Intermediate
30 min
0

Stay ahead of time with DS3231M and PIC24FJ256GA705

Clocking in: The secret to precise timekeeping

RTC 10 Click with PIC24FJ256GA7 Curiosity Development Board

Published Oct 20, 2023

Click board™

RTC 10 Click

Development board

PIC24FJ256GA7 Curiosity Development Board

Compiler

NECTO Studio

MCU

PIC24FJ256GA705

Ensure accurate timestamping and synchronization of data with advanced real-time clock, elevating the performance of your solution

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Hardware Overview

How does it work?

RTC 10 Click is based on the DS3231M, a low-cost, extremely accurate, I2C real-time clock (RTC) from Analog Devices. Thanks to its high integration level, it 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 dimensions of the DS3231M itself, allow it to be used in very space-constrained applications, including wearables, medical equipment, and similar. In addition to the DS3231M, RTC 10 click is equipped with the button cell battery holder compatible with the 3000TR batteryholder, suitable for 12mm Coin Cell batteries. 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. The RTC maintains seconds, minutes, hours, day, date, month, and year information. The date at the end of the month is automatically adjusted for months

with fewer than 31 days, including corrections for leap year. The clock operates in either the 24-hour or 12-hour format with an AM/PM indicator. Two programmable time-of day alarms and a 1Hz output are provided. Address and data are transferred serially through an I2C bidirectional bus. A precision temperature-compensated voltage reference and comparator circuit monitors the status of VCC to detect power failures, to provide a reset output, and to automatically switch to the backup supply when necessary. Additionally, the RST pin is monitored as a pushbutton input for generating a microprocessor reset and is routed to the RST pin on the mikroBUS™ socket. The temperature sensor, oscillator, and digital adjustment controller logic form the highly accurate time base. The controller reads the output of the on-board temperature sensor and adjusts the final 1Hz output to maintain the required accuracy. The device is trimmed at the factory to maintain a tight accuracy over the operating temperature range.

When the device is powered by VCC, the adjustment occurs once a second. When the device is powered by VBAT, the adjustment occurs once every 10s to conserve power. Adjusting the 1Hz time base less often does not affect the device’s long-term timekeeping accuracy. The device also contains an Aging Offset register that allows a constant offset (positive or negative) to be added to the factory-trimmed adjustment value. The I2C interface is accessible whenever either VCC or VBAT is at a valid level. If a microcontroller connected to the device resets because of a loss of VCC or other event, it is possible that the microcontroller and device’s I2C communications could become unsynchronized. e.g., the microcontroller resets while reading data from the device. When the microcontroller resets, the device’s I2C interface can be placed into a known state by toggling SCL until SDA is observed to be at a high level. At that point the microcontroller should pull SDA low while SCL is high, generating a START condition.

RTC 10 Click top side image
RTC 10 Click bottom side image

Features overview

Development board

PIC24FJ256GA7 Curiosity Development Board is a cost-effective, fully integrated 16-bit development platform for first-time users, makers, and those seeking a feature-rich rapid prototyping board. Designed from the ground up to take full advantage of Microchip’s MPLAB® X IDE, the board includes an integrated programmer/debugger. It requires no additional hardware, making it a perfect starting point to explore the latest low-cost and eXtreme Low Power (XLP) 16-bit PIC24FJ256GA705 family of microcontrollers. The PIC24FJ256GA7 Curiosity Board enables easy and faster adoption of low-cost

XLP 16-bit PIC24FJ256GA705 family of microcontrollers. PIC24FJ256GA705 microcontroller featuring up to 256KB of ECC flash and 16KB of RAM is ideally suited for low power general purpose applications. The layout and external connections of the PIC24FJ256GA7 Curiosity board offer unparalleled access to the Core Independent Peripherals (CIPs) such as CLC, MCCP, and DMA. These CIPs enable the user to integrate various system functions onto a single MCU, simplifying the design and keeping system power consumption, and BOM cost low. This board

can also enable applications with low power, low pin count, and small footprint requirements, as in IoT sensor nodes. Out of the box, the board offers several options for user interface—including switches, RGB LED, user LEDs, and analog potentiometers. In addition, wireless connectivity can easily be added using two mikroBUS™ interfaces and wireless connectivity Click boards™. A full complement of accessory boards is available via the MIKROE mikroBUS™ interfaces.

