TouchKey 3 click

There are many kinds of touch sensors on the market, but every one of them has some unique features that make it stand out from the crowd. TouchKey 3 click is equipped with seven advanced capacitive sensors, based on the proprietary QTouch® technology. Besides quite a large number of QTouch® capacitive sensor channels, TouchKey 3 click also offers some additional features, such as the Adjacent Key Suppression (AKS®), a technology that ensures correct button press, even when the touch sensing pads are placed close to each other.

click Product page

Click library

• Author : MikroE Team
• Date : Dec 2019.
• Type : SPI type

Software Support

We provide a library for the TouchKey3 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 form compilers IDE(recommended way), or downloaded from our LibStock, or found on mikroE github account.

Library Description

This library contains API for TouchKey3 Click driver.

Standard key functions :

• Config Object Initialization function.

  void touchkey3_cfg_setup ( touchkey3_cfg_t *cfg );

• Initialization function.

  TOUCHKEY3_RETVAL touchkey3_init ( touchkey3_t ctx, touchkey3_cfg_t cfg );

• Click Default Configuration function.

  void touchkey3_default_cfg ( touchkey3_t *ctx );

Example key functions :

• Function executes one of the possible commands.

  uint8_t touchkey3_send_command ( touchkey3_t *ctx, uint8_t command );

• Function sends a request command, and returns the response.

  uint8_t touchkey3_send_request ( touchkey3_t ctx, uint8_t request, uint8_t p_response );

• Function reads from a selected configuration register.

  uint8_t touchkey3_get_data ( uint8_t data_address, uint8_t * read_data );

Examples Description

This click uses 7 capacitive sensing channels, with the #CHANGE pin routed to the INT pin of the mikroBUS™, so that an interrupt can be triggered if any of the sensors detect a touch event. This can be used to trigger an SPI read cycle only when the key is actually pressed, avoiding the need for constant polling of the sensor registers.

The demo application is composed of two sections :

Application Init

Initializes click driver and performs a soft reset of the click.

void application_init ( void )
{
    log_cfg_t log_cfg;
    touchkey3_cfg_t cfg;

    /** 
     * 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.

    touchkey3_cfg_setup( &cfg );
    TOUCHKEY3_MAP_MIKROBUS( cfg, MIKROBUS_1 );
    touchkey3_init( &touchkey3, &cfg );

    touchkey3_send_command( &touchkey3, TOUCHKEY3_CMD_RESET );
}

Application Task

Reads the status of the keys, and outputs a message if a key is touched.

void application_task ( void )
{ 
    touchkey3_send_request( &touchkey3, TOUCHKEY3_REQ_ALL_KEYS, &return_data );

    for ( counter = 0; counter < 7; counter++ )
    {
        if ( ( return_data[ 1 ] >> counter ) & 0x01 )
        {
            log_info( &logger, "Touch detected on key " );
            //Converts the key index into ascii character ( 0 - 7 -> '1' - '7')
            temp = counter + 49;
            log_info( &logger, "%d\r\n", temp );
            Delay_ms ( 1000 );
        }
    }
    Delay_ms ( 200 );
} 

The full application code, and ready to use projects can be installed directly form compilers IDE(recommneded) or found on LibStock page or mikroE GitHub accaunt.

Other mikroE Libraries used in the example:

• MikroSDK.Board
• MikroSDK.Log
• Click.TouchKey3

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.