor rotation function void rotateMotor(int turns, bool reverse) { myStepper.setSpeed(motorSpeed); int steps = STEPS_PER_REV * turns * (reverse ? -1 : 1); myStepper.step(steps); } // web page interface void handleRoot() { String html = R"=====( Stepper Motor Control

Stepper Motor Control

Fixed setting: Speed 10 RPM, 2 turns each time

)====="; server.send(200, "text/html", html); } ``` #### Code Explanation **Here covers extracurricular knowledge of HTML, CSS, and JS, so we only provide a brief introduction.** **1. Basic settings** ```c++ #include // stepper motor control library #include // ESP32 WiFi function library #include // Web server library // Motor parameters（28BYJ-48） const int STEPS_PER_REV = 2038; // Actual steps per turn const int MOTOR_PIN1 = 14; // IN1 const int MOTOR_PIN2 = 27; // IN2 const int MOTOR_PIN3 = 16; // IN3 const int MOTOR_PIN4 = 17; // IN4 // default parameters int motorSpeed = 10; // The default rotation speed is 10 turns per minute int rotationCount = 2; // By default, it rotates 2 turns // set the WiFi name and password const char* ssid = "YourWiFiSSID"; // your WiFi name const char* password = "YourWiFiPassword"; // your WiFi password // Initialize the stepper motor (note the pin sequence: IN1-IN3-IN2-IN4) Stepper myStepper(STEPS_PER_REV, MOTOR_PIN1, MOTOR_PIN3, MOTOR_PIN2, MOTOR_PIN4); WebServer server(80); // Create a Web server on port 80 ``` - Introduce the necessary libraries, set the WiFi napassword, define the stepper motor pin, and initialize the Web server.
**2. Initialization (setup)** **Connect to the WiFi network** ```c++ WiFi.begin(ssid, password); Serial.print("Connecting to WiFi..."); while (WiFi.status() != WL_CONNECTED) { delay(500); Serial.print("."); } Serial.println(""); Serial.println("WiFi connected"); Serial.print("IP address: "); Serial.println(WiFi.localIP()); // Print the obtained IP address ``` **Start the Web server** ```c++ server.begin(); // Start the Web server Serial.println("HTTP server started"); ```
**3. Main loop (loop)** ```c++ void loop() { server.handleClient(); // Handle client requests } ``` - Continuously listen for HTTP requests from browsers and call the corresponding processing functions (such as `handleRoot` and `handleControl`).
**4. HTML web page content** ```c++ String html = R"=====( ... )====="; server.send(200, "text/html", html); // Send the complete HTML page ``` - The code of an HTML web page. The page includes forward and reversal control buttons and parameter information, and interacts with the ESP32 backend via JavaScript. #### Test Result Please adjust the curtain to the position shown below before uploading the code. ![1003](../../img/1003.png) ![1004](../../img/1004.png) 1. After uploading the code, open the serial monitor and set the baud rate to 115200. You can see the printed IP information: ![1102](../../img/1102.png) 2. Enter the IP address on the serial monitor into your mobile phone/computer browser and you will see a simple control page. Note: Make sure your mobile phone/computer and ESP32 are connected to the same WiFi. ![1203](../../img/1203.png) 3. Click “Forward” or “Reversal” button to control the rotation of the motor. #### FAQ 1. If nothing is printed on the serial monitor, please press the reset button on the board. ![RESET](../../img/RESET.png) 2. If the ESP32 has not been able to obtain an IP address, it is usually because the WiFi connection has failed. Solutions: - Make sure that the WiFi name and password in the code have been replaced with yours. - Make sure your WiFi network is 2.4GHz. ESP32 does not support 5GHz WiFi. 3. If there is no page when entering the IP address, - Make sure the IP address is entered correctly. - Check whether your mobile phone/computer is on the same network as the ESP32.