30 min

Measure the passage of time with MAX31334 and PIC18F97J94

Add time management to your application

RTC 19 Click with UNI-DS v8

Published Feb 17, 2023

Click board™

RTC 19 Click

Dev Board



NECTO Studio



Keep track of time in the right way and with the right tools



Hardware Overview

How does it work?

RTC 19 Click is based on the MAX31334, an ultra-low power, real-time clock (RTC) time-keeping device from Analog Devices. The MAX31334 is configured to transmit calendar and time data to the MCU (24-hour/12-hour format) based on a 32.768kHz quartz crystal and comes with an integrated interrupt generation function. 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, days, months, year, and date information. The end-of-the-month date is automatically adjusted for months with fewer than 31 days, including corrections for the leap year. The MAX31334 features an integrated high-side power pass switch (detectable through a PSW pin and drawn to the TP1 testpoint for external use), enabling idle, ultra-low power modes on duty-cycled applications by disconnecting power to other devices on the system. The power switch ON/OFF durations can be controlled by periodic

interrupt sources such as a countdown timer, alarms, or by an external interrupt from a DIN pushbutton. The DIN signal represents a digital Schmitt trigger that records timestamps or asserts an interrupt on its falling/rising edge. In addition to the DIN button, the state of this signal can also be changed digitally using the DIN pin, routed on the RST pin of the mikroBUS socket. The selection can be performed using an onboard SMD jumper labeled DIN SEL, placing it in an appropriate position marked as MB or T, where MB stands for mikroBUS and T for the button. 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 circuitry configured to generate a time-of-day/date interrupt signal. An alarm (interrupt) signal, marked as INA and routed to the INT pin of the mikroBUS socket, allows outputting warning every day or on a specific day visually

indicated by a red LED marked as ALARM. By utilizing an automatic backup switch, when the main supply drops below the programmed threshold voltage, this RTC can use an external power source (220mF supercapacitor), allowing uninterrupted operation. Besides an automatic backup switchover circuit, this board also carries a header for additional alarm/interrupt and a programmable clock output signal for frequencies from 1Hz to 32kHz available on an onboard J1 header. In addition, this signal also exists on the AN pin of the mikroBUS socket marked with INTB. 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. However, the 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 19 Click hardware overview image

Features overview

Development board

UNI-DS v8 is a development board specially designed for the needs of rapid development of embedded applications. It supports a wide range of microcontrollers, such as different STM32, Kinetis, TIVA, CEC, MSP, PIC, dsPIC, PIC32, and AVR MCUs regardless of their number of pins, and a broad set of unique functions, such as the first-ever embedded debugger/programmer over WiFi. The development board is well organized and designed so that the end-user has all the necessary elements, such as switches, buttons, indicators, connectors, and others, in one place. Thanks to innovative manufacturing technology, UNI-DS v8 provides a fluid and immersive working experience, allowing access anywhere and under any

circumstances at any time. Each part of the UNI-DS v8 development board contains the components necessary for the most efficient operation of the same board. An advanced integrated CODEGRIP programmer/debugger module offers many valuable programming/debugging options, including support for JTAG, SWD, and SWO Trace (Single Wire Output)), and seamless integration with the Mikroe software environment. Besides, it also includes a clean and regulated power supply module for the development board. It can use a wide range of external power sources, including a battery, an external 12V power supply, and a power source via the USB Type-C (USB-C) connector. Communication options such as USB-UART, USB

HOST/DEVICE, CAN (on the MCU card, if supported), and Ethernet is also included. In addition, it also has the well-established mikroBUS™ standard, a standardized socket for the MCU card (SiBRAIN standard), and two display options for the TFT board line of products and character-based LCD. UNI-DS v8 is an integral part of the Mikroe ecosystem for rapid development. Natively supported by Mikroe software tools, it covers many aspects of prototyping and development thanks to a considerable number of different Click boards™ (over a thousand boards), the number of which is growing every day.

UNI-DS v8 horizontal image

Microcontroller Overview

MCU Card / MCU



8th Generation



MCU Memory (KB)


Silicon Vendor


Pin count


RAM (Bytes)


Used MCU Pins

mikroBUS™ mapper

Clock/Alarm Interrupt B
Schmitt Trigger
Power Supply
Power Switch
Alarm Interrupt A
I2C Clock
I2C Data
Power Supply

Take a closer look


RTC 19 Click Schematic schematic

Step by step

Project assembly

Fusion for PIC v8 front image hardware assembly

Start by selecting your development board and Click board™. Begin with the UNI-DS v8 as your development board.

Fusion for PIC v8 front image hardware assembly
Buck 22 Click front image hardware assembly
SiBRAIN for PIC32MZ1024EFK144 front image hardware assembly
v8 SiBRAIN 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 Compiler Selection Step Image hardware assembly
NECTO Output Selection Step Image hardware assembly
Necto image step 6 hardware assembly
Necto image step 7 hardware assembly
Necto image step 8 hardware assembly
Necto image step 9 hardware assembly
Necto image step 10 hardware assembly
Necto PreFlash Image hardware assembly

Track your results in real time

Application Output

After pressing the "FLASH" button on the left-side panel, it is necessary to open the UART terminal to display the achieved results. By clicking on the Tools icon in the right-hand panel, multiple different functions are displayed, among which is the UART Terminal. Click on the offered "UART Terminal" icon.

