RTC 24 Click

How does it work?

RTC 24 Click is based on the DS1307, a serial real-time clock (RTC) module from Analog Devices, which features a 64x8 bit battery-backed NV SRAM alongside its full binary-coded decimal (BCD) clock/calendar functionality. This board provides highly accurate real-time clock and calendar functions for embedded applications, enabling precise timekeeping even during power interruptions. The clock/calendar maintains complete time data, including seconds, minutes, hours, day, date, month, and year, with built-in logic to automatically adjust the date at the end of each month, accounting for months with fewer than 31 days and incorporating leap-year compensation valid up to the year 2100. The device supports both 24-hour and 12-hour formats with an AM/PM indicator, making it flexible for various regional and application-specific requirements.

This Click board™ is designed in a unique format supporting the newly introduced MIKROE feature called "Click Snap." Unlike the standardized version of Click boards, this feature allows the main sensor area to become movable by breaking the PCB, opening up many new possibilities for implementation. Thanks to the Snap feature, the DS1307 can operate autonomously by accessing its signals directly on the pins marked 1-8. Additionally, the Snap part includes a specified and fixed screw hole position, enabling users to secure the Snap board in their desired location.

Communication with the host MCU is established through a standard I2C interface, allowing for straightforward integration and reliable data transfer. In addition to the standard I2C pins, RTC 24 Click uses the SQW pin, which can output one of four selectable square-wave frequencies: 1Hz, 4kHz, 8kHz, or 32kHz, allowing the board to provide an accurate clock signal or act as an output driver for synchronization purposes in complex systems. The board also integrates a VBAT SEL switch that allows users to select the backup power source for the RTC module. This switch enables the selection between the onboard lithium cell battery or an external 3V backup supply provided via the VEXT pin, located directly next to the switch, ensuring uninterrupted operation and flexible power management depending on system design requirements.

A built-in power-sense circuit within the DS1307 automatically detects power failures and switches to the selected backup supply, preserving timekeeping data at all times. This combination of features makes RTC 24 Click an ideal solution for applications such as data loggers, metering systems, industrial automation, and any embedded system that requires dependable and continuous real-time tracking.

This Click board™ can operate with either 3.3V or 5V logic voltage levels selected via the VCC SEL jumper. This way, both 3.3V and 5V capable MCUs can use the communication lines properly. Also, this Click board™ comes equipped with a library containing easy-to-use functions and an example code that can be used as a reference for further development.

Click Snap

Click Snap is an innovative feature of our standardized Click add-on boards, designed to bring greater flexibility and optimize your prototypes. By simply snapping the PCB along predefined lines, you can easily detach the main sensor/IC/module area, reducing the overall size, weight, and power consumption - ideal for the final phase of prototyping. For more details about Click Snap, visit the official page dedicated to this feature.

Specifications

Pinout diagram

This table shows how the pinout on RTC 24 Click corresponds to the pinout on the mikroBUS™ socket (the latter shown in the two middle columns).

Notes	Pin					Pