10 min

Seize every moment with BQ32000 and PIC18F47K42

Timekeeping excellence

RTC 3 Click with Curiosity HPC

Published Nov 01, 2023

Click board™

RTC 3 Click

Development board

Curiosity HPC


NECTO Studio



Incorporate a high-performance real-time clock into your solution and boost your timing control



Hardware Overview

How does it work?

RTC 3 Click is based on the BQ32000, a real-time clock from Texas Instruments presenting a compatible replacement for industry standard real-time clocks. The BQ32000 features an automatic backup supply with an integrated trickle charger for an automatic switchover to a backup power supply providing additional reliability (the circuit maintains the backup charge with an onboard supercapacitor). It also comes with a programmable calibration adjustment from –63ppm to +126ppm and clock frequency derived from an onboard 32.768KHz oscillator. The BQ32000 communicates with the MCU using the standard I2C 2-Wire interface with a maximum

frequency of 400kHz. Its time registers are updated once per second, with registers updated simultaneously to prevent a time-keeping glitch. It should be noted that when the BQ32000 switches from the main power supply to the backup supply, the time-keeping register cannot be accessed via the I2C interface. The access to these registers is only with supply voltage present. The time-keeping registers can take up to one second to update after the device switches from the backup power supply to the main power supply. The BQ32000 also includes an automatic leap year correction and general interrupt or oscillator fail flag indicating the status of the RTC oscillator

routed to the INT pin of the mikroBUS™ socket. The RTC classifies a leap year as any year evenly divisible by 4. Using this rule allows for reliable leap-year compensation until 2100. The host MCU must compensate for years that fall outside this rule. This Click board™ can be operated only with a 3.3V logic voltage level. The board must perform appropriate logic voltage level conversion before using MCUs with different logic levels. However, the Click board™ comes equipped with a library containing functions and an example code that can be used as a reference for further development.

RTC 3 Click hardware overview image

Features overview

Development board

Curiosity HPC, standing for Curiosity High Pin Count (HPC) development board, supports 28- and 40-pin 8-bit PIC MCUs specially designed by Microchip for the needs of rapid development of embedded applications. This board has two unique PDIP sockets, surrounded by dual-row expansion headers, allowing connectivity to all pins on the populated PIC MCUs. It also contains a powerful onboard PICkit™ (PKOB), eliminating the need for an external programming/debugging tool, two mikroBUS™ sockets for Click board™ connectivity, a USB connector, a set of indicator LEDs, push button switches and a variable potentiometer. All

these features allow you to combine the strength of Microchip and Mikroe and create custom electronic solutions more efficiently than ever. Each part of the Curiosity HPC development board contains the components necessary for the most efficient operation of the same board. An integrated onboard PICkit™ (PKOB) allows low-voltage programming and in-circuit debugging for all supported devices. When used with the MPLAB® X Integrated Development Environment (IDE, version 3.0 or higher) or MPLAB® Xpress IDE, in-circuit debugging allows users to run, modify, and troubleshoot their custom software and hardware

quickly without the need for additional debugging tools. Besides, it includes a clean and regulated power supply block for the development board via the USB Micro-B connector, alongside all communication methods that mikroBUS™ itself supports. Curiosity HPC development board allows you to create a new application in just a few steps. Natively supported by Microchip software tools, it covers many aspects of prototyping thanks to many number of different Click boards™ (over a thousand boards), the number of which is growing daily.

Curiosity HPC double image

Microcontroller Overview

MCU Card / MCU




MCU Memory (KB)


Silicon Vendor


Pin count


RAM (Bytes)


Used MCU Pins

mikroBUS™ mapper

Power Supply
I2C Clock
I2C Data

Take a closer look


RTC 3 Click Schematic schematic

Step by step

Project assembly

Curiosity HPC front no-mcu image hardware assembly

Start by selecting your development board and Click board™. Begin with the Curiosity HPC as your development board.

Curiosity HPC front no-mcu image hardware assembly
Thermo 28 Click front image hardware assembly
MCU DIP 40 hardware assembly
Prog-cut hardware assembly
Curiosity HPC MB 1 - upright/with-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
Necto DIP image step 7 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 3 Click driver.

