Intermediate
30 min

Elevate your projects with RTC feature through RV5C387A and ATmega2560

The clock that never stops ticking: Meet our RTC marvel!

RTC 17 Click with Arduino Mega 2560 Rev3

Published Feb 14, 2024

Click board™

RTC 17 Click

Dev Board

Arduino Mega 2560 Rev3

Compiler

NECTO Studio

MCU

ATmega2560

Experience seamless synchronization of time-sensitive operations with high-precision real-time clock solution

A

A

Hardware Overview

How does it work?

RTC 17 Click is based on the RV5C387A, an I2C configurable real-time clock/calendar optimized for low-power operations from Nisshinbo Micro Devices. The RV5C387A is configured to transmit calendar and time data to the MCU and comes with an integrated interrupt generation function. It reads and writes time data from and to the MCU in units ranging from seconds to the last two digits of the calendar year. The calendar year will automatically be identified as a leap year when its last two digits are a multiple of 4. Consequently, leap years up to the year 2099 can automatically be recognized. 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 an alarm circuit configured to generate an interrupt signal to the INT pin of the mikroBUS™ socket from its A, B, or C interrupt pin at preset times. The alarm circuit allows two alarm settings specified by the Alarm_W and the Alarm_D registers. The Alarm_W registers (interrupt B) allow a week, hour, and minute alarm settings, including combinations of multiple day-of-week settings such as Monday and Wednesday, while the Alarm_D registers (interrupt C) allow an hour and minute alarm settings. Besides, the RV5C387A can generate periodic interrupt signals aside from interrupt signals generated by the alarm circuit from the interrupt A pin. The RTC 17 Click also has an onboard header labeled CLKO, which provides clock pulses of 32kHz. Like this

one, the most common RTC configuration is a battery-backed-up, which maintains time and continues its work without interruption in the event of a power failure. That’s why, besides the BU9873, the RTC 17 Click is equipped with a button cell battery holder compatible with the 3000TR battery holder, suitable for 12mm Coin Cell batteries. 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 as a reference for further development.

RTC 17 Click hardware overview image

Features overview

Development board

Arduino Mega 2560 is a robust microcontroller platform built around the ATmega 2560 chip. It has extensive capabilities and boasts 54 digital input/output pins, including 15 PWM outputs, 16 analog inputs, and 4 UARTs. With a 16MHz crystal

oscillator ensuring precise timing, it offers seamless connectivity via USB, a convenient power jack, an ICSP header, and a reset button. This all-inclusive board simplifies microcontroller projects; connect it to your computer via USB or power it up

using an AC-to-DC adapter or battery. Notably, the Mega 2560 maintains compatibility with a wide range of shields crafted for the Uno, Duemilanove, or Diecimila boards, ensuring versatility and ease of integration.

Arduino Mega 2560 Rev3 double side image

Microcontroller Overview

MCU Card / MCU

default

Architecture

AVR

MCU Memory (KB)

256

Silicon Vendor

Microchip

Pin count

100

RAM (Bytes)

8192

You complete me!

Accessories

Click Shield for Arduino Mega comes equipped with four mikroBUS™ sockets, with two in the form of a Shuttle connector, allowing all the Click board™ devices to be interfaced with the Arduino Mega board with no effort. Featuring an AVR 8-bit microcontroller with advanced RISC architecture, 54 digital I/O pins, and Arduino™ compatibility, the Arduino Mega board offers limitless possibilities for prototyping and creating diverse applications. This board is controlled and powered conveniently through a USB connection to program and debug the Arduino Mega board efficiently out of the box, with an additional USB cable connected to the USB B port on the board. Simplify your project development with the integrated ATmega16U2 programmer and unleash creativity using the extensive I/O options and expansion capabilities. There are eight switches, which you can use as inputs, and eight LEDs, which can be used as outputs of the MEGA2560. In addition, the shield features the MCP1501, a high-precision buffered voltage reference from Microchip. This reference is selected by default over the EXT REF jumper at the bottom of the board. You can choose an external one, as you would usually do with an Arduino Mega board. There is also a GND hook for testing purposes. Four additional LEDs are PWR, LED (standard pin D13), RX, and TX LEDs connected to UART1 (mikroBUS™ 1 socket). This Click Shield also has several switches that perform functions such as selecting the logic levels of analog signals on mikroBUS™ sockets and selecting logic voltage levels of the mikroBUS™ sockets themselves. Besides, the user is offered the possibility of using any Click board™ with the help of existing bidirectional level-shifting voltage translators, regardless of whether the Click board™ operates at a 3.3V or 5V logic voltage level. Once you connect the Arduino Mega board with Click Shield for Arduino Mega, you can access hundreds of Click boards™, working with 3.3V or 5V logic voltage levels.

Click Shield for Arduino Mega accessories 1 image

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
Interrupt
PB6
INT
NC
NC
TX
NC
NC
RX
I2C Clock
PD0
SCL
I2C Data
PD1
SDA
Power Supply
5V
5V
Ground
GND
GND
1

Take a closer look

Click board™ Schematic

RTC 17 Click Schematic schematic

Step by step

Project assembly

Click Shield for Arduino Mega front image hardware assembly

Start by selecting your development board and Click board™. Begin with the Arduino Mega 2560 Rev3 as your development board.

