VU Meter click

VU Meter Click is a compact add-on board representing a volume unit meter that displays the intensity of an audio signal. This board features the LM3914, a monolithic integrated circuit that senses analog voltage levels and drives a 10-segment bar graph display from Texas Instruments. This Click board™ is manufactured with a sound detecting device (microphone), Op-Amp, and the LM3914, which gleams the bar graph display according to the sound’s quality. The LM3914 is an analog-controlled driver meaning it can control (turn ON or OFF) a display by an analog input voltage and eliminates the need for additional programming.

click Product page

Click library

• Author : Stefan Filipovic
• Date : Sep 2021.
• Type : SPI type

Software Support

We provide a library for the VUMeter Click as well as a demo application (example), developed using MikroElektronika compilers. The demo can run on all the main MikroElektronika development boards.

Package can be downloaded/installed directly from NECTO Studio Package Manager(recommended way), downloaded from our LibStock™ or found on Mikroe github account.

Library Description

This library contains API for VUMeter Click driver.

Standard key functions :

• vumeter_cfg_setup Config Object Initialization function.

  void vumeter_cfg_setup ( vumeter_cfg_t *cfg );

• vumeter_init Initialization function.

  err_t vumeter_init ( vumeter_t *ctx, vumeter_cfg_t *cfg );

Example key functions :

• vumeter_read_an_pin_voltage This function reads results of AD conversion of the AN pin and converts them to proportional voltage level.

  err_t vumeter_read_an_pin_voltage ( vumeter_t *ctx, float *data_out );

• vumeter_set_gain_level This function sets the input signal gain level (the microphone sensitivity).

  err_t vumeter_set_gain_level ( vumeter_t *ctx, uint8_t gain_lvl );

• vumeter_calculate_vu_level This function calculates VU level from the analog voltage input.

  float vumeter_calculate_vu_level ( vumeter_t *ctx, uint16_t sample_rate_ms );

Example Description

This example demonstrates the use of VU Meter click board.

The demo application is composed of two sections :

Application Init

Initializes the driver and sets the gain level (the microphone sensitivity) to maximum.

void application_init ( void )
{
    log_cfg_t log_cfg;          /**< Logger config object. */
    vumeter_cfg_t vumeter_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.

    vumeter_cfg_setup( &vumeter_cfg );
    VUMETER_MAP_MIKROBUS( vumeter_cfg, MIKROBUS_1 );
    err_t init_flag  = vumeter_init( &vumeter, &vumeter_cfg );
    if ( SPI_MASTER_ERROR == init_flag )
    {
        log_error( &logger, " Application Init Error. " );
        log_info( &logger, " Please, run program again... " );

        for ( ; ; );
    }

    vumeter_set_gain_level ( &vumeter, VUMETER_GAIN_LEVEL_MAX );
    log_info( &logger, " Application Task " );
}

Application Task

Calculates VU level from the analog voltage read from AN pin, and displays the results on the USB UART approximately every 100ms.

void application_task ( void )
{
    log_printf( &logger, " VU level: %.3f VU\r\n", vumeter_calculate_vu_level ( &vumeter, 100 ) );
}

The full application code, and ready to use projects can be installed directly from NECTO Studio Package Manager(recommended way), downloaded from our LibStock™ or found on Mikroe github account.

Other Mikroe Libraries used in the example:

• MikroSDK.Board
• MikroSDK.Log
• Click.VUMeter

Additional notes and informations

Depending on the development board you are using, you may need USB UART click, USB UART 2 Click or RS232 Click to connect to your PC, for development systems with no UART to USB interface available on the board. The terminal available in all MikroElektronika compilers, or any other terminal application of your choice, can be used to read the message.