Key functions:

  • rtc3_set_time - Function sets time: hours, minutes and seconds data to the target register address of PCF8583 chip on RTC 3 Click

  • rtc3_get_time - Function gets time: hours, minutes and seconds data from the target register address of PCF8583 chip on RTC 3 Click

  • rtc3_set_calibration - Function set calibration by write CAL_CFG1 register of BQ32000 chip

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 
 * \brief Rtc3 Click example
 * # Description
 * This application enables time measurment over RTC3 click.
 * The demo application is composed of two sections :
 * ## Application Init 
 * Initialization driver enable's - I2C,
 * set start time and date, enable counting and start write log.
 * ## Application Task  
 * This is a example which demonstrates the use of RTC 3 Click board.
 * RTC 3 Click communicates with register via I2C by write to register and read from register,
 * set time and date, get time and date, enable and disable counting
 * and set frequency by write configuration register.
 * Results are being sent to the Usart Terminal where you can track their changes.
 * All data logs write on usb uart changes for every 1 sec.
 * *note:* 
 * Time stats measuring correctly but from 0 seconds, after 10 seconds.
 * \author MikroE Team
// ------------------------------------------------------------------- INCLUDES

#include "board.h"
#include "log.h"
#include "rtc3.h"

// ------------------------------------------------------------------ VARIABLES

static rtc3_t rtc3;
static log_t logger;

// ------------------------------------------------------- ADDITIONAL FUNCTIONS

void display_log_day_of_the_week ( uint8_t day_of_the_week )
    if ( day_of_the_week == 1 )
        log_printf( &logger, "      Monday      \r\n" );
    if ( day_of_the_week == 2 )
        log_printf( &logger, "      Tuesday     \r\n" );
    if ( day_of_the_week == 3 )
        log_printf( &logger, "     Wednesday    \r\n" );
    if ( day_of_the_week == 4 )
        log_printf( &logger, "     Thursday     \r\n" );
    if ( day_of_the_week == 5 )
        log_printf( &logger, "      Friday      \r\n" );
    if ( day_of_the_week == 6 )
        log_printf( &logger, "     Saturday     \r\n" );
    if ( day_of_the_week == 7 )
        log_printf( &logger, "      Sunday      \r\n" );

// ------------------------------------------------------ APPLICATION FUNCTIONS

void application_init ( void )
    log_cfg_t log_cfg;
    rtc3_cfg_t cfg;

     * 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.

    rtc3_cfg_setup( &cfg );
    rtc3_init( &rtc3, &cfg );

    /// Set Time: 23h, 59 min, 50 sec

    rtc3.time.time_hours = 23;
    rtc3.time.time_minutes = 59;
    rtc3.time.time_seconds = 50;

    rtc3_set_time( &rtc3 );

    // Set Date: 1 ( Day of the week ), 31 ( day ), 12 ( month ) and 2018 ( year ) = 1; = 31; = 12; = 2018;

    rtc3_set_date( &rtc3 );

    // Start counting
    rtc3_enable_disable_counting( &rtc3, 1 );
    Delay_100ms( );
    Delay_ms( 1000 );

void application_task ( void )
    //  Task implementation.

    uint8_t time_seconds_new = 0xFF;

    rtc3_get_time( &rtc3 );

    rtc3_get_date( &rtc3 );

    if ( time_seconds_new != rtc3.time.time_seconds )
        if ( ( ( rtc3.time.time_hours | rtc3.time.time_minutes | rtc3.time.time_seconds ) == 0 )  && ( ( | ) == 1 ) )
            log_printf( &logger, "  Happy New Year  \r\n" );
            log_printf( &logger, "------------------\r\n" );

        log_printf( &logger, " Time : %d:%d:%d \r\n Date: %d.%d.20%d.\r\n------------------\r\n", (uint16_t)rtc3.time.time_hours, (uint16_t)rtc3.time.time_minutes,
                                                                                            (uint16_t), (uint16_t), (uint16_t) );

        time_seconds_new = rtc3.time.time_seconds;

    Delay_ms( 200 );

void main ( void )
    application_init( );

    for ( ; ; )
        application_task( );

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

Additional Support