Intermediate
30 min

Always be on time with AB0815 and STM32L073RZ

RTC: Your silent reminder in a noisy world

RTC 11 Click with Nucleo-64 with STM32L073RZ MCU

Published Feb 26, 2024

Click board™

RTC 11 Click

Dev Board

Nucleo-64 with STM32L073RZ MCU

Compiler

NECTO Studio

MCU

STM32L073RZ

Integrate reliable real-time clock into your solution to enable precise event sequencing and accurate time measurement

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Hardware Overview

How does it work?

RTC 11 Click is based on the AB0815, an ultra-low-power coupled with a highly sophisticated feature set, the real-time clock from Abracon. The AB0815 is a full-function RTC and includes three feature groups: baseline and advanced timekeeping features and power management. Functions from each feature group may be controlled via I/O offset mapped registers accessed through the SPI serial interface. The baseline timekeeping feature group supports the standard 32.786 kHz crystal oscillation mode for maximum frequency accuracy with an ultra-low current draw of 22nA. This feature includes standard counters for minutes, hours, dates, months, years, and weekdays. A complement of countdown timers and alarms may additionally be set to initiate interrupts or

resets on several outputs. The most common configuration on this Click board™ is a battery-backed-up RTC, which maintains time and may hold data in RAM. In addition to the AB0815, the RTC 11 Click is equipped with a button cell battery holder compatible with the 3000TR battery holder, suitable for 12mm Coin Cell batteries. By utilizing an automatic backup switch, the AB0815 can use an external battery power source when there is no power supply on its main power terminals, thus allowing for uninterrupted operation. The AB0815 communicates with MCU using the standard SPI serial interface that supports modes 0 and 3 with a maximum frequency of 2 MHz. The flexible inputs of the AB0815 can be used to aggregate various interrupt sources, including external digital inputs,

analog levels, timers, and alarms, into a single interrupt source to an MCU. Based on this, functions like external interrupt or watchdog timer reset could be found on this Click board™ routed on the RST and AN pins of the mikroBUS™ socket labeled as EXI and WDI, as well as the primary and secondary interrupt outputs routed on the INT and PWM pins of the mikroBUS™ socket labeled as IT1 and IT2. 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 11 Click top side image
RTC 11 Click bottom side image

Features overview

Development board

Nucleo-64 with STM32L073RZ 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.

Nucleo 64 with STM32L073RZ MCU double side image

Microcontroller Overview

MCU Card / MCU

default

Architecture

ARM Cortex-M0

MCU Memory (KB)

192

Silicon Vendor

STMicroelectronics

Pin count

64

RAM (Bytes)

20480

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.

Click Shield for Nucleo-64 accessories 1 image

Used MCU Pins

mikroBUS™ mapper

Watchdog Timer Reset
PC0
AN
External Interrupt
PC12
RST
SPI Chip Select
PB12
CS
SPI Clock
PB3
SCK
SPI Data OUT
PB4
MISO
SPI Data IN
PB5
MOSI
Power Supply
3.3V
3.3V
Ground
GND
GND
Secondary Interrupt
PC8
PWM
Primary Interrupt
PC14
INT
NC
NC
TX
NC
NC
RX
NC
NC
SCL
NC
NC
SDA
NC
NC
5V
Ground
GND
GND
1

Take a closer look

Schematic

RTC 11 Click Schematic schematic

Step by step

Project assembly

Click Shield for Nucleo-64 front image hardware assembly

Start by selecting your development board and Click board™. Begin with the Nucleo-64 with STM32L073RZ MCU as your development board.

Click Shield for Nucleo-64 front image hardware assembly
Nucleo 64 with STM32F401RE MCU front image hardware assembly
EEPROM 13 Click front image hardware assembly
Prog-cut hardware assembly
Nucleo-64 with STM32XXX MCU MB 1 Mini B Conn - 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
Clicker 4 for STM32F4 HA 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 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.

DEBUG_Application_Output

Software Support

Library Description

This library contains API for RTC 11 Click driver.

