ESP32 Web-Based Touch Interface for Motorized Vehicle Control

Microcontrollers can display sensor data through a web interface accessible via Wi-Fi. The interface shows real-time readings of sensor values (resistance, calculated pressure/temperature). This allows monitoring without physical connections and enables remote debugging. The web page can include graphs and logs for historical data analysis.

Web interfaces can display real-time sensor data by refreshing the page (using F5 in browsers) to update the displayed values. The gyroscope sensor continuously generates new readings as the device moves, and these values are transmitted to the web server and displayed on the HTML page. This allows users to observe how sensor values change in response to physical movements of the device.

The MT12 can display the RC vehicle's battery voltage on the main screen. Users select the RX bat value from the telemetry page and place it on any desired screen position. The RQL signal strength can also be displayed. This allows users to monitor battery voltage and signal strength at a glance during operation.

This extensive section covers real-time data display mechanisms and telemetry systems. Students learn how the handler function continuously monitors incoming data and updates the web page without page reload. The section explains that HTML elements must have unique identification attributes to be targeted for updates. Students learn that multiple clients can connect simultaneously to the same websocket server, with each connection operating independently. The section introduces telemetry as the process of measuring and transmitting data from remote objects, commonly used in robotics to monitor battery levels, sensor readings, and environmental conditions in real-time. Students learn practical applications including monitoring robot status, tracking spacecraft performance, and creating dashboard displays. The section covers reading battery levels using potentiometers or voltage dividers and distance using ultrasonic sensors, and how to format multiple sensor readings by concatenating them into a single string with delimiters.

Sensor values can be displayed on web pages in multiple locations: as part of the page title (in the browser tab), within header elements (H1 tags), and as pre-filled values in input fields. This demonstrates how embedded systems can provide real-time data visualization through web interfaces, making sensor information accessible on phones and browsers.

Stepper motor control requires understanding driver pin functions: Enable activates the driver, MS1-MS3 configure microstepping (full, half, 1/4, 1/8, 1/16 steps), Reset and Sleep manage power, Step and Dir control movement commands and direction, VMOT accepts 8-35V motor voltage. Current control uses Vref calculated as motor current limit divided by 2.5 ohms. The PID control system maintains balance through three terms: Proportional provides immediate error response, Integral accumulates past errors to correct persistent biases, Derivative anticipates future changes and damps oscillations. The ESP32 uses FreeRTOS to run PID calculations on one core while the other handles motor control. Motor speed is controlled by pulse frequency, with direction determined by PID output sign.

This section covers the complete PID control algorithm implementation and motor command generation. The algorithm calculates three terms: proportional (P × error), integral (I × accumulated error × delta_time), and derivative (D × rate of error change). Time delta is calculated using micros() for high precision. The integral term accumulates error over time to eliminate steady-state error. The derivative term predicts future error based on current rate of change. The floating-point control signal is cast to an integer for PWM output (0-255 for 8-bit controllers). Negative values indicate counterclockwise rotation, positive values indicate clockwise rotation, and zero indicates no movement. The system limits PWM values to prevent motor stalling—when error exists but PWM would drop below 30, it is clamped to 30. Direction pins are set accordingly. When error reaches zero, the system enters standby mode by disabling the H-bridge to prevent residual current flow that could cause motor heating.

Implementing a self-balancing robot on ESP32 requires understanding the dual-core architecture. The code structure includes libraries, motor pin definitions, MPU6050 instance creation, PID variable declaration, and timing variables for 15ms control intervals. The PID object links input (current angle), output (motor speed/direction), and setpoint (0°). The PRD task handle specifies which core runs the PID loop—Core 0 in this implementation. The motor control function runs on Core 1 by default. The PID loop continuously reads MPU6050 data, applies smoothing to reduce noise, executes PID calculations through a library, maps outputs to motor directions, and prints diagnostics. This separation ensures real-time control without interruptions.

