LDC Touch Click

LDC Touch Click is a compact add-on board optimized for inductive touch applications. This board features the LDC3114-Q1, a four-channel inductance-to-digital converter for low-power proximity and touch-button sensing from Texas Instruments. It comes with an adjustable sensitivity per input channel and operational power mode selection and measures frequency shifts caused by micro-deflection in the conductive targets formed by button presses. These presses are reported through a compatible I2C interface beside four LED indicators for its visual indication. This Click board™ enables touch button design for human-machine interface and precise linear position sensing of metal targets for automotive, consumer, and industrial applications by allowing access to the raw data representing the inductance value.

Click Product page

Click library

• Author : Stefan Filipovic
• Date : May 2022.
• Type : I2C type

Software Support

We provide a library for the LDC Touch 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 LDC Touch Click driver.

Standard key functions :

• ldctouch_cfg_setup Config Object Initialization function.

  void ldctouch_cfg_setup ( ldctouch_cfg_t *cfg );

• ldctouch_init Initialization function.

  err_t ldctouch_init ( ldctouch_t *ctx, ldctouch_cfg_t *cfg );

• ldctouch_default_cfg Click Default Configuration function.

  err_t ldctouch_default_cfg ( ldctouch_t *ctx );

Example key functions :

• ldctouch_get_int_pin This function returns the INT pin logic state.

  uint8_t ldctouch_get_int_pin ( ldctouch_t *ctx );

• ldctouch_get_data This function reads status, out_state, and all buttons raw data.

  err_t ldctouch_get_data ( ldctouch_t *ctx, ldctouch_data_t *button_data );

• ldctouch_set_operation_mode This function sets the operation mode.

  err_t ldctouch_set_operation_mode ( ldctouch_t *ctx, uint8_t mode );

Example Description

This example demonstrates the use of LDC Touch Click board by configuring the buttons to trigger on finger press, and reading the buttons state in the loop.

The demo application is composed of two sections :

Application Init

Initializes the driver and configures the buttons to be active on finger press.

void application_init ( void )
{
    log_cfg_t log_cfg;  /**< Logger config object. */
    ldctouch_cfg_t ldctouch_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.
    ldctouch_cfg_setup( &ldctouch_cfg );
    LDCTOUCH_MAP_MIKROBUS( ldctouch_cfg, MIKROBUS_1 );
    if ( I2C_MASTER_ERROR == ldctouch_init( &ldctouch, &ldctouch_cfg ) ) 
    {
        log_error( &logger, " Communication init." );
        for ( ; ; );
    }

    if ( LDCTOUCH_ERROR == ldctouch_default_cfg ( &ldctouch ) )
    {
        log_error( &logger, " Default configuration." );
        for ( ; ; );
    }

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

Application Task

Waits for the button active event interrupt and then reads and displays the buttons state and their raw data on the USB UART every 200ms approximately.

void application_task ( void )
{
    static bool button_active = true;
    if ( !ldctouch_get_int_pin ( &ldctouch ) )
    {
        ldctouch_data_t button_data;
        if ( LDCTOUCH_OK == ldctouch_get_data ( &ldctouch, &button_data ) )
        {
            button_active = true;
            log_printf ( &logger, " Active button: -" ); 
            for ( uint8_t cnt = 0; cnt < 4; cnt++ )
            {
                if ( button_data.out_state & ( 1 << cnt ) )
                {
                    log_printf ( &logger, " %u - ", ( uint16_t ) cnt ); 
                }
            }
            log_printf ( &logger, "\r\n Button 0 raw data: %d\r\n", button_data.ch0_raw_button );
            log_printf ( &logger, " Button 1 raw data: %d\r\n", button_data.ch1_raw_button );
            log_printf ( &logger, " Button 2 raw data: %d\r\n", button_data.ch2_raw_button );
            log_printf ( &logger, " Button 3 raw data: %d\r\n\n", button_data.ch3_raw_button );
            Delay_ms ( 200 );
        }
    }
    else
    {
        if ( button_active )
        {
            button_active = false;
            log_printf ( &logger, " Active button: - none -\r\n" ); 
        }
    }
}

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.LDCTouch

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.