Intermediate
30 min

Achieve premium audio quality with LM4811 and STM32F031K6

Unleash your headphones' full potential with our amplifier

Headphone AMP Click with Nucleo 32 with STM32F031K6 MCU

Published Oct 01, 2024

Click board™

Headphone AMP Click

Dev. board

Nucleo 32 with STM32F031K6 MCU

Compiler

NECTO Studio

MCU

STM32F031K6

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

Nucleo 32 with STM32F031K6 MCU board provides an affordable and flexible platform for experimenting with STM32 microcontrollers in 32-pin packages. Featuring Arduino™ Nano connectivity, it allows easy expansion with specialized shields, while being mbed-enabled for seamless integration with online resources. The

board includes an on-board ST-LINK/V2-1 debugger/programmer, supporting USB reenumeration with three interfaces: Virtual Com port, mass storage, and debug port. It offers a flexible power supply through either USB VBUS or an external source. Additionally, it includes three LEDs (LD1 for USB communication, LD2 for power,

and LD3 as a user LED) and a reset push button. The STM32 Nucleo-32 board is supported by various Integrated Development Environments (IDEs) such as IAR™, Keil®, and GCC-based IDEs like AC6 SW4STM32, making it a versatile tool for developers.

Nucleo 32 with STM32F031K6 MCU double side image

Microcontroller Overview

MCU Card / MCU

default

Architecture

ARM Cortex-M0

MCU Memory (KB)

32

Silicon Vendor

STMicroelectronics

Pin count

32

RAM (Bytes)

4096

You complete me!

Accessories

Click Shield for Nucleo-32 is the perfect way to expand your development board's functionalities with STM32 Nucleo-32 pinout. The Click Shield for Nucleo-32 provides two mikroBUS™ sockets to add any functionality from our ever-growing range of Click boards™. We are fully stocked with everything, from sensors and WiFi transceivers to motor control and audio amplifiers. The Click Shield for Nucleo-32 is compatible with the STM32 Nucleo-32 board, providing an affordable and flexible way for users to try out new ideas and quickly create prototypes with any STM32 microcontrollers, choosing from the various combinations of performance, power consumption, and features. The STM32 Nucleo-32 boards do not require any separate probe as they integrate the ST-LINK/V2-1 debugger/programmer and come with the STM32 comprehensive software HAL library and various packaged software examples. This development platform provides users with an effortless and common way to combine the STM32 Nucleo-32 footprint compatible board with their favorite Click boards™ in their upcoming projects.

Click Shield for Nucleo-32 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
PA11
RST
NC
NC
CS
NC
NC
SCK
NC
NC
MISO
NC
NC
MOSI
Power Supply
3.3V
3.3V
Ground
GND
GND
Clock Signal
PA8
PWM
Gain Control
PA12
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 Nucleo-144 front image hardware assembly

Start by selecting your development board and Click board™. Begin with the Nucleo 32 with STM32F031K6 MCU as your development board.

Click Shield for Nucleo-144 front image hardware assembly
Nucleo 144 with STM32L4A6ZG MCU front image hardware assembly
Stepper 22 Click front image hardware assembly
Prog-cut hardware assembly
Stepper 22 Click complete accessories setup image hardware assembly
Nucleo-32 with STM32 MCU 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
STM32 M4 Clicker HA MCU/Select 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

1. Application Output - In Debug mode, the 'Application Output' window enables real-time data monitoring, offering direct insight into execution results. Ensure proper data display by configuring the environment correctly using the provided tutorial.

2. UART Terminal - Use the UART Terminal to monitor data transmission via a USB to UART converter, allowing direct communication between the Click board™ and your development system. Configure the baud rate and other serial settings according to your project's requirements to ensure proper functionality. For step-by-step setup instructions, refer to the provided tutorial.

3. Plot Output - The Plot feature offers a powerful way to visualize real-time sensor data, enabling trend analysis, debugging, and comparison of multiple data points. To set it up correctly, follow the provided tutorial, which includes a step-by-step example of using the Plot feature to display Click board™ readings. To use the Plot feature in your code, use the function: plot(*insert_graph_name*, variable_name);. This is a general format, and it is up to the user to replace 'insert_graph_name' with the actual graph name and 'variable_name' with the parameter to be displayed.

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

The complete application code and a ready-to-use project are available through the NECTO Studio Package Manager for direct installation in the NECTO Studio. The application code can also be found on the MIKROE GitHub account.

/*!
 * @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 ( 1000 );
    Delay_ms ( 1000 );
    Delay_ms ( 1000 );
    Delay_ms ( 1000 );
    Delay_ms ( 1000 );
}

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 ( 1000 ); 
        Delay_ms ( 1000 );   
    }
    
    log_printf( &logger, "-------------------------\r\n" );
    Delay_ms ( 1000 );
    Delay_ms ( 1000 );
    Delay_ms ( 1000 );
    Delay_ms ( 1000 );
    Delay_ms ( 1000 );
    
    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 ( 1000 ); 
        Delay_ms ( 1000 );   
    }
       
    log_printf( &logger, "-------------------------\r\n" );
    Delay_ms ( 1000 );
    Delay_ms ( 1000 );
    Delay_ms ( 1000 );
    Delay_ms ( 1000 );
    Delay_ms ( 1000 );
}

int main ( void ) 
{
    /* Do not remove this line or clock might not be set correctly. */
    #ifdef PREINIT_SUPPORTED
    preinit();
    #endif
    
    application_init( );
    
    for ( ; ; ) 
    {
        application_task( );
    }

    return 0;
}

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

Additional Support

Resources

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