Intermediate
30 min

Experience RTC excellence today with PT7C4311 and STM32F407VGT6

Timing is everything: Elevate your projects with our RTC solution

RTC 21 Click with Clicker 4 for STM32F4

Published Dec 29, 2023

Click board™

RTC 21 Click

Dev Board

Clicker 4 for STM32F4

Compiler

NECTO Studio

MCU

STM32F407VGT6

Integrate efficient real-time clock into your solution for precise event timing and seamless synchronization

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Hardware Overview

How does it work?

RTC 21 Click is based on the PT7C4311, an ultra-low power, real-time clock (RTC) time-keeping device from Diodes Incorporated. The PT7C4311 is configured to transmit calendar and time data to the MCU (24-hour format) based on a 32.768kHz quartz crystal and comes with 56 bytes of general-purpose RAM. It reads and writes clock/calendar data from and to the MCU in units ranging from seconds to the last two digits of the calendar year, providing seconds, minutes, hours, dates, days, months, year, and century information.

The end-of-the-month date is automatically adjusted for months with fewer than 31 days, including corrections for the leap year until 2100. This Click board™ communicates with MCU using the standard I2C 2-Wire interface to read data and configure settings, supporting a Fast Mode operation up to 400kHz. It also incorporates one open-drain output labeled FT, which can be used as a frequency test signal (512Hz square-wave password for frequency test purposes) or as a register-configurable output DC level when

square-wave is disabled. The PT7C4311 also includes an automatic backup switchover circuit, allowing it to be used with a single-button cell battery for an extended period. This Click board™ can operate with either 3.3V or 5V logic voltage levels selected via the VCC SEL jumper. This way, both 3.3V and 5V capable MCUs can use the communication lines properly. Also, this Click board™ comes equipped with a library containing easy-to-use functions and an example code that can be used for further development.

RTC 21 Click top side image
RTC 21 Click bottom side image

Features overview

Development board

Clicker 4 for STM32F4 is a compact development board designed as a complete solution that you can use to quickly build your own gadgets with unique functionalities. Featuring an STM32F407VGT6 MCU, four mikroBUS™ sockets for Click boards™ connectivity, power management, and more, it represents a perfect solution for the rapid development of many different types of applications. At its core is an STM32F407VGT6 MCU, a powerful microcontroller by STMicroelectronics based on the high-performance

Arm® Cortex®-M4 32-bit processor core operating at up to 168 MHz frequency. It provides sufficient processing power for the most demanding tasks, allowing Clicker 4 to adapt to any specific application requirements. Besides two 1x20 pin headers, four improved mikroBUS™ sockets represent the most distinctive connectivity feature, allowing access to a huge base of Click boards™, growing on a daily basis. Each section of Clicker 4 is clearly marked, offering an intuitive and clean interface. This makes working with the

development board much simpler and, thus, faster. The usability of Clicker 4 doesn’t end with its ability to accelerate the prototyping and application development stages: it is designed as a complete solution that can be implemented directly into any project, with no additional hardware modifications required. Four mounting holes [4.2mm/0.165”] at all four corners allow simple installation by using mounting screws.

Clicker 4 for STM32F4 double image

Microcontroller Overview

MCU Card / MCU

default

Architecture

ARM Cortex-M4

MCU Memory (KB)

10

Silicon Vendor

STMicroelectronics

Pin count

100

RAM (Bytes)

100

Used MCU Pins

mikroBUS™ mapper

NC
NC
AN
NC
NC
RST
NC
NC
CS
NC
NC
SCK
NC
NC
MISO
NC
NC
MOSI
Power Supply
3.3V
3.3V
Ground
GND
GND
NC
NC
PWM
Frequency Test/DC Level
PD0
INT
NC
NC
TX
NC
NC
RX
I2C Clock
PB10
SCL
I2C Data
PB11
SDA
Power Supply
5V
5V
Ground
GND
GND
1

Take a closer look

Schematic

RTC 21 Click Schematic schematic

Step by step

Project assembly

Clicker 4 for STM32F4 front image hardware assembly

Start by selecting your development board and Click board™. Begin with the Clicker 4 for STM32F4 as your development board.

Clicker 4 for STM32F4 front image hardware assembly
Rotary O 2 Click front image hardware assembly
Clicker 4 STM32F4 MB 1 - upright/background hardware assembly
Necto image step 2 hardware assembly
Necto image step 3 hardware assembly
Necto image step 4 hardware assembly
Necto image step 5 hardware assembly
Necto image step 6 hardware assembly
Clicker 4 for STM32F4 HA MCU Step hardware assembly
Necto No Display image step 8 hardware assembly
Necto image step 9 hardware assembly
Necto image step 10 hardware assembly
Debug Image Necto Step hardware assembly

Track your results in real time

Application Output

After loading the code example, pressing the "DEBUG" button builds and programs it on the selected setup.

Application Output Step 1

After programming is completed, a header with buttons for various actions available in the IDE appears. By clicking the green "PLAY "button, we start reading the results achieved with Click board™.

Application Output Step 3

Upon completion of programming, the Application Output tab is automatically opened, where the achieved result can be read. In case of an inability to perform the Debug function, check if a proper connection between the MCU used by the setup and the CODEGRIP programmer has been established. A detailed explanation of the CODEGRIP-board connection can be found in the CODEGRIP User Manual. Please find it in the RESOURCES section.

Application Output Step 4

Software Support

Library Description

This library contains API for RTC 21 Click driver.

Key functions:

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

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

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

Open Source

Code example

This example can be found in NECTO Studio. Feel free to download the code, or you can copy the code below.

/*!
 * @file main.c
 * @brief RTC 21 Click 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.
 *
 * ## Application Task
 * Reads and displays on the USB UART the current time and date values once per second.
 *
 * @author Stefan Filipovic
 *
 */

#include "board.h"
#include "log.h"
#include "rtc21.h"

static rtc21_t rtc21;
static log_t logger;
static rtc21_time_t time;
static rtc21_date_t date;

/**
 * @brief RTC 21 get day of week name function.
 * @details This function returns the name of day of the week as a string.
 * @param[in] ctx : Click context object.
 * See #rtc21_t object definition for detailed explanation.
 * @param[in] day_of_week : Day of week decimal value.
 * @return Name of day as a string.
 * @note None.
 */
static uint8_t *rtc21_get_day_of_week_name ( uint8_t day_of_week );

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 " );
}

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 );
}

void main ( void ) 
{
    application_init( );

    for ( ; ; ) 
    {
        application_task( );
    }
}

static uint8_t *rtc21_get_day_of_week_name ( uint8_t day_of_week )
{
    switch ( day_of_week )
    {
        case RTC21_MONDAY:
        {
            return "Monday";
        }
        case RTC21_TUESDAY:
        {
            return "Tuesday";
        }
        case RTC21_WEDNESDAY:
        {
            return "Wednesday";
        }
        case RTC21_THURSDAY:
        {
            return "Thursday";
        }
        case RTC21_FRIDAY:
        {
            return "Friday";
        }
        case RTC21_SATURDAY:
        {
            return "Saturday";
        }
        case RTC21_SUNDAY:
        {
            return "Sunday";
        }
        default:
        {
            return "Unknown";
        }
    }
}

// ------------------------------------------------------------------------ END

Additional Support

Resources