Arduino Nano ESP32 - Web Apps Web Digital Pins
Overview
This tutorial covers the DIYablesWebDigitalPinsPage class from the DIYables ESP32 WebApps Library. The page presents each registered pin as a button in the browser. Output pins can be toggled; input pins display their current state. Pin configuration is done entirely in the sketch — the browser reflects whatever mode the sketch defines.
What This Tutorial Covers
- Enabling individual pins as WEB_PIN_OUTPUT or WEB_PIN_INPUT
- Reading output state changes from the browser via a callback
- Supplying input pin values to the browser via a read callback
- Pushing state updates to connected browsers from the sketch
Hardware Preparation
Or you can buy the following kits:
| 1 | × | DIYables Sensor Kit (18 sensors/displays) |
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Additionally, some of these links are for products from our own brand, DIYables .
Steps
Follow these instructions step by step:
- If this is your first time using the Arduino Nano ESP32, refer to the tutorial on setting up the Arduino Nano ESP32 development environment.
- Connect the Arduino Nano ESP32 board to your computer using a USB cable.
- Launch the Arduino IDE on your computer.
- Select the appropriate board (e.g. Arduino Nano ESP32) and COM port.
- Navigate to the Libraries icon on the left bar of the Arduino IDE.
- Search "DIYables ESP32 WebApps", then find the DIYables ESP32 WebApps Library by DIYables
- Click Install button to install the library.
- Search for DIYables ESP32 WebApps created by DIYables and click the Install button.
1
void setup() {
- You will be asked for installing some other library dependencies
- Click Install All button to install all library dependencies.
- On Arduino IDE, Go to File Examples DIYables ESP32 WebApps WebDigitalPins example, or copy the above code and paste it to the editor of Arduino IDE
/*
* DIYables WebApp Library - Web Digital Pins Example
*
* This example demonstrates the Web Digital Pins feature with automatic command handling:
* - Control output pins 0-13 via web interface
* - Monitor input pins 0-13 in real-time
* - Individual pin ON/OFF control for outputs
* - Real-time pin status feedback for inputs
* - Bulk operations (All ON, All OFF, Toggle All) for outputs
*
* Hardware: ESP32 Boards
*
* Setup:
* 1. Update WiFi credentials below
* 2. Upload the sketch to your Arduino
* 3. Open Serial Monitor to see the IP address
* 4. Navigate to http://[IP_ADDRESS]/webdigitalpins
*/
#include <DIYables_ESP32_Platform.h>
#include <DIYablesWebApps.h>
// WiFi credentials - UPDATE THESE WITH YOUR NETWORK
const char WIFI_SSID[] = "YOUR_WIFI_SSID";
const char WIFI_PASSWORD[] = "YOUR_WIFI_PASSWORD";
// Create WebApp server and page instances using platform abstraction
ESP32ServerFactory serverFactory;
DIYablesWebAppServer webAppsServer(serverFactory, 80, 81);
DIYablesHomePage homePage;
DIYablesWebDigitalPinsPage webDigitalPinsPage;
// Array to store the state of each digital pin (0-13). Index corresponds to pin number.
