Reading Vespa Button

Introduction

Got your Vespa and want to know how to use it? Don't worry, we're here to help you with these first steps and to show how to use the basic functions of the library developed for it.

In this tutorial you will see how to read the built-in button on the Vespa and how it can be applied in practice.

List of Materials

Direct Activation

As a first basic example of using the button, this will make the Vespa's internal LED L turn on every time the button is pressed and turn off when the button is released.

Code

For this tutorial, we will not be using the Vespa library. However, follow the steps in the tutorial First Steps with the Vespa to learn how configure your IDE to program it.

Once done, upload the following code

/*******************************************************************************
* Vespa - First Steps for Button Reading (v1.0)
*
* Direct activation demo code by reading the Vespa button.
*
* Copyright 2022 RoboCore.
* Written by Giovanni de Castro (06/13/2022).
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version (<https://www.gnu.org/licenses/>).
*******************************************************************************/

// Declaration of the variable that stores the pin connected to the button
const int BUTTON_PIN = 35;

// Declaration of the variable that stores the pin connected to LED L
const int LED_PIN = 15;

void setup() {
  
   // Configure the pin connected to the button as an input with "pull-up"
   pinMode(BUTTON_PIN, INPUT_PULLUP);

   // Configures the pin connected to LED L as an output and with low initial logic level
   pinMode(LED_PIN, OUTPUT);
   digitalWrite(LED_PIN, LOW);
  
}

void loop() {

   // Declaration of the variable that stores the digital reading of the Vespa button
   int button_read = digitalRead(BUTTON_PIN);

   // Checks if the button was pressed (logic low level - "LOW")
   if(button_read == LOW){ // If the button was pressed
     digitalWrite(LED_PIN, HIGH); // Turn on LED L
   }
   else { // If not pressed
     digitalWrite(LED_PIN, LOW); // Turn off LED L
   }
  
}

Understanding the Code

In the global declarations at the beginning of the code, we only declarate the constants BUTTON_PIN and LED_PIN, which store the GPIO connected to the internal Vespa button and LED.

In the code configuration (function void setup()), we just configure the pin connected to the button as an input with the internal "pull-up" resistor activated (INPUT_PULLUP) and we configure the pin connected to the LED as an output of the board, initially with the initial low logic level ("LOW").

In the code loop (function void loop()), we have the declaration of the variable button_read that receives the digital reading of the pin connected to the button. Next, we check if the button was pressed by the if(button_read == LOW) condition. When the button is pressed with a "pull-up" resistor in its circuit, the logic level read is low ("LOW"). Taking this into account, when the button is pressed, the condition created is true and LED L is then turned on. Otherwise, if the button has not been pressed, the previously created if condition will be false, then the else condition will be true and LED L will be off.

What Must Happen

After uploading the code to the board, see that LED L will light up when the button is pressed and will turn off after releasing the button, as in the GIF below.

Final Result

Activation With Memory

In this second example, we will make the Vespa's LED L turn on and off when the button is pressed, maintaining its state until the button is pressed again.

Code

To do this, load the following code onto your Vespa.

/********************************************************************************
* Vespa - First Steps for Button Reading (v1.0)
*
* Activation demonstration code of latch activation of the Vespa button.
*
* Copyright 2022 RoboCore.
* Written by Giovanni de Castro (06/13/2022).
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version (<https://www.gnu.org/licenses/>).
*******************************************************************************/

// Declaration of the variable that stores the pin connected to the button
const int BUTTON_PIN = 35;

// Declaration of the variable that stores the pin connected to LED L
const int LED_PIN = 15;

// Declaration of the variable to control LED L
bool light = false;

void setup() {

   // Configure the pin connected to the button as an input with "pull-up"
   pinMode(BUTTON_PIN, INPUT_PULLUP);

   // Configure the pin connected to LED L as an output and with initial low level
   pinMode(LED_PIN, OUTPUT);
   digitalWrite(LED_PIN, LOW);
  
}

void loop() {
  
   // Check if the Wasp button was pressed
   if (digitalRead(BUTTON_PIN) == LOW){
     delay(30); // Debounce
     if (digitalRead(BUTTON_PIN) == LOW){

       // Logical inversion of the control variable
       light = !light; // From "true" to "false" and vice versa

       // Check the state of the control variable
       if (light){ // If true (true)
         digitalWrite(LED_PIN, HIGH); // Turn on LED L
       }
       else { // If it's false (false)
         digitalWrite(LED_PIN, LOW); // Turn off LED L
       }

       while(digitalRead(BUTTON_PIN) == LOW); // Locks the code while the button is pressed
      
     }
   }

}

Understanding the Code

In the global declarations at the beginning of this project's code, in addition to the variables that store the pins connected to the button and the LED, we also have the declaration of the auxiliary boolean variable light, which will be responsible for turning the LED on or off when the button is pressed.

The code settings (function void setup()) are exactly the same as the previous project, just configuring the pins as input and output.

When looping through the code, we check with the help of a debounce (delay() of 30 milliseconds to filter noise) if the button was pressed through the condition if (digitalRead(BUTTON_PIN) == LOW). If the button is pressed, the conditions will be true by the debounce and the variable light will have its logical state inverted. That is, as it is initially false, it will be true after the first button press, and so on. Once this is done, it is checked if the variable light is true and, if so, LED L will be turned on. If it is false, LED L will be off. Finally, the empty while(digitalRead(BUTTON_PIN) == LOW) condition ensures that the code does not execute anything while the button is pressed. This prevents the variable light, and consequently the LED, from continuously changing state while the button is pressed.

What Must Happen

After uploading the code to the board, press the button and release it. You will see that LED L will stay turned on or off until the button is pressed and released again, as in the following GIF.

Final Result

Going Beyond

The LED L controlled in the examples above is just a demonstration of a possible action when the Vespa button is pressed, but the possibilities are not limited to this. With this button, it is possible to control the sending of MQTT messages over Wi-Fi to save sensor readings to an IoT dashboard, for example, or even reverse the rotation of a DC motor that is being controlled by the Vespa. Anyway, the possibilities are endless with such a simple board functionality.

In addition, we also have several other tutorials demonstrating all the features of Vespa.

Conclusion

In this tutorial we saw how to configure and read the GPIO connected to the integrated Vespa button in simple examples of LED L control.

Reading Vespa Button

Introduction

List of Materials

Lista completa de produtos

Vespa

Cabo USB Micro B 80cm

Direct Activation

Code

Understanding the Code

What Must Happen

Activation With Memory

Code

Understanding the Code

What Must Happen

Going Beyond

Conclusion