PIC24FJ256GA7 Curiosity double side image

Microcontroller Overview

MCU Card / MCU

default

Architecture

dsPIC

MCU Memory (KB)

256

Silicon Vendor

Microchip

Pin count

48

RAM (Bytes)

16384

Used MCU Pins

mikroBUS™ mapper

Analog ECG Output
RC1
AN
Reset
RA13
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
RC8
INT
NC
NC
TX
NC
NC
RX
I2C Clock
RB3
SCL
I2C Data
RB2
SDA
Power Supply
5V
5V
Ground
GND
GND
1

Take a closer look

Schematic

RTC 10 Click Schematic schematic

Step by step

Project assembly

PIC24FJ256GA7 Curiosity front image hardware assembly

Start by selecting your development board and Click board™. Begin with the PIC24FJ256GA7 Curiosity Development Board as your development board.

PIC24FJ256GA7 Curiosity front image hardware assembly
Thermo 28 Click front image hardware assembly
Prog-cut hardware assembly
PIC24FJ256GA7 Curiosity 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
PIC24FJ256GA7 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

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 10 Click driver.

Key functions:

  • rtc10_generic_write - Generic write function.

  • rtc10_generic_read - Generic read function.

  • rtc10_hw_reset - Hardware reset function.

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 Rtc10 Click example
 * 
 * # Description
 * This application is a real-time clock module.
 *
 * The demo application is composed of two sections :
 * 
 * ## Application Init 
 * Initialization driver enable's - I2C,
 * hardware reset, set start time and date, enable counting also, write log.
 * 
 * ## Application Task  
 * This is an example which demonstrates the use of RTC 10 Click board.
 * RTC 10 Click communicates with register via I2C interface,
 * set time and date, enable counting and display time and date values,
 * also, display temperature value for every 1 sec.
 * Results are being sent to the Usart Terminal where you can track their changes.
 * All data logs write on Usart Terminal changes for every 1 sec.
 * 
 * \author MikroE Team
 *
 */
// ------------------------------------------------------------------- INCLUDES

#include "board.h"
#include "log.h"
#include "rtc10.h"

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

static rtc10_t rtc10;
static log_t logger;

uint8_t sec_flag;

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

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

void application_init ( void )
{
    log_cfg_t log_cfg;
    rtc10_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.

    rtc10_cfg_setup( &cfg );
    RTC10_MAP_MIKROBUS( cfg, MIKROBUS_1 );
    rtc10_init( &rtc10, &cfg );

    Delay_ms( 1000 );
    
    sec_flag = 0xFF;

    log_printf( &logger, "------------------- \r\n" );
    log_printf( &logger, "  Hardware  Reset   \r\n" );
    rtc10_hw_reset(  &rtc10 );
    Delay_ms( 1000 );

    // Set Time: 23h, 59 min and 50 sec
    rtc10_set_time(  &rtc10, 23, 59, 50 );
    Delay_ms( 10 );

    // Set Date: 6 ( Day of the week: Saturday ), 31 ( day ), 8 ( month ) and 2019 ( year )
    rtc10_set_date(  &rtc10,  6, 31, 8, 2019 );
    Delay_ms( 100 );

    log_printf( &logger, "-------------------  \r\n" );
    log_printf( &logger, "  Enable Counting  \r\n" );
    log_printf( &logger, "------------------- \r\n" );
    log_printf( &logger, "     Start RTC      \r\n" );
    log_printf( &logger, "------------------- \r\n" );
    rtc10_enable_counting(  &rtc10 );
    Delay_ms( 100 );
}

void application_task ( void )
{
    uint8_t i;
    uint8_t time_hours = 0;
    uint8_t time_minutes = 0;
    uint8_t time_seconds = 0;

    uint8_t day_of_the_week = 0;
    uint8_t date_day = 0;
    uint8_t date_month = 0;
    uint8_t date_year = 0;
    
    float temperature;
    
    rtc10_get_time( &rtc10, &time_hours, &time_minutes, &time_seconds );
    Delay_ms( 100 );

    rtc10_get_date( &rtc10, &day_of_the_week, &date_day, &date_month, &date_year );
    Delay_ms( 100 );

    if ( sec_flag !=  time_seconds )
    {
        log_printf( &logger, " \r\n\n Time: %u:%u:%u  ", (uint16_t)time_hours, (uint16_t)time_minutes, (uint16_t)time_seconds );
        
        log_printf( &logger, "Date: %u. %u. 20%u. ", (uint16_t)date_day, (uint16_t)date_month, (uint16_t)date_year );
        display_day_of_the_week( day_of_the_week );
        
        if ( time_seconds == 0 )
        {
            temperature = rtc10_get_temperature( &rtc10 );

            log_printf( &logger, "\r\n\n Temp.:%.2f C", temperature);
        }
        log_printf( &logger, "--------------------------------------------" );

        sec_flag =  time_seconds;
    }
}

void main ( void )
{
    application_init( );

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

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

Additional Support

Resources