RTC 21 Click

RTC 21 Click is a compact add-on board that accurately keeps the time of the day. This board features the PT7C4311, an I2C-configurable real-time clock module with programmable square-wave output from Diodes Incorporated. The PT7C4311 includes time and calendar functions providing various information such as hour, minute, second, day, date, month, year, and century. It operates in a 24-hour format indicator, has automatic leap year compensation, and low power consumption, allowing it to be used with a single button cell battery for an extended period.

Click Product page

Click library

• Author : Stefan Filipovic
• Date : Feb 2023.
• Type : I2C type

Software Support

We provide a library for the RTC 21 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 RTC 21 Click driver.

Standard key functions :

• rtc21_cfg_setup Config Object Initialization function.

  void rtc21_cfg_setup ( rtc21_cfg_t *cfg );

• rtc21_init Initialization function.

  err_t rtc21_init ( rtc21_t *ctx, rtc21_cfg_t *cfg );

Example key functions :

• rtc21_set_time This function sets the starting time values - second, minute and hour.

  err_t rtc21_set_time ( rtc21_t *ctx, rtc21_time_t *time );

• rtc21_set_date This function sets the starting date values - day of week, day, month and year.

  err_t rtc21_set_date ( rtc21_t *ctx, rtc21_date_t *date );

• rtc21_read_time This function reads the current time values - second, minute and hour.

  err_t rtc21_read_time ( rtc21_t *ctx, rtc21_time_t *time );

Example Description

This example demonstrates the use of RTC 21 Click board by reading and displaying the time and date values.

The demo application is composed of two sections :

Application Init

Initializes the driver and logger and then sets the starting time and date.

void application_init ( void )
{
    log_cfg_t log_cfg;  /**< Logger config object. */
    rtc21_cfg_t rtc21_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.
    rtc21_cfg_setup( &rtc21_cfg );
    RTC21_MAP_MIKROBUS( rtc21_cfg, MIKROBUS_1 );
    if ( I2C_MASTER_ERROR == rtc21_init( &rtc21, &rtc21_cfg ) ) 
    {
        log_error( &logger, " Communication init." );
        for ( ; ; );
    }

    time.hour = 23;
    time.minute = 59;
    time.second = 50;
    if ( RTC21_OK == rtc21_set_time ( &rtc21, &time ) )
    {
        log_printf( &logger, " Set time: %.2u:%.2u:%.2u\r\n", 
                    ( uint16_t ) time.hour, ( uint16_t ) time.minute, ( uint16_t ) time.second );
    }
    date.day_of_week = RTC21_SATURDAY;
    date.day = 31;
    date.month = 12;
    date.year = 22;
    if ( RTC21_OK == rtc21_set_date ( &rtc21, &date ) )
    {
        log_printf( &logger, " Set date: %s, %.2u.%.2u.20%.2u.\r\n", 
                    rtc21_get_day_of_week_name ( date.day_of_week ),
                    ( uint16_t ) date.day, ( uint16_t ) date.month, ( uint16_t ) date.year );
    }
    Delay_ms ( 100 );

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

Application Task

Reads and displays on the USB UART the current time and date values once per second.

void application_task ( void )
{
    if ( RTC21_OK == rtc21_read_time ( &rtc21, &time ) )
    {
        log_printf( &logger, " Time: %.2u:%.2u:%.2u\r\n", 
                    ( uint16_t ) time.hour, ( uint16_t ) time.minute, ( uint16_t ) time.second );
    }
    if ( RTC21_OK == rtc21_read_date ( &rtc21, &date ) )
    {
        log_printf( &logger, " Date: %s, %.2u.%.2u.20%.2u.\r\n", 
                    rtc21_get_day_of_week_name ( date.day_of_week ),
                    ( uint16_t ) date.day, ( uint16_t ) date.month, ( uint16_t ) date.year );
    }
    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.RTC21

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.