int pinStates[16] = { 0 }; // Initialize all states to LOW (0)
void setup() {
Serial.begin(9600);
delay(1000);
Serial.println("DIYables ESP32 WebApp - Web Digital Pins Example");
// Add home and digital pins pages
webAppsServer.addApp(&homePage);
webAppsServer.addApp(&webDigitalPinsPage);
// Optional: Add 404 page for better user experience
webAppsServer.setNotFoundPage(DIYablesNotFoundPage());
// Pin Configuration Examples:
// Method 1: Enable specific pins individually for output control
webDigitalPinsPage.enablePin(0, WEB_PIN_OUTPUT); // Enable pin 0 (TX - use with caution)
webDigitalPinsPage.enablePin(1, WEB_PIN_OUTPUT); // Enable pin 1 (RX - use with caution)
webDigitalPinsPage.enablePin(2, WEB_PIN_OUTPUT);
webDigitalPinsPage.enablePin(3, WEB_PIN_OUTPUT);
webDigitalPinsPage.enablePin(4, WEB_PIN_OUTPUT);
//webDigitalPinsPage.enablePin(5, WEB_PIN_OUTPUT); // Comment/uncomment to disable/enable
//webDigitalPinsPage.enablePin(6, WEB_PIN_OUTPUT); // Comment/uncomment to disable/enable
webDigitalPinsPage.enablePin(13, WEB_PIN_OUTPUT); // Enable pin 13 (built-in LED)
// Method 2: Enable pins for input monitoring
webDigitalPinsPage.enablePin(8, WEB_PIN_INPUT);
webDigitalPinsPage.enablePin(9, WEB_PIN_INPUT);
//webDigitalPinsPage.enablePin(10, WEB_PIN_INPUT); // Comment/uncomment to disable/enable
//webDigitalPinsPage.enablePin(11, WEB_PIN_INPUT); // Comment/uncomment to disable/enable
// Method 3: Enable all pins at once (uncomment to use)
// for (int pin = 0; pin <= 13; pin++) {
// webDigitalPinsPage.enablePin(pin, WEB_PIN_OUTPUT); // or WEB_PIN_INPUT as needed
// }
// Method 4: Enable pins in a range using for loop (uncomment to use)
// for (int pin = 7; pin <= 11; pin++) {
// webDigitalPinsPage.enablePin(pin, WEB_PIN_OUTPUT); // or WEB_PIN_INPUT as needed
// }
// Initialize enabled pins
int outputPins[] = { 0, 1, 2, 3, 4, 13 }; // Note: Pins 0,1 are TX/RX - use with caution
for (int i = 0; i < 6; i++) {
int pin = outputPins[i];
pinMode(pin, OUTPUT);
digitalWrite(pin, LOW);
pinStates[pin] = LOW;
}
int inputPins[] = { 8, 9 };
for (int i = 0; i < 2; i++) {
int pin = inputPins[i];
pinMode(pin, INPUT); // Use INPUT_PULLUP if needed
pinStates[pin] = digitalRead(pin);
}
// Start the WebApp server
if (!webAppsServer.begin(WIFI_SSID, WIFI_PASSWORD)) {
while (1) {
Serial.println("Failed to start WebApp server!");
delay(1000);
}
}
// Return the current state to display on Web App
webDigitalPinsPage.onPinRead([](int pin) {
return pinStates[pin]; // Return the current state of the pin
// You can implement custom read logic here if needed
});
// Handle the control request from Web App (for output pins)
webDigitalPinsPage.onPinWrite([](int pin, int state) {
digitalWrite(pin, state);
pinStates[pin] = state;
// You can implement custom control logic here if needed
});
// Handle pin mode change requests (optional)
webDigitalPinsPage.onPinModeChange([](int pin, int mode) {
if (mode == WEB_PIN_OUTPUT) {
pinMode(pin, OUTPUT);
digitalWrite(pin, LOW);
pinStates[pin] = LOW;
} else if (mode == WEB_PIN_INPUT) {
pinMode(pin, INPUT); // or INPUT_PULLUP as needed
pinStates[pin] = digitalRead(pin);
}
// You can implement custom mode change logic here if needed
});
}
void loop() {
// Handle WebApp server communications
webAppsServer.loop();
// Monitor input pins for real-time updates
static unsigned long lastInputCheck = 0;
if (millis() - lastInputCheck > 100) { // Check every 100ms
lastInputCheck = millis();
// Check input pins for changes and send real-time updates
int inputPins[] = { 8, 9 };
for (int i = 0; i < 2; i++) {
int pin = inputPins[i];
int currentState = digitalRead(pin);
if (currentState != pinStates[pin]) {
pinStates[pin] = currentState;
// Send real-time update to web clients
webDigitalPinsPage.updatePinState(pin, currentState);
}
}
}
// Add your main application code here
delay(10);
}
- Update the WiFi credentials in the sketch:
const char WIFI_SSID[] = "YOUR_WIFI_NETWORK";
const char WIFI_PASSWORD[] = "YOUR_WIFI_PASSWORD";
- Click Upload button on Arduino IDE to upload code to Arduino Nano ESP32
- Open the Serial Monitor
- The Serial Monitor output should resemble the following:
8
Serial.println("Hello World!");
Message (Enter to send message to 'Arduino Nano ESP32' on 'COM15')
New Line
9600 baud
DIYables WebApp - Web Digital Pins Example
INFO: Added app /
INFO: Added app /web-digital-pins
DEBUG: Enabling pin 0 with mode OUTPUT
DEBUG: Enabling pin 1 with mode OUTPUT
DEBUG: Enabling pin 2 with mode OUTPUT
DEBUG: Enabling pin 3 with mode OUTPUT
DEBUG: Enabling pin 4 with mode OUTPUT
DEBUG: Enabling pin 13 with mode OUTPUT
DEBUG: Enabling pin 8 with mode INPUT
DEBUG: Enabling pin 9 with mode INPUT
DIYables WebApp Library
Platform: Arduino Nano ESP32
Network connected!