UART Application Output Step 1

Once the UART terminal is opened, the window takes on a new form. At the top of the tab are two buttons, one for adjusting the parameters of the UART terminal and the other for connecting the UART terminal. The tab's lower part is reserved for displaying the achieved results. Before connecting, the terminal has a Disconnected status, indicating that the terminal is not yet active. Before connecting, it is necessary to check the set parameters of the UART terminal. Click on the "OPTIONS" button.

UART Application Output Step 2

In the newly opened UART Terminal Options field, we check if the terminal settings are correct, such as the set port and the Baud rate of UART communication. If the data is not displayed properly, it is possible that the Baud rate value is not set correctly and needs to be adjusted to 115200. If all the parameters are set correctly, click on "CONFIGURE".

UART Application Output Step 3

The next step is to click on the "CONNECT" button, after which the terminal status changes from Disconnected to Connected in green, and the data is displayed in the Received data field.

UART Application Output Step 4

Software Support

Library Description

This library contains API for RTC 19 Click driver.

Key functions:

  • rtc19_set_time This function sets the starting time values - second, minute and hour.

  • rtc19_read_time This function reads the current time values - second, minute and hour.

  • rtc19_read_date This function reads the current date values - day of week, day, month and year.

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 19 Click example
 * # Description
 * This example demonstrates the use of RTC 19 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 resets the device and sets the timer interrupt to 1 Hz. 
 * After that, it sets the starting time and date.
 * ## Application Task
 * Waits for a timer countdown interrupt (1 Hz) and then reads and displays on the USB UART 
 * the current time and date values.
 * @author Stefan Filipovic

#include "board.h"
#include "log.h"
#include "rtc19.h"

static rtc19_t rtc19;
static log_t logger;
static rtc19_time_t time;
static rtc19_date_t date;

 * @brief RTC 19 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 #rtc19_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 *rtc19_get_day_of_week_name ( uint8_t day_of_week );

void application_init ( void ) 
    log_cfg_t log_cfg;  /**< Logger config object. */
    rtc19_cfg_t rtc19_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.
    rtc19_cfg_setup( &rtc19_cfg );
    RTC19_MAP_MIKROBUS( rtc19_cfg, MIKROBUS_1 );
    if ( I2C_MASTER_ERROR == rtc19_init( &rtc19, &rtc19_cfg ) ) 
        log_error( &logger, " Communication init." );
        for ( ; ; );
    if ( RTC19_ERROR == rtc19_default_cfg ( &rtc19 ) )
        log_error( &logger, " Default configuration." );
        for ( ; ; );
    time.hour = 23;
    time.minute = 59;
    time.second = 50;
    if ( RTC19_OK == rtc19_set_time ( &rtc19, &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 = RTC19_SATURDAY; = 31;
    date.month = 12;
    date.year = 22;
    if ( RTC19_OK == rtc19_set_date ( &rtc19, &date ) )
        log_printf( &logger, " Set date: %s, %.2u.%.2u.20%.2u.\r\n", 
                    rtc19_get_day_of_week_name ( date.day_of_week ),
                    ( uint16_t ), ( uint16_t ) date.month, ( uint16_t ) date.year );
    log_info( &logger, " Application Task " );

void application_task ( void ) 
    // Wait for a timer countdown flag configured at 1 Hz
    while ( rtc19_get_inta_pin ( &rtc19 ) );

    Delay_ms ( 100 );
    rtc19_clear_interrupts ( &rtc19 );
    if ( RTC19_OK == rtc19_read_time ( &rtc19, &time ) )
        log_printf( &logger, " Time: %.2u:%.2u:%.2u\r\n", 
                    ( uint16_t ) time.hour, ( uint16_t ) time.minute, ( uint16_t ) time.second );
    if ( RTC19_OK == rtc19_read_date ( &rtc19, &date ) )
        log_printf( &logger, " Date: %s, %.2u.%.2u.20%.2u.\r\n", 
                    rtc19_get_day_of_week_name ( date.day_of_week ),
                    ( uint16_t ), ( uint16_t ) date.month, ( uint16_t ) date.year );

void main ( void ) 
    application_init( );

    for ( ; ; ) 
        application_task( );

static char *rtc19_get_day_of_week_name ( uint8_t day_of_week )
    switch ( day_of_week )
        case RTC19_MONDAY:
            return "Monday";
        case RTC19_TUESDAY:
            return "Tuesday";
        case RTC19_WEDNESDAY:
            return "Wednesday";
        case RTC19_THURSDAY:
            return "Thursday";
        case RTC19_FRIDAY:
            return "Friday";
        case RTC19_SATURDAY:
            return "Saturday";
        case RTC19_SUNDAY:
            return "Sunday";
            return "Unknown";

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

Additional Support