Intermediate
30 min

Transform your time management with MAX31341B and PIC18F57Q43

Tick-tock, seize the day

RTC 7 Click with Curiosity Nano with PIC18F57Q43

Published Feb 13, 2024

Click board™

RTC 7 Click

Dev. board

Curiosity Nano with PIC18F57Q43

Compiler

NECTO Studio

MCU

PIC18F57Q43

Experience the power of precise timekeeping in your engineering projects by integrating state-of-the-art real-time clock solution

A

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Hardware Overview

How does it work?

RTC 7 Click is based on the MAX31341B, a low-current Real-Time Clock with I2C interface and power management from Analog Devices. Thanks to its high integration level, this module provides high time accuracy, with a very low count of external components required. It has a full RTC function, offering programmable counters, alarms, and an interrupt engine with selectable event reporting sources. The small dimension of the MAX31341B module itself, allow it to be used in very space-constrained applications, including wearables, medical equipment, and similar. In addition to the MAX31341B, RTC 7 click is equipped with the 220mF super capacitor. By utilizing an automatic backup switch, the IC is able to use an external battery power source when there is no power supply on its main power terminals, thus allowing for uninterrupted operation. Draining as low as 180nA of current, it can be operated with the mentioned supercapacitor almost indefinitely.

In addition, a trickle charge system will replenish the super capacitor while the MAX31341B is powered over the main power terminals (VDD, VSS). The voltage of the main power supply can range between 1.6V up to 3.6V. The MAX31341B uses the I2C communication protocol for the communication with the host MCU. Besides the I2C bus lines, two additional pins are also available on the MAX31341B, INTA and INTB, allowing an interrupt to be reported to the host MCU, but also to capture an external event and marking it with an automatic timestamp. The two mentioned interrupt pins are routed to INT and AN pins of the mikroBUS™ socket, respectively. The user is able to set up standard clock and calendar functions (including seconds, minutes, hours, weekdays, date, months, years with leap year correction), as well as the interrupt functions for the periodic countdown timer, periodic time update, alarm, external event, automatic backup switchover and

power on reset (POR) events. All these features are available when the module is operated over the backup power supply (battery). Besides other functions, RTC 7 click have one analog and one digitital external input, labeled AIN and DIN. These universal inputs can be wired to any kind of external trigger, which needs to trigger one of the interrupts. The digital input can be configured to detect rising or falling edge, while the analog input, besides the edge detection, supports the programmable threshold too. For detailed information on interrupts and external triggers, refer to the MAX31341B datasheet. 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. Also, it comes equipped with a library containing functions and an example code that can be used as a reference for further development.

RTC 7 Click top side image
RTC 7 Click bottom side image

Features overview

Development board

PIC18F57Q43 Curiosity Nano evaluation kit is a cutting-edge hardware platform designed to evaluate microcontrollers within the PIC18-Q43 family. Central to its design is the inclusion of the powerful PIC18F57Q43 microcontroller (MCU), offering advanced functionalities and robust performance. Key features of this evaluation kit include a yellow user LED and a responsive

mechanical user switch, providing seamless interaction and testing. The provision for a 32.768kHz crystal footprint ensures precision timing capabilities. With an onboard debugger boasting a green power and status LED, programming and debugging become intuitive and efficient. Further enhancing its utility is the Virtual serial port (CDC) and a debug GPIO channel (DGI

GPIO), offering extensive connectivity options. Powered via USB, this kit boasts an adjustable target voltage feature facilitated by the MIC5353 LDO regulator, ensuring stable operation with an output voltage ranging from 1.8V to 5.1V, with a maximum output current of 500mA, subject to ambient temperature and voltage constraints.

PIC18F57Q43 Curiosity Nano double side image

Microcontroller Overview

MCU Card / MCU

default

Architecture

PIC

MCU Memory (KB)

128

Silicon Vendor

Microchip

Pin count

48

RAM (Bytes)

8196

You complete me!

Accessories

Curiosity Nano Base for Click boards is a versatile hardware extension platform created to streamline the integration between Curiosity Nano kits and extension boards, tailored explicitly for the mikroBUS™-standardized Click boards and Xplained Pro extension boards. This innovative base board (shield) offers seamless connectivity and expansion possibilities, simplifying experimentation and development. Key features include USB power compatibility from the Curiosity Nano kit, alongside an alternative external power input option for enhanced flexibility. The onboard Li-Ion/LiPo charger and management circuit ensure smooth operation for battery-powered applications, simplifying usage and management. Moreover, the base incorporates a fixed 3.3V PSU dedicated to target and mikroBUS™ power rails, alongside a fixed 5.0V boost converter catering to 5V power rails of mikroBUS™ sockets, providing stable power delivery for various connected devices.

Curiosity Nano Base for Click boards accessories 1 image

Used MCU Pins

mikroBUS™ mapper

Interrupt B
PA0
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 A
PA6
INT
NC
NC
TX
NC
NC
RX
I2C Clock
PB2
SCL
I2C Data
PB1
SDA
NC
NC
5V
Ground
GND
GND
1

Take a closer look

Click board™ Schematic

RTC 7 Click Schematic schematic

Step by step

Project assembly

Curiosity Nano Base for Click boards front image hardware assembly

Start by selecting your development board and Click board™. Begin with the Curiosity Nano with PIC18F57Q43 as your development board.