IP address: 192.168.0.2
HTTP server started on port 80
Configuring WebSocket server callbacks...
WebSocket server started on port 81
WebSocket URL: ws://192.168.0.2:81
WebSocket server started on port 81
==========================================
DIYables WebApp Ready!
==========================================
Web Interface: http://192.168.0.2
WebSocket: ws://192.168.0.2:81
Available Applications:
Home Page: http://192.168.0.2/
Digital Pins: http://192.168.0.2/web-digital-pins
==========================================
- If nothing appears, press the reset button on the board.
- Enter the IP address from the Serial Monitor into a browser on the same network.
- Example: http://192.168.0.2
- The home page displays a card for the digital pins application:
- Select the Digital Pins card to open the pin control page:
- The page is also accessible directly at http://192.168.0.2/web-digital-pins.
- Toggle output pins by clicking the corresponding buttons. Pin 13 (built-in LED) should respond immediately.
Pin Configuration Methods
Pins must be registered before webAppsServer.begin(). Three patterns are supported:
Enabling Individual Pins
webDigitalPinsPage.enablePin(2, WEB_PIN_OUTPUT); // Pin 2 as output
webDigitalPinsPage.enablePin(3, WEB_PIN_OUTPUT); // Pin 3 as output
webDigitalPinsPage.enablePin(4, WEB_PIN_INPUT); // Pin 4 as input
Enabling a Range of Output Pins
// Registers pins 2 through 13 as outputs
webDigitalPinsPage.enableOutputPins(2, 13);
Enabling All Pins
// Registers all pins 0-13 (use with care for pins 0 and 1 — UART)
webDigitalPinsPage.enableAllPins();
Callbacks
Write Callback (Output Pins)
Called when the browser toggles an output pin:
webDigitalPinsPage.onPinWrite([](int pin, int state) {
digitalWrite(pin, state);
Serial.println("Pin " + String(pin) + " set to " + String(state));
});
Read Callback (Input Pins)
Called when the browser requests an input pin's current state:
webDigitalPinsPage.onPinRead([](int pin) -> int {
return digitalRead(pin);
});
Pushing State from the Sketch
When an input changes state outside of a browser request, push the update manually:
void loop() {
webAppsServer.loop();
int currentState = digitalRead(buttonPin);
if (currentState != lastButtonState) {
lastButtonState = currentState;
webDigitalPinsPage.updatePinState(buttonPin, currentState);
}
}
Web Interface Controls
- Pin button: Click to toggle an output pin HIGH or LOW. Green indicates HIGH; red indicates LOW.
- All ON: Sets all registered output pins to HIGH.
- All OFF: Sets all registered output pins to LOW.
- Toggle All: Inverts the current state of all output pins.
Input pins display their current state without a toggle button — the browser refreshes them periodically via WebSocket.
Troubleshooting
Pin state does not change when clicked
- Verify onPinWrite callback is registered before webAppsServer.begin()
- Confirm the pin is registered with WEB_PIN_OUTPUT
- Check the Serial Monitor for incoming WebSocket messages
Input pin shows wrong state
- Confirm onPinRead callback is registered
- Add a pull-up or pull-down resistor to avoid floating inputs
- Check digitalRead() returns the expected value in the callback
Page not accessible
- Check the IP address printed in the Serial Monitor
- Make sure port 80 is open on the network
- Both the board and browser device must be on the same 2.4 GHz WiFi network