Stay ahead of time with DS3231M and STM32F446RE
Clocking in: The secret to precise timekeeping
Published Oct 08, 2024
Click board™
RTC 10 Click
Dev Board
Nucleo 64 with STM32F446RE MCU
Compiler
NECTO Studio
MCU
STM32F446RE
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.
Features overview
Development board
Nucleo-64 with STM32F446RE MCU offers a cost-effective and adaptable platform for developers to explore new ideas and prototype their designs. This board harnesses the versatility of the STM32 microcontroller, enabling users to select the optimal balance of performance and power consumption for their projects. It accommodates the STM32 microcontroller in the LQFP64 package and includes essential components such as a user LED, which doubles as an ARDUINO® signal, alongside user and reset push-buttons, and a 32.768kHz crystal oscillator for precise timing operations. Designed with expansion and flexibility in mind, the Nucleo-64 board features an ARDUINO® Uno V3 expansion connector and ST morpho extension pin
headers, granting complete access to the STM32's I/Os for comprehensive project integration. Power supply options are adaptable, supporting ST-LINK USB VBUS or external power sources, ensuring adaptability in various development environments. The board also has an on-board ST-LINK debugger/programmer with USB re-enumeration capability, simplifying the programming and debugging process. Moreover, the board is designed to simplify advanced development with its external SMPS for efficient Vcore logic supply, support for USB Device full speed or USB SNK/UFP full speed, and built-in cryptographic features, enhancing both the power efficiency and security of projects. Additional connectivity is
provided through dedicated connectors for external SMPS experimentation, a USB connector for the ST-LINK, and a MIPI® debug connector, expanding the possibilities for hardware interfacing and experimentation. Developers will find extensive support through comprehensive free software libraries and examples, courtesy of the STM32Cube MCU Package. This, combined with compatibility with a wide array of Integrated Development Environments (IDEs), including IAR Embedded Workbench®, MDK-ARM, and STM32CubeIDE, ensures a smooth and efficient development experience, allowing users to fully leverage the capabilities of the Nucleo-64 board in their projects.
Microcontroller Overview
MCU Card / MCU
Architecture
ARM Cortex-M4
MCU Memory (KB)
512
Silicon Vendor
STMicroelectronics
Pin count
64
RAM (Bytes)
131072
You complete me!
Accessories
Click Shield for Nucleo-64 comes equipped with two proprietary mikroBUS™ sockets, allowing all the Click board™ devices to be interfaced with the STM32 Nucleo-64 board with no effort. This way, Mikroe allows its users to add any functionality from our ever-growing range of Click boards™, such as WiFi, GSM, GPS, Bluetooth, ZigBee, environmental sensors, LEDs, speech recognition, motor control, movement sensors, and many more. More than 1537 Click boards™, which can be stacked and integrated, are at your disposal. The STM32 Nucleo-64 boards are based on the microcontrollers in 64-pin packages, a 32-bit MCU with an ARM Cortex M4 processor operating at 84MHz, 512Kb Flash, and 96KB SRAM, divided into two regions where the top section represents the ST-Link/V2 debugger and programmer while the bottom section of the board is an actual development board. These boards are controlled and powered conveniently through a USB connection to program and efficiently debug the Nucleo-64 board out of the box, with an additional USB cable connected to the USB mini port on the board. Most of the STM32 microcontroller pins are brought to the IO pins on the left and right edge of the board, which are then connected to two existing mikroBUS™ sockets. 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 STM32 Nucleo-64 board with our Click Shield for Nucleo-64, you can access hundreds of Click boards™, working with 3.3V or 5V logic voltage levels.
Used MCU Pins
mikroBUS™ mapper
Take a closer look
Click board™ Schematic
Step by step
Project assembly
Start by selecting your development board and Click board™. Begin with the Nucleo 64 with STM32F446RE MCU as your development board.
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.
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
