Buttons, LEDs and buzzer together

What this example shows

Using the buttons to drive the LEDs and the buzzer on the same board. Each button lights one LED in its own colour while you hold it, and the buzzer plays the tone of the highest-numbered button you hold.

The example code

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ButtonInteraction.ino

/**
 **************************************************
 *
 * @file        ButtonInteraction.ino
 * @brief       Button interaction example for Soldered Button, LED & Buzzer Board
 *              Host: ESP32 WROVER-E
 *
 * Press a button to light its LED and sound the buzzer:
 *   BTN1 -> LED1 red,   1000 Hz
 *   BTN2 -> LED2 green, 2000 Hz
 *   BTN3 -> LED3 blue,  3000 Hz
 *
 * Multiple buttons can be pressed simultaneously.
 * Buzzer plays the highest pressed button's frequency.
 *
 * @authors     Fran Fodor @ soldered.com
 ***************************************************/

#include "ButtonLedBuzzerBoard-SOLDERED.h"

ButtonLedBuzzerBoard_Soldered board;

void setup()
{
    Wire.begin(); // if not using Qwiic, specify I2C pins: Wire.begin(21, 22)
    board.begin();
    delay(2000);

    board.setAllLEDs(0, 0, 0);
    board.setBuzzer(0);
}

void loop()
{
    uint8_t buttons = board.readButtons();

    bool btn1 = buttons & 0x01;
    bool btn2 = buttons & 0x02;
    bool btn3 = buttons & 0x04;

    board.setLED(0, btn3 ? 255 : 0, 0, 0);
    board.setLED(1, 0, btn2 ? 255 : 0, 0);
    board.setLED(2, 0, 0, btn1 ? 255 : 0);

    if (btn3)      board.setBuzzer(3000);
    else if (btn2) board.setBuzzer(2000);
    else if (btn1) board.setBuzzer(1000);
    else           board.setBuzzer(0);

    // remove delay for smooth tone
    delay(20);
}

This example also uses Wire, which is not part of the Soldered-Button-LED-Buzzer-Board library: it comes with your Arduino board package. Wire.begin() joins the I2C bus as a controller. Without Qwiic, the comment in the sketch shows how to pass your own I2C pins, for example Wire.begin(21, 22) on the ESP32 host the example was written for.

Expected result:

There is no serial output. While you hold a button:

Button	LED	Colour	Tone
BTN1	LED 2	Blue	1000 Hz
BTN2	LED 1	Green	2000 Hz
BTN3	LED 0	Red	3000 Hz

Hold several buttons and each of their LEDs lights, while the buzzer plays the tone of the highest-numbered button. Release them all and the LEDs and the buzzer go off.

Functions used

ButtonLedBuzzerBoard_Soldered(uint8_t address = BLB_DEFAULT_ADDRESS)returns None

Creates the board object and remembers its I2C address. All three LEDs start as off in the library's colour buffer. The example uses the default address, 0x30, which the board has with all three address switches OFF.

ReturnsConstructor; no return value.

Parameters

Type	Name	Description
`uint8_t`	`address`	The board's I2C address, `0x30` to `0x37` as set by the address switch. Defaults to `BLB_DEFAULT_ADDRESS` (`0x30`).

begin()returns void

Starts the I2C bus by calling Wire.begin(). Call it once in setup(), before any other function.

ReturnsNothing.

setAllLEDs(uint8_t r, uint8_t g, uint8_t b)returns void

Sets all three LEDs to the same colour and sends them to the board. setAllLEDs(0, 0, 0) turns every LED off.

ReturnsNothing.

Parameters

Type	Name	Description
`uint8_t`	`r`	Red brightness, `0` (off) to `255` (full).
`uint8_t`	`g`	Green brightness, `0` to `255`.
`uint8_t`	`b`	Blue brightness, `0` to `255`.

setBuzzer(uint16_t freq)returns void

Sends a tone frequency in Hz to the passive buzzer. The examples pass 0 to stop the tone.

ReturnsNothing.

Parameters

Type	Name	Description
`uint16_t`	`freq`	Tone frequency in Hz. The examples pass `0` to stop the tone.

readButtons()returns uint8_t

Reads the board's button register and returns the state of all three buttons in one byte. Bit 0 is BTN1, bit 1 is BTN2 and bit 2 is BTN3; a bit is 1 while its button is pressed. If the board does not answer, the function returns 0, which looks the same as no button pressed.

ReturnsThe button bits: 0x01 for BTN1, 0x02 for BTN2, 0x04 for BTN3, combined when several are pressed.

setLED(uint8_t index, uint8_t r, uint8_t g, uint8_t b)returns void

Sets the colour of one LED. The library keeps the colours of all three LEDs and sends all of them to the board each time, so the other two LEDs keep their colours. An index of 3 or more is ignored.

ReturnsNothing.

Parameters

Type	Name	Description
`uint8_t`	`index`	Which LED, `0` to `2`.
`uint8_t`	`r`	Red brightness, `0` (off) to `255` (full).
`uint8_t`	`g`	Green brightness, `0` to `255`.
`uint8_t`	`b`	Blue brightness, `0` to `255`.

Putting it together

Every 20 ms the sketch reads all three buttons with one readButtons() call and splits the byte with the masks 0x01, 0x02 and 0x04. It then sets each LED to full brightness in its colour, or to off, so the LEDs always follow the buttons. The if chain checks BTN3 first, which is why the highest-numbered pressed button sets the tone.

The comment at the top of the sketch pairs BTN1 with red and BTN3 with blue. The code swaps those two colours, and the table above follows the code.

SourceOpen the verified Arduino exampleView the exact source used by this page.examples/ButtonInteraction/ButtonInteraction.ino

What this example shows​

The example code​

Functions used​

Putting it together​

What this example shows

The example code

Functions used

Putting it together