Intermediate
30 min

Bid farewell to frustrating volume fluctuations thanks to NJU72341 and STM32L496AG combo solution

Experience audio nirvana: Your volume, your way

Volume 2 Click with Discovery kit with STM32L496AG MCU

Published Jul 22, 2025

Click board™

Volume 2 Click

Dev. board

Discovery kit with STM32L496AG MCU

Compiler

NECTO Studio

MCU

STM32L496AG

Experience a higher level of audio quality and precision with our volume control device, which enhances clarity and fidelity for a more immersive listening experience

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Hardware Overview

How does it work?

Volume 2 Click is based on the NJU72341, a 2-channel I2C configurable electronic volume IC with an external mute control from JRC. The NJU72341 operates as an audio signal processor with many characteristics useful in an audio application, such as low noise typical of 2.0µVrms and low distortion of 0.002%. It controls two independent audio channels with a vast volume control range from 0 to 95dB with 1dB step offering zero-cross detection to protect against pop noise. This Click board™ is suitable for stereo and multi-channel audio systems. The NJU72341 has to receive a specific supply voltage to operate

appropriately, in this case, 12V. Unlike the Volume Click, which has a symmetrical power supply, we have only one positive power supply in this case. Bringing just a positive power supply, the noise generated by that power supply will transmit to the output, representing a side effect. For this purpose, Volume 2 Click employs a boost converter unit that combines MIC5235 and MIC2606, both from Microchip. MIC5235 provides 13V out of 5V from the mikroBUS™ power rail, which then the MIC2606, with a feature of massive noise suppression, lowers it to 12V and then supplies NJU72341, reducing the noise generated

at its output. Volume 2 Click communicates with MCU using a standard I2C 2-Wire interface, with a clock frequency up to 100kHz in the Standard and 400kHz in the Fast Mode. Also, the user can have external mute control configurable through the PWM pin of the mikroBUS™ socket labeled as MTE. This Click board™ can be operated only with a 5V logic voltage level. The board must perform appropriate logic voltage level conversion before using MCUs with different logic levels. Also, it comes equipped with a library containing functions and an example code that can be used as a reference for further development.

Volume 2 Click top side image
Volume 2 Click bottom side image

Features overview

Development board

The 32L496GDISCOVERY Discovery kit serves as a comprehensive demonstration and development platform for the STM32L496AG microcontroller, featuring an Arm® Cortex®-M4 core. Designed for applications that demand a balance of high performance, advanced graphics, and ultra-low power consumption, this kit enables seamless prototyping for a wide range of embedded solutions. With its innovative energy-efficient

architecture, the STM32L496AG integrates extended RAM and the Chrom-ART Accelerator, enhancing graphics performance while maintaining low power consumption. This makes the kit particularly well-suited for applications involving audio processing, graphical user interfaces, and real-time data acquisition, where energy efficiency is a key requirement. For ease of development, the board includes an onboard ST-LINK/V2-1

debugger/programmer, providing a seamless out-of-the-box experience for loading, debugging, and testing applications without requiring additional hardware. The combination of low power features, enhanced memory capabilities, and built-in debugging tools makes the 32L496GDISCOVERY kit an ideal choice for prototyping advanced embedded systems with state-of-the-art energy efficiency.

Discovery kit with STM32L496AG MCU double side image

Microcontroller Overview

MCU Card / MCU

STM32L496AG Image

Architecture

ARM Cortex-M4

MCU Memory (KB)

1024

Silicon Vendor

STMicroelectronics

Pin count

169

RAM (Bytes)

327680

Used MCU Pins

mikroBUS™ mapper

NC
NC
AN
NC
NC
RST
NC
NC
CS
NC
NC
SCK
NC
NC
MISO
NC
NC
MOSI
NC
NC
3.3V
Ground
GND
GND
Mute Control
PA0
PWM
NC
NC
INT
NC
NC
TX
NC
NC
RX
I2C Clock
PB8
SCL
I2C Data
PB7
SDA
Power Supply
5V
5V
Ground
GND
GND
1

Take a closer look

Click board™ Schematic

Volume 2 Click Schematic schematic

Step by step

Project assembly

Discovery kit with STM32H750XB MCU front image hardware assembly

Start by selecting your development board and Click board™. Begin with the Discovery kit with STM32L496AG MCU as your development board.

Discovery kit with STM32H750XB MCU front image hardware assembly
Thermo 21 Click front image hardware assembly
Prog-cut hardware assembly
Thermo 21 Click complete accessories setup image hardware assembly
Board mapper by product7 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
Discovery kit with STM32H750XB MCU NECTO MCU Selection Step hardware assembly
Necto No Display image step 8 hardware assembly
Necto image step 9 hardware assembly
Necto image step 10 hardware assembly
Necto image step 11 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 Volume 2 Click driver.

Key functions:

  • volume2_update_vol_data - This function updates the volume by using direct defined structure options

  • volume2_device_mute - This function is used to set mute on or off by controlling the mte pin

  • volume2_generic_write - This function writes a desired number of data bytes starting from the selected register by using I2C serial interface

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 Volume2 Click example
 *
 * # Description
 * This example shows how Volume 2 Click board can be used
 * for controlling the audio channels. Thanks to this, a
 * simple audio effect is created by switching volume from
 * right to left and vice versa.
 *
 * The demo application is composed of two sections :
 *
 * ## Application Init
 * UART LOG and I2C drivers are initialized, following the
 * default configuration. By default, both channels are set
 * to 9 dB gain with zero cross detection enabled.
 *
 * ## Application Task
 * The task performs and effect of switching the volume
 * from right to left channel and vice versa. Like playing
 * ping-pong with the sound.
 *
 * @author Stefan Nikolic
 *
 */

#include "board.h"
#include "log.h"
#include "volume2.h"

static volume2_t volume2;
static log_t logger;

static volume2_vol_data_t volume_upd_data;
static uint8_t rising_vol;
static uint8_t max_atten = 60;

void application_init ( void ) {
    log_cfg_t log_cfg;          /**< Logger config object. */
    volume2_cfg_t volume2_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.

    volume2_cfg_setup( &volume2_cfg );
    VOLUME2_MAP_MIKROBUS( volume2_cfg, MIKROBUS_1 );
    err_t init_flag = volume2_init( &volume2, &volume2_cfg );
    if ( init_flag == I2C_MASTER_ERROR ) {
        log_error( &logger, " Application Init Error. " );
        log_info( &logger, " Please, run program again... " );

        for ( ; ; );
    }

    volume2_default_cfg( &volume2 );
    Delay_ms ( 100 );
    log_info( &logger, " Application Task " );
}

void application_task ( void ) {
    for ( rising_vol = 0 ; rising_vol < max_atten ; rising_vol++ ) {
        volume_upd_data.attenuation_ch1 = rising_vol;
        volume_upd_data.attenuation_ch2 = max_atten - rising_vol;
        volume2_update_vol_data( &volume2, volume_upd_data );
        Delay_ms ( 50 );
    }
    Delay_ms ( 1000 );
    for ( rising_vol = 0 ; rising_vol < max_atten ; rising_vol++ ) {
        volume_upd_data.attenuation_ch1 = max_atten - rising_vol;
        volume_upd_data.attenuation_ch2 = rising_vol;
        volume2_update_vol_data( &volume2, volume_upd_data );
        Delay_ms ( 50 );
    }
    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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