Click Shield for Arduino Mega front image hardware assembly
Arduino Mega 2560 Rev3 front image hardware assembly
Barometer 13 Click front image hardware assembly
Prog-cut hardware assembly
Arduino Mega 2560 Rev3 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
Arduino MEGA 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 via Debug Mode

1. Once the code example is loaded, pressing the "DEBUG" button initiates the build process, programs it on the created setup, and enters Debug mode.

2. After the programming is completed, a header with buttons for various actions within the IDE becomes visible. Clicking the green "PLAY" button starts reading the results achieved with the Click board™. The achieved results are displayed in the Application Output tab.

DEBUG_Application_Output

Software Support

Library Description

This library contains API for RTC 17 Click driver.

Key functions:

  • rtc17_set_time - This function sets the starting time values - second, minute and hour

  • rtc17_read_time - This function reads the current time values - second, minute and hour

  • rtc17_read_date - This function reads the current date values - day of week, day, month and year

Open Source

Code example

The complete application code and a ready-to-use project are available through the NECTO Studio Package Manager for direct installation in the NECTO Studio. The application code can also be found on the MIKROE GitHub account.

/*!
 * @file main.c
 * @brief RTC17 Click example
 *
 * # Description
 * This example demonstrates the use of RTC 17 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 performs the click default configuration
 * which sets 24h time mode and interrupt to be synchronized with second count-up.
 * And after that setting the starting time and date.
 *
 * ## Application Task
 * Waits for the second count-up interrupt and then reads and displays the current
 * time and date values on the USB UART.
 *
 * @author Stefan Filipovic
 *
 */

#include "board.h"
#include "log.h"
#include "rtc17.h"

static rtc17_t rtc17;
static log_t logger;
static rtc17_time_t time;
static rtc17_date_t date;

/**
 * @brief RTC 17 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 #rtc17_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 char *rtc17_get_day_of_week_name ( uint8_t day_of_week );

void application_init ( void ) 
{
    log_cfg_t log_cfg;  /**< Logger config object. */
    rtc17_cfg_t rtc17_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.
    rtc17_cfg_setup( &rtc17_cfg );
    RTC17_MAP_MIKROBUS( rtc17_cfg, MIKROBUS_1 );
    if ( I2C_MASTER_ERROR == rtc17_init( &rtc17, &rtc17_cfg ) ) 
    {
        log_error( &logger, " Communication init." );
        for ( ; ; );
    }
    
    if ( RTC17_ERROR == rtc17_default_cfg ( &rtc17 ) )
    {
        log_error( &logger, " Default configuration." );
        for ( ; ; );
    }
    
    time.hour = 23;
    time.minute = 59;
    time.second = 50;
    if ( RTC17_OK == rtc17_set_time ( &rtc17, &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 = RTC17_SATURDAY;
    date.day = 31;
    date.month = 12;
    date.year = 22;
    if ( RTC17_OK == rtc17_set_date ( &rtc17, &date ) )
    {
        log_printf( &logger, " Set date: %s, %.2u.%.2u.20%.2u.\r\n", 
                    rtc17_get_day_of_week_name ( date.day_of_week ),
                    ( uint16_t ) date.day, ( uint16_t ) date.month, ( uint16_t ) date.year );
    }
    
    
    log_info( &logger, " Application Task " );
}

void application_task ( void ) 
{
    // Wait for interrupt which is synchronized with second count-up
    while ( rtc17_get_int_pin ( &rtc17 ) );
    
    rtc17_clear_interrupts ( &rtc17 );
    if ( RTC17_OK == rtc17_read_time ( &rtc17, &time ) )
    {
        log_printf( &logger, " Time: %.2u:%.2u:%.2u\r\n", 
                    ( uint16_t ) time.hour, ( uint16_t ) time.minute, ( uint16_t ) time.second );
    }
    if ( RTC17_OK == rtc17_read_date ( &rtc17, &date ) )
    {
        log_printf( &logger, " Date: %s, %.2u.%.2u.20%.2u.\r\n\n", 
                    rtc17_get_day_of_week_name ( date.day_of_week ),
                    ( uint16_t ) date.day, ( uint16_t ) date.month, ( uint16_t ) date.year );
    }
}

void main ( void ) 
{
    application_init( );

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

static char *rtc17_get_day_of_week_name ( uint8_t day_of_week )
{
    switch ( day_of_week )
    {
        case RTC17_MONDAY:
        {
            return "Monday";
        }
        case RTC17_TUESDAY:
        {
            return "Tuesday";
        }
        case RTC17_WEDNESDAY:
        {
            return "Wednesday";
        }
        case RTC17_THURSDAY:
        {
            return "Thursday";
        }
        case RTC17_FRIDAY:
        {
            return "Friday";
        }
        case RTC17_SATURDAY:
        {
            return "Saturday";
        }
        case RTC17_SUNDAY:
        {
            return "Sunday";
        }
        default:
        {
            return "Unknown";
        }
    }
}

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

Additional Support

Resources

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