iButton Click

iButton Click - is an iButton™ probe Click board™. The iButton is a Analog Devices technology based on Analog's 1-Wire® communication protocol, and a chip usually packed in a robust stainless steel casing. The button-shaped iButton device has two contacts - the lid and the base. These contacts carry the necessary connections down to a sensitive silicone chip, embedded inside the metal button. When the iButton touches the reader probe on the Click board™, it establishes the communication with the host MCU, via the 1-Wire® interface. The communication is almost instant, so it is enough to press the iButton lightly to the probe contacts.

Click Product page

Click library

• Author : Stefan Filipovic
• Date : Feb 2024.
• Type : One Wire type

Software Support

We provide a library for the iButton 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 iButton Click driver.

Standard key functions :

• ibutton_cfg_setup Config Object Initialization function.

  void ibutton_cfg_setup ( ibutton_cfg_t *cfg );

• ibutton_init Initialization function.

  err_t ibutton_init ( ibutton_t *ctx, ibutton_cfg_t *cfg );

Example key functions :

• ibutton_add_key This function reads the ROM address from a DS1990A Serial Number iButton and stores it in the ctx->key_rom buffer.

  err_t ibutton_add_key ( ibutton_t *ctx );

• ibutton_remove_keys This function removes all stored keys by clearing the ctx->key_rom buffer.

  void ibutton_remove_keys ( ibutton_t *ctx );

• ibutton_check_key This function reads the ROM address from a DS1990A Serial Number iButton and checks if it is already stored in the ctx->key_rom buffer.

  err_t ibutton_check_key ( ibutton_t *ctx );

Example Description

This example demonstrates the use of the iButton Click boards by registering a DS1990A Serial Number iButton key and then waiting until a key is detected on the reader and identifying if the key matches one of those stored in RAM.

The demo application is composed of two sections :

Application Init

Initializes the driver and registers a new DS1990A Serial Number iButton key and stores it in RAM.

void application_init ( void )
{
    log_cfg_t log_cfg;  /**< Logger config object. */
    ibutton_cfg_t ibutton_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.
    ibutton_cfg_setup( &ibutton_cfg );
    IBUTTON_MAP_MIKROBUS( ibutton_cfg, MIKROBUS_1 );
    if ( ONE_WIRE_ERROR == ibutton_init( &ibutton, &ibutton_cfg ) ) 
    {
        log_error( &logger, " Communication init." );
        for ( ; ; );
    }

    ibutton_register_keys ( &ibutton, NUMBER_OF_KEYS );

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

Application Task

Waits until a key is detected on the reader, and checks if there's a key found in the library that matches the one it has just read. All data is being logged on the USB UART where you can track the program flow.

void application_task ( void )
{
    err_t error_flag = IBUTTON_OK;
    ibutton_led_indication ( &ibutton, IBUTTON_LED_DISABLE );
    log_printf( &logger, " >>> Waiting for a key <<<\r\n" );
    do
    {
        ibutton_led_indication ( &ibutton, IBUTTON_LED_WAIT_KEY );
        error_flag = ibutton_check_key ( &ibutton );
    }
    while ( IBUTTON_ERROR == error_flag );

    ibutton_led_indication ( &ibutton, IBUTTON_LED_DISABLE );
    if ( IBUTTON_OK == error_flag )
    {
        log_printf( &logger, " MATCH, access allowed!\r\n" );
        ibutton_led_indication ( &ibutton, IBUTTON_LED_SUCCESS );
    }
    else if ( IBUTTON_KEY_NO_MATCH == error_flag )
    {
        log_printf( &logger, " NO MATCH, access denied!\r\n" );
        ibutton_led_indication ( &ibutton, IBUTTON_LED_WRONG_KEY );
    }
    ibutton_led_indication ( &ibutton, IBUTTON_LED_DISABLE );
    log_printf( &logger, "--------------------------------\r\n\n" );
    Delay_ms ( 500 );
}

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.iButton

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.