Curiosity Nano Base for Click boards front image hardware assembly
Charger 27 Click front image hardware assembly
PIC18F47Q10 Curiosity Nano front image hardware assembly
Prog-cut hardware assembly
Charger 27 Click complete accessories setup image hardware assembly
Board mapper by product8 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
PIC18F57Q43 Curiosity 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

1. Application Output - In Debug mode, the 'Application Output' window enables real-time data monitoring, offering direct insight into execution results. Ensure proper data display by configuring the environment correctly using the provided tutorial.

2. UART Terminal - Use the UART Terminal to monitor data transmission via a USB to UART converter, allowing direct communication between the Click board™ and your development system. Configure the baud rate and other serial settings according to your project's requirements to ensure proper functionality. For step-by-step setup instructions, refer to the provided tutorial.

3. Plot Output - The Plot feature offers a powerful way to visualize real-time sensor data, enabling trend analysis, debugging, and comparison of multiple data points. To set it up correctly, follow the provided tutorial, which includes a step-by-step example of using the Plot feature to display Click board™ readings. To use the Plot feature in your code, use the function: plot(*insert_graph_name*, variable_name);. This is a general format, and it is up to the user to replace 'insert_graph_name' with the actual graph name and 'variable_name' with the parameter to be displayed.

Software Support

Library Description

This library contains API for RTC 7 Click driver.

Key functions:

  • rtc7_check_interrupt - This function returns the interrupt state, state of INTA pin

  • rtc7_read_reg - This function writes one byte data to the register

  • rtc7_get_local_time - This function gets the local time data including the determined time zone in calculations

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 
 * \brief RTC7 Click example
 * 
 * # Description
 * This app is used to accurately measure time with low power consumption.
 *
 * The demo application is composed of two sections :
 * 
 * ## Application Init 
 * Initializes device.
 * 
 * ## Application Task  
 * Waits for a second count-up interrupt and then reads and logs the current
 * time and date on the USB UART.
 * 
 * \author MikroE Team
 *
 */
// ------------------------------------------------------------------- INCLUDES

#include "board.h"
#include "log.h"
#include "rtc7.h"

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

static rtc7_t rtc7;
static log_t logger;

rtc7_time_t time_set;
rtc7_time_t time_date;

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

void rtc7_display_results ( rtc7_t *ctx )
{
    log_printf( &logger, " %.2u:%.2u:%.2u\r\n", 
                ( uint16_t ) time_date.hours, ( uint16_t ) time_date.minutes, ( uint16_t ) time_date.seconds );

    log_printf( &logger, " %.2u/%.2u/%.2u ", 
                ( uint16_t ) time_date.monthday, ( uint16_t ) time_date.month, ( uint16_t ) time_date.year );
    switch ( time_date.weekdays )
    {
        case 1:
        {
            log_printf( &logger, "MONDAY" );
            break;
        }
        case 2:
        {
            log_printf( &logger, "TUESDAY" );
            break;
        }
        case 3:
        {
            log_printf( &logger, "WEDNESDAY" );
            break;
        }
        case 4:
        {
            log_printf( &logger, "THURSDAY" );
            break;
        }
        case 5:
        {
            log_printf( &logger, "FRIDAY" );
            break;
        }
        case 6:
        {
            log_printf( &logger, "SATURDAY" );
            break;
        }
        case 7:
        {
            log_printf( &logger, "SUNDAY" );
            break;
        }
        default:
        {
            break;
        }
    }
    log_printf( &logger, "\r\n-------------------\r\n" );
}

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

void application_init ( void )
{
    log_cfg_t log_cfg;
    rtc7_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.
    rtc7_cfg_setup( &cfg );
    RTC7_MAP_MIKROBUS( cfg, MIKROBUS_1 );
    rtc7_init( &rtc7, &cfg );
    Delay_ms ( 300 );
    
    time_set.seconds = 40;
    time_set.minutes = 59;
    time_set.hours = 23;
    time_set.weekdays = 1;
    time_set.monthday = 31;
    time_set.month = 12;
    time_set.year = 22;
    
    err_t error_flag = rtc7_reset( &rtc7 );
    error_flag |= rtc7_init_time ( &rtc7, 0 );
    error_flag |= rtc7_set_gmt_time( &rtc7, &time_set );
    error_flag |= rtc7_set_osc( &rtc7, RTC7_ENABLE_OSC, RTC7_INPUT_FREQ_32768HZ, RTC7_OUTPUT_FREQ_32768HZ );
    error_flag |= rtc7_write_reg( &rtc7, RTC7_TIMER_INIT_REG, 15 );
    error_flag |= rtc7_set_timer( &rtc7, RTC7_TIMER_EN, RTC7_TIMER_FREQ_16HZ );
    Delay_ms ( 100 );
    if ( RTC7_ERROR == error_flag )
    {
        log_error( &logger, " Default configuration." );
        for ( ; ; );
    }
    log_info( &logger, " Application Task " );
}

void application_task ( void )
{
    // Wait for timer count-down interrupt which is set to 1Hz
    while ( rtc7_check_interrupt ( &rtc7 ) );

    // Clear interrupt status
    uint8_t int_status = 0;
    rtc7_read_reg( &rtc7, RTC7_INT_STATUS_REG, &int_status, 1 );
    
    // Read time
    if ( RTC7_OK == rtc7_get_local_time( &rtc7, &time_date ) )
    {
        // Display time
        rtc7_display_results( &rtc7 );
    }
}

int main ( void ) 
{
    /* Do not remove this line or clock might not be set correctly. */
    #ifdef PREINIT_SUPPORTED
    preinit();
    #endif
    
    application_init( );
    
    for ( ; ; ) 
    {
        application_task( );
    }

    return 0;
}

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

Additional Support

Resources

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