Key functions:

  • rtc11_set_time - Set time hours, minutes and seconds function

  • rtc11_get_time - Get time hours, minutes and seconds function

  • rtc11_set_date - Set date day of the week, day, month and year 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 main.c
 * @brief RTC11 Click example
 *
 * # Description
 * This is an example that demonstrates the use of the RTC 11 click board™.
 *
 * The demo application is composed of two sections :
 *
 * ## Application Init
 * Initalizes SPI, performs software reset, sets 
 * system time and date, and starts clocking system.
 *
 * ## Application Task
 * Demonstrates use of RTC 11 click board by reading and
 * displaying time and date via USART terminal.
 * 
 * Additional Functions :
 * 
 * void disp_day_of_the_week ( uint8_t w_day ) - Writes the day of the week on 
 * USART terminal.
 *
 * @author Stefan Ilic
 *
 */

#include "board.h"
#include "log.h"
#include "rtc11.h"

static rtc11_t rtc11;
static log_t logger;

static rtc11_time_t time;
static rtc11_date_t date;

uint8_t sec_flag = 0xFF;

void disp_day_of_the_week ( uint8_t w_day ) {
    switch ( w_day )
    {
        case 0 :
        {
            log_printf( &logger, "Monday" );
            break;
        }
        case 1 :
        {
            log_printf( &logger, "Tuesday" );
            break;
        }
        case 2 :
        {
            log_printf( &logger, "Wednesday" );
            break;
        }
        case 3 :
        {
            log_printf( &logger, "Thursday" );
            break;
        }
        case 4 :
        {
            log_printf( &logger, "Friday" );
            break;
        }
        case 5 :
        {
            log_printf( &logger, "Saturday" );
            break;
        }
        case 6 :
        {
            log_printf( &logger, "Sunday" );
            break;
        }
        default :
        {
        break;
        }
    }
}
void application_init ( void ) {
    log_cfg_t log_cfg;  /**< Logger config object. */
    rtc11_cfg_t rtc11_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.

    rtc11_cfg_setup( &rtc11_cfg );
    RTC11_MAP_MIKROBUS( rtc11_cfg, MIKROBUS_1 );
    err_t init_flag  = rtc11_init( &rtc11, &rtc11_cfg );
    if ( SPI_MASTER_ERROR == init_flag ) {
        log_error( &logger, " Application Init Error. " );
        log_info( &logger, " Please, run program again... " );

        for ( ; ; );
    }
    log_printf( &logger,"------------------------\r\n" );
    log_printf( &logger," Software reset \r\n" );
    rtc11_soft_rst( &rtc11 );
    Delay_ms( 100 );
    
    time.hours = 23;
    time.min = 59;
    time.sec = 55;
    log_printf( &logger,"------------------------\r\n" );
    log_printf( &logger," Setting time: %.2d:%.2d:%.2d \r\n", ( uint16_t ) time.hours, ( uint16_t ) time.min, ( uint16_t ) time.sec );
    rtc11_set_time ( &rtc11, time );
    Delay_ms( 100 );
    
    date.day_of_week = 0;
    date.day = 19;
    date.month = 7;
    date.year = 21;
    log_printf( &logger,"------------------------\r\n" );
    log_printf( &logger," Setting date: %.2d/%.2d/%.2d \r\n", ( uint16_t ) date.day, ( uint16_t ) date.month, ( uint16_t ) date.year );
    rtc11_set_date( &rtc11, date );
    Delay_ms( 100 );
    
    rtc11_stp_sys_slk ( &rtc11, RTC11_PROP_DIS );
    log_info( &logger, " Application Task " );
    log_printf( &logger,"------------------------\r\n" );
}

void application_task ( void ) {
    rtc11_get_time ( &rtc11, &time );
    Delay_ms( 10 );
    rtc11_get_date ( &rtc11, &date );
    Delay_ms( 10 );
    
    if ( sec_flag != time.sec ) {
        log_printf( &logger, " Date: " );
        disp_day_of_the_week( date.day_of_week );
        log_printf( &logger, " %.2d/%.2d/20%.2d \r\n", ( uint16_t ) date.day, ( uint16_t ) date.month, ( uint16_t ) date.year );
        log_printf( &logger, " Time: %.2d:%.2d:%.2d \r\n", ( uint16_t ) time.hours, ( uint16_t ) time.min, ( uint16_t ) time.sec );
        log_printf( &logger,"--------------------------\r\n" );
    }
    sec_flag = time.sec;
}

void main ( void ) {
    application_init( );

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

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

Additional Support

Resources

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