The PID (Proportional-Integral-Derivative) controller drives motors to achieve desired positions by calculating error between actual and demand positions. The proportional term provides immediate response, causing motors to slow as they approach targets to prevent overshoot. The derivative term adds damping to reduce oscillation. For simple applications, pure proportional control may suffice. The controller output drives motors in either direction based on error sign. Raw potentiometer data should be smoothed to prevent jittery responses. The system demonstrates smooth arm movement with proper acceleration and deceleration curves.

This video demonstrates how to control a motor step using ESP32 with a custom protocol where data pulses after a synchronization pulse control motor direction (one pulse for clockwise, two pulses for counterclockwise) and speed (two pulses increase speed, three pulses decrease speed), with the ESP32 sending signals directly to a PIC microcontroller that drives the motor through an L293D driver.

Signal loss fail safe stops the motor if control signals are lost. The microcontroller monitors PWM input continuously; if no valid signal is received for 50-100ms, all MOSFETs turn off. This prevents uncontrolled motor operation if the transmitter disconnects. A dead band (20-50ms) filters noise from joystick vibrations, preventing erratic motor behavior from small signal fluctuations. These safety features are essential for reliable robotics applications where signal disconnection is more common than battery failure.

The Watch Dog logic operates continuously: it constantly asks 'Is there WiFi?' If yes, it does nothing and continues sleeping. If no, it starts counting. When the counter reaches 10 minutes without internet, the Watch Dog 'barks and bites' by cutting power to the router, waiting 10 seconds for capacitors to discharge, and then restoring power. This creates a fully autonomous device that handles router issues without human intervention.

The Hughes Autoformers Power Watchdog is an EPO (Emergency Power Off) device that automatically cuts power to an RV when electrical parameters exceed safe limits, including over voltage, under voltage, or over amperage, thereby protecting the RV's electrical system from damage; the Wi-Fi-enabled version allows users to monitor real-time electrical parameters such as voltage, amps, frequency, and watts on both legs through a smartphone app, and can be installed in various locations including storage bays.

A failsafe mechanism is a safety feature programmed into the Arduino that automatically stops the motor when the control signal is lost or interrupted. The system continuously monitors for incoming signals from the receiver. If no signal is detected within a short time window, the Arduino immediately commands the motor to stop. This prevents the dangerous situation where a motor continues running after the control signal has been disconnected.

Wireless emergency stop buttons work by continuously transmitting a signal when not pressed. When pressed, they stop transmitting, disabling the machine. If the signal is lost due to interference or battery depletion, the machine also stops. This demonstrates that wireless connections can be fail-safe because signal loss (whether intentional or accidental) results in the safe state, separating safety from wireless connection reliability.

This video demonstrates how to implement a secure HTTPS server on ESP32 using ESP-IDF by simplifying Expressive's example code, incorporating OpenSSL-generated self-signed certificates and keys into the program, and showing how to test the server using web browsers and Postman, with the key difference being the integration of certificate and key files into the web server initialization process.

An ESP32 microcontroller can function as a web server to control connected devices (such as LEDs) over Wi-Fi by creating an access point network, allowing users to turn devices on/off through a web browser on smartphones or computers by sending HTTP requests to the ESP32's IP address.

WSS (WebSocket Secure) is the secure version of WebSockets, similar to HTTPS for HTTP. It uses TLS/SSL encryption to secure the communication channel. WSS is essential for applications requiring secure real-time communication, such as financial trading platforms, chat applications, or any application handling sensitive data. The handshake process is similar to HTTP but uses the WSS protocol.

This comprehensive tutorial covers building an SSL-encrypted web server with ESP32 for remote GPIO control. SSL provides encryption for web traffic, protecting data transmitted over the air. Three certificate types exist: self-signed (requires generating keys for server and CA), authority-signed (requires certificate request and authority signing), and imported certificates. The demonstration uses TLS 1.2 with a self-signed certificate. Hardware setup includes GPIO pins (5, 13, 18, 19) connected to LEDs and an IRF313 MOSFET for controlling 12V loads. The application architecture follows: NVS initialization for persistent storage, WiFi configuration, SSL/TLS handshake establishment, and HTTP request handling. Non-volatile storage maintains GPIO states across resets. The demonstration shows browser certificate exception handling for self-signed certificates and verifies NVS state persistence after power cycles.