Expand 3 Click

Expand 3 Click is a compact add-on board providing general-purpose I/O expansion. This board features the DS2408, an 8-channel programmable I/O expander from Analog Devices. The DS2408 has a factory-lasered 64-bit registration number, enabling multiple Expand 3 Click boards™ to be connected on the same data line, communicating with the host MCU through a standard Dallas Semiconductor 1-Wire interface (15.3kbps or 100kbps). PIO outputs are configured as open-drain and provide a maximum on-resistance of 100Ω.

Click Product page

Click library

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

Software Support

We provide a library for the Expand 3 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 Expand 3 Click driver.

Standard key functions :

• expand3_cfg_setup Config Object Initialization function.

  void expand3_cfg_setup ( expand3_cfg_t *cfg );

• expand3_init Initialization function.

  err_t expand3_init ( expand3_t *ctx, expand3_cfg_t *cfg );

• expand3_default_cfg Click Default Configuration function.

  err_t expand3_default_cfg ( expand3_t *ctx );

Example key functions :

• expand3_write_state This function writes data to the PIO output-latch state register which controls the open-drain output transistors of the PIO channels.

  err_t expand3_write_state ( expand3_t *ctx, uint8_t state );

• expand3_read_last_state This function reads the latest data written to the PIO using

  err_t expand3_read_last_state ( expand3_t *ctx, uint8_t *last_state );

• expand3_read_current_state This function reads the current logic state of the PIO pins.

  err_t expand3_read_current_state ( expand3_t *ctx, uint8_t *curr_state );

Example Description

This example demonstrates the use of Expand 3 Click board by setting and reading the port state.

The demo application is composed of two sections :

Application Init

Initializes the driver and performs the Click default configuration.

void application_init ( void )
{
    log_cfg_t log_cfg;  /**< Logger config object. */
    expand3_cfg_t expand3_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.
    expand3_cfg_setup( &expand3_cfg );
    EXPAND3_MAP_MIKROBUS( expand3_cfg, MIKROBUS_1 );
    if ( ONE_WIRE_ERROR == expand3_init( &expand3, &expand3_cfg ) ) 
    {
        log_error( &logger, " Communication init." );
        for ( ; ; );
    }

    if ( EXPAND3_ERROR == expand3_default_cfg ( &expand3 ) )
    {
        log_error( &logger, " Default configuration." );
        for ( ; ; );
    }

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

Application Task

Writes a counter data to the port output pins and reads the status of the same port input pins approximately every 500ms. All data are displayed on the USB UART.

void application_task ( void )
{
    static uint8_t out_state = 0;
    static uint8_t in_state = 0;
    if ( ( EXPAND3_OK == expand3_write_state ( &expand3, out_state ) ) && 
         ( EXPAND3_OK == expand3_read_last_state ( &expand3, &out_state ) ) )
    {
        log_printf( &logger, " Output state: 0x%.2X\r\n\n", out_state++ );
    }
    if ( EXPAND3_OK == expand3_read_current_state ( &expand3, &in_state ) )
    {
        log_printf( &logger, " Input state: 0x%.2X\r\n\n", in_state );
    }
    Delay_ms ( 500 );
}

Note

The PIO pins are in the open-drain mode, therefore a pull-up resistor must be added to each pin. This Click board can be used in a combination with an EasyLED [MIKROE-571] and EasyPULL [MIKROE-575] boards.

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.Expand3

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.