Intermediate
30 min

Achieve premium audio quality with LM4811 and ATmega328P

Unleash your headphones' full potential with our amplifier

Headphone AMP Click with Arduino UNO Rev3

Published Feb 14, 2024

Click board™

Headphone AMP Click

Dev Board

Arduino UNO Rev3

Compiler

NECTO Studio

MCU

ATmega328P

Experience the true power of your headphones with our amplifier, designed to maximize every detail and bring your music to life like never before

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Hardware Overview

How does it work?

Headphone AMP Click is based on the LM4811, a stereo, analog input headphone amplifier with digital volume control from Texas Instruments. This headphone amplifier is designed to provide high-quality output power using few external components and does not require bootstrap capacitors or snubber networks for stability improvement. The maximum power delivered by the LM4811 headphone amplifier is 105mW per channel into 16Ω and 70mW with 16Ω load impedance. Other prominent features of the ML4811 also include digital volume control, "Click and Pop" suppression circuitry, and a low shutdown current of 0.3μA. This Click board™ communicates with MCU using several GPIO pins.

The signals from the CLK and U/D pins routed to the PWM and INT pins of the mikroBUS™ socket control the LM4811's gain. The gain will increase or decrease by a 3dB step depending on the logic voltage level applied to the U/D pin at each rising edge of the CLK signal. A logic high voltage level applied to the U/D pin causes the gain to increase by 3dB at each rising edge of the CLK signal and vice versa. The amplifier's gain is set to a default value of 0dB upon the devices' Power-On features. Sixteen discrete gain settings range from +12dB maximum to −33dB minimum. The unity-gain stable LM4811 also features an externally controlled, active-high, micro-power consumption Shutdown mode, available on the RST pin of the

mikroBUS™ socket, to reduce power consumption while not in use. However, when coming out of Shutdown mode, the LM4811 will revert to its previous gain setting. Alongside all these features, the LM4811 also has an internal thermal shutdown protection mechanism. This Click board™ can operate with either 3.3V or 5V logic voltage levels selected via the VCC SEL jumper. This way, both 3.3V and 5V capable MCUs can use the communication lines properly. Also, this Click board™ comes equipped with a library containing easy-to-use functions and an example code that can be used as a reference for further development.

Headphone AMP Click top side image
Headphone AMP Click bottom side image

Features overview

Development board

Arduino UNO is a versatile microcontroller board built around the ATmega328P chip. It offers extensive connectivity options for various projects, featuring 14 digital input/output pins, six of which are PWM-capable, along with six analog inputs. Its core components include a 16MHz ceramic resonator, a USB connection, a power jack, an

ICSP header, and a reset button, providing everything necessary to power and program the board. The Uno is ready to go, whether connected to a computer via USB or powered by an AC-to-DC adapter or battery. As the first USB Arduino board, it serves as the benchmark for the Arduino platform, with "Uno" symbolizing its status as the

first in a series. This name choice, meaning "one" in Italian, commemorates the launch of Arduino Software (IDE) 1.0. Initially introduced alongside version 1.0 of the Arduino Software (IDE), the Uno has since become the foundational model for subsequent Arduino releases, embodying the platform's evolution.

Arduino UNO Rev3 double side image

Microcontroller Overview

MCU Card / MCU

default

Architecture

AVR

MCU Memory (KB)

32

Silicon Vendor

Microchip

Pin count

28

RAM (Bytes)

2048

You complete me!

Accessories

Click Shield for Arduino UNO has two proprietary mikroBUS™ sockets, allowing all the Click board™ devices to be interfaced with the Arduino UNO board without effort. The Arduino Uno, a microcontroller board based on the ATmega328P, provides an affordable and flexible way for users to try out new concepts and build prototypes with the ATmega328P microcontroller from various combinations of performance, power consumption, and features. The Arduino Uno has 14 digital input/output pins (of which six can be used as PWM outputs), six analog inputs, a 16 MHz ceramic resonator (CSTCE16M0V53-R0), a USB connection, a power jack, an ICSP header, and reset button. Most of the ATmega328P microcontroller pins are brought to the IO pins on the left and right edge of the board, which are then connected to two existing mikroBUS™ sockets. This Click Shield also has several switches that perform functions such as selecting the logic levels of analog signals on mikroBUS™ sockets and selecting logic voltage levels of the mikroBUS™ sockets themselves. Besides, the user is offered the possibility of using any Click board™ with the help of existing bidirectional level-shifting voltage translators, regardless of whether the Click board™ operates at a 3.3V or 5V logic voltage level. Once you connect the Arduino UNO board with our Click Shield for Arduino UNO, you can access hundreds of Click boards™, working with 3.3V or 5V logic voltage levels.

Click Shield for Arduino UNO accessories 1 image

These standard small stereo earphones offer a high-quality listening experience with their top-notch stereo cable and connector. Designed for universal compatibility, they effortlessly connect to all MIKROE mikromedia and multimedia boards, making them an ideal choice for your electronic projects. With a rated power of 100mW, the earphones provide crisp audio across a broad frequency range from 20Hz to 20kHz. They boast a sensitivity of 100 ± 5dB and an impedance of 32Ω ± 15%, ensuring optimal sound quality. The Φ15mm speaker delivers clear and immersive audio. Cost-effective and versatile, these earphones are perfect for testing your prototype devices, offering an affordable and reliable audio solution to complement your projects.

Headphone AMP Click accessories image

Used MCU Pins

mikroBUS™ mapper

NC
NC
AN
Shutdown
PD2
RST
NC
NC
CS
NC
NC
SCK
NC
NC
MISO
NC
NC
MOSI
Power Supply
3.3V
3.3V
Ground
GND
GND
Clock Signal
PD6
PWM
Gain Control
PC3
INT
NC
NC
TX
NC
NC
RX
NC
NC
SCL
NC
NC
SDA
Power Supply
5V
5V
Ground
GND
GND
1

Take a closer look

Click board™ Schematic

Headphone AMP Click Schematic schematic

Step by step

Project assembly

Click Shield for Arduino UNO front image hardware assembly

Start by selecting your development board and Click board™. Begin with the Arduino UNO Rev3 as your development board.

Click Shield for Arduino UNO front image hardware assembly
Arduino UNO Rev3 front image hardware assembly
Charger 27 Click front image hardware assembly
Prog-cut hardware assembly
Charger 27 Click complete accessories setup image hardware assembly
Arduino UNO Rev3 Access MB 1 - upright/background hardware assembly
Necto image step 2 hardware assembly
Necto image step 3 hardware assembly
Necto image step 4 hardware assembly
Necto image step 5 hardware assembly
Necto image step 6 hardware assembly
Arduino UNO MCU Step hardware assembly
Necto No Display image step 8 hardware assembly
Necto image step 9 hardware assembly
Necto image step 10 hardware assembly
Debug Image Necto Step hardware assembly

Track your results in real time

Application Output via Debug Mode

1. Once the code example is loaded, pressing the "DEBUG" button initiates the build process, programs it on the created setup, and enters Debug mode.

2. After the programming is completed, a header with buttons for various actions within the IDE becomes visible. Clicking the green "PLAY" button starts reading the results achieved with the Click board™. The achieved results are displayed in the Application Output tab.

DEBUG_Application_Output

Software Support

Library Description

This library contains API for Headphone AMP Click driver.

Key functions:

  • headphoneamp_set_sound_volume - Headphone AMP set sound volume function

  • headphoneamp_volume_up - Headphone AMP set sound volume up function

  • headphoneamp_volume_down - Headphone AMP set sound volume down function

Open Source

Code example

This example can be found in NECTO Studio. Feel free to download the code, or you can copy the code below.

/*!
 * @file main.c
 * @brief Headphone AMP Click Example.
 *
 * # Description
 * This library contains API for the Headphone AMP click driver.
 * This demo application shows use of a Headphone AMP click board™.
 *
 * The demo application is composed of two sections :
 *
 * ## Application Init
 * Initialization of GPIO module and log UART.
 * After driver initialization the app set default settings, 
 * performs power-up sequence, sets a the sound volume of -12 dB.
 *
 * ## Application Task
 * This is an example that shows the use of Headphone AMP click board™.
 * The app performs circles the volume from -12 dB to 3 dB back and forth,
 * increase/decrement by 3dB.
 * Results are being sent to the Usart Terminal where you can track their changes.
 *
 * @author Nenad Filipovic
 *
 */

#include "board.h"
#include "log.h"
#include "headphoneamp.h"

static headphoneamp_t headphoneamp;   /**< Headphone AMP Click driver object. */
static log_t logger;                  /**< Logger object. */

void application_init ( void ) 
{
    log_cfg_t log_cfg;                    /**< Logger config object. */
    headphoneamp_cfg_t headphoneamp_cfg;  /**< Click config object. */

    /** 
     * Logger initialization.
     * Default baud rate: 115200
     * Default log level: LOG_LEVEL_DEBUG
     * @note If USB_UART_RX and USB_UART_TX 
     * are defined as HAL_PIN_NC, you will 
     * need to define them manually for log to work. 
     * See @b LOG_MAP_USB_UART macro definition for detailed explanation.
     */
    LOG_MAP_USB_UART( log_cfg );
    log_init( &logger, &log_cfg );
    log_info( &logger, " Application Init " );

    // Click initialization.

    headphoneamp_cfg_setup( &headphoneamp_cfg );
    HEADPHONEAMP_MAP_MIKROBUS( headphoneamp_cfg, MIKROBUS_1 );
    if ( headphoneamp_init( &headphoneamp, &headphoneamp_cfg ) == DIGITAL_OUT_UNSUPPORTED_PIN ) 
    {
        log_error( &logger, " Application Init Error. " );
        log_info( &logger, " Please, run program again... " );

        for ( ; ; );
    }
    headphoneamp_default_cfg ( &headphoneamp );
    log_info( &logger, " Application Task " );
    Delay_ms( 100 );
    
    log_printf( &logger, "-------------------------\r\n" );
    log_printf( &logger, "    Performs Power-up\r\n" );
    headphoneamp_power_up( &headphoneamp );
    Delay_ms( 100 );
    
    log_printf( &logger, "-------------------------\r\n" );
    log_printf( &logger, "  Set volume gain -12dB\r\n", HEADPHONEAMP_SOUND_VOLUME_NEG_12_dB );
    headphoneamp_set_sound_volume( &headphoneamp, HEADPHONEAMP_SOUND_VOLUME_NEG_12_dB ); 
    log_printf( &logger, "-------------------------\r\n" );
    Delay_ms( 5000 );
}

void application_task ( void ) 
{
    for ( uint8_t n_cnt = 0; n_cnt < 5; n_cnt++ ) {
        log_printf( &logger, "    Turning volume up\r\n" );
        headphoneamp_volume_up ( &headphoneamp ); 
        Delay_ms( 2000 );    
    }
    
    log_printf( &logger, "-------------------------\r\n" );
    Delay_ms( 5000 );
    
    for ( uint8_t n_cnt = 0; n_cnt < 5; n_cnt++ ) {
        log_printf( &logger, "   Turning volume down\r\n" );
        headphoneamp_volume_down ( &headphoneamp ); 
        Delay_ms( 2000 );    
    }
       
    log_printf( &logger, "-------------------------\r\n" );
    Delay_ms( 5000 );
}

void main ( void ) 
{
    application_init( );

    for ( ; ; ) 
    {
        application_task( );
    }
}

// ------------------------------------------------------------------------ END

Additional Support

Resources

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