LightHz click

LightHz Click is a compact add-on board that effectively measures ambient light intensity. This board features the TL2L30BR, a programmable light-to-frequency converter from ams. The sensor outputs either a pulse train or a square wave (50% duty cycle) with a frequency directly proportional to light intensity (irradiance). It has programmable sensitivity and full-scale output frequency and could be used as a rough color detector with a selectable frequency range.

click Product page

Click library

• Author : Stefan Filipovic
• Date : Feb 2024.
• Type : GPIO type

Software Support

We provide a library for the LightHz 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 LightHz Click driver.

Standard key functions :

• lighthz_cfg_setup Config Object Initialization function.

  void lighthz_cfg_setup ( lighthz_cfg_t *cfg );

• lighthz_init Initialization function.

  err_t lighthz_init ( lighthz_t *ctx, lighthz_cfg_t *cfg );

Example key functions :

• lighthz_set_sensitivity This function sets the sensor sensitivity.

  void lighthz_set_sensitivity ( lighthz_t *ctx, uint8_t mode );

• lighthz_set_frequency_scaling This function sets the sensor frequency scaling.

  void lighthz_set_frequency_scaling ( lighthz_t *ctx, uint8_t mode );

• lighthz_get_freq_pin This function returns the freq pin logic state.

  uint8_t lighthz_get_freq_pin ( lighthz_t *ctx );

Example Description

This example demonstrates the use of LightHz click board by measuring and displaying the frequency of clock output signal. The higher the light intensity the higher the frequency.

The demo application is composed of two sections :

Application Init

Initializes the driver and sets the sensitivity mode and frequency scaling in case the onboard jumpers are set to MCU instead to ON-BRD.

void application_init ( void )
{
    log_cfg_t log_cfg;  /**< Logger config object. */
    lighthz_cfg_t lighthz_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.
    lighthz_cfg_setup( &lighthz_cfg );
    LIGHTHZ_MAP_MIKROBUS( lighthz_cfg, MIKROBUS_1 );
    if ( DIGITAL_OUT_UNSUPPORTED_PIN == lighthz_init( &lighthz, &lighthz_cfg ) ) 
    {
        log_error( &logger, " Communication init." );
        for ( ; ; );
    }

    lighthz_set_sensitivity ( &lighthz, LIGHTHZ_SENS_100X );
    lighthz_set_frequency_scaling ( &lighthz, LIGHTHZ_FSCALE_100 );

    log_info( &logger, " Application Task " );
}

Application Task

Measures the clock output frequency using the polling method and delays. The results are being sent to the USB UART.

void application_task ( void )
{
    uint32_t freq_cnt = 0;
    uint16_t sample_cnt = 0;

    // Wait for the clock rising edge signal
    while ( !hal_ll_gpio_read_pin_input( &lighthz.freq.pin ) );

    // A loop for measuring the clock frequency counts. It's not an ideal implementation.
    // Here we should use an external interrupt on the clock pin rising edge and a timer interrupt
    // for the best accuracy, however, those interrupt features have not yet been implemented in the SDK. 
    while ( ( sample_cnt < LIGHTHZ_SAMPLE_COUNTS ) && ( freq_cnt < LIGHTHZ_MAX_COUNTS_PER_S ) )
    {
        // A single iteration in the loops below should take as close to 10us as possible
        // So to improve the measurement accuracy adjust the delay below for your system
        while ( hal_ll_gpio_read_pin_input( &lighthz.freq.pin ) )
        {
            freq_cnt++;
            Delay_us ( LIGHTHZ_DELAY_US );
        }
        while ( !hal_ll_gpio_read_pin_input( &lighthz.freq.pin ) )
        {
            freq_cnt++;
            Delay_us ( LIGHTHZ_DELAY_US );
        }
        sample_cnt++;
    }
    freq_cnt /= sample_cnt;

    // The higher the light intensity the higher the frequency.
    log_printf( &logger, " Frequency: %.1f Hz\r\n\n", ( float ) LIGHTHZ_MAX_COUNTS_PER_S / freq_cnt );

    Delay_ms ( 1000 );
}

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.LightHz

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. UART terminal is available in all MikroElektronika compilers.