Electronics Design

Button and LED Toggle Code for Seeed XIAO RP2040 in Arduino IDE

Overview

This documentation provides a detailed explanation of a simple Arduino program that toggles three LEDs on and off using a button. The code is designed to run on the Seeed XIAO RP2040 microcontroller. When the button is pressed, all three LEDs change their state from ON to OFF or vice versa.

Components Required

1. Seeed XIAO RP2040
2. 3 LEDs
3. 3 Current-limiting resistors (220 ohms recommended)
4. 1 Push button
5. PCB and soldering tools

Pin Configuration

• Button: Connected to digital pin 4 (buttonPin).
• LED 1: Connected to digital pin 7 (ledPin1).
• LED 2: Connected to digital pin 8 (ledPin2).
• LED 3: Connected to digital pin 9 (ledPin3).

Circuit Diagram

Connect the components as shown in the following table:

The button should be connected between the digital pin 4 and ground. Each LED should be connected to its respective pin with a current-limiting resistor between the pin and the LED anode. The cathode of each LED should be connected to ground.

Soldering Instructions

1. Prepare the PCB: Place the Seeed XIAO RP2040, LEDs, resistors, and push button on the PCB according to the pin configuration table.

2. Solder the Components: Carefully solder each component to the PCB. Ensure that the connections are secure and that there are no short circuits.

3. Check Connections: Use a multimeter to verify that all connections are correctly made and that there are no shorts.

Code Explanation

1. Variable Definitions:

   • buttonPin: Pin number for the button.
   • ledPin1, ledPin2, ledPin3: Pin numbers for the LEDs.
   • buttonState: Current state of the button.
   • lastButtonState: Previous state of the button.

2. Setup Function:

   • Initializes LED pins as OUTPUT.
   • Initializes the button pin as INPUT.

3. Loop Function:

   • Reads the current state of the button.
   • Checks if the button was pressed (transition from HIGH to LOW).
   • Toggles the state of the LEDs when the button is pressed.
   • Updates the last button state.
   • Adds a delay to debounce the button and avoid multiple toggles on a single press.

Code

cpp
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// Define the pins for buttons and LEDs
const int buttonPin = 4;
const int ledPin1 = 7;
const int ledPin2 = 8;
const int ledPin3 = 9;

// Variables to store the state of buttons
int buttonState = 0;
int lastButtonState = 0;

void setup() {
  // Initialize the LED pins as outputs
  pinMode(ledPin1, OUTPUT);
  pinMode(ledPin2, OUTPUT);
  pinMode(ledPin3, OUTPUT);
  
  // Initialize the button pin as input
  pinMode(buttonPin, INPUT);
}

void loop() {
  // Read the state of the button
  buttonState = digitalRead(buttonPin);

  // Check if the button is pressed (active LOW)
  if (buttonState == LOW && lastButtonState == HIGH) {
    // Toggle the LEDs
    digitalWrite(ledPin1, !digitalRead(ledPin1)); // Toggle LED 1
    digitalWrite(ledPin2, !digitalRead(ledPin2)); // Toggle LED 2
    digitalWrite(ledPin3, !digitalRead(ledPin3)); // Toggle LED 3
  }

  // Save the current button state for the next loop iteration
  lastButtonState = buttonState;
  
  // Add a small delay to debounce the button
  delay(50);
}

Steps to Upload the Code

1. Install the Arduino IDE:

   • Download and install the Arduino IDE from the official Arduino website.

2. Add Seeed XIAO RP2040 Board:

   • Open the Arduino IDE.
   • Go to File > Preferences.
   • In the "Additional Board Manager URLs" field, add the following URL:

     ruby
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     https://github.com/earlephilhower/arduino-pico/releases/download/global/package_rp2040_index.json
     

   • Click OK.
   • Go to Tools > Board > Board Manager.
   • Search for "Raspberry Pi Pico" and install it.
   • After installation, go to Tools > Board and select Seeed XIAO RP2040.

3. Select the Board and Port:

   • Go to Tools > Board and select Seeed XIAO RP2040.
   • Go to Tools > Port and select the appropriate port for your XIAO RP2040.

4. Upload the Code:

   • Copy and paste the provided code into the Arduino IDE.
   • Click the Upload button to upload the code to the XIAO RP2040.

Usage

Once the code is uploaded, pressing the button will toggle the state of the three LEDs. Each press will switch the LEDs from their current state (ON/OFF) to the opposite state.

Troubleshooting

• Ensure all connections are secure.
• Verify that the correct board and port are selected in the Arduino IDE.
• Check the button and LED wiring for proper connections.
• Make sure the current-limiting resistors are in place to prevent damage to the LEDs.

This simple project provides a foundation for understanding basic input and output operations on the Seeed XIAO RP2040 and can be expanded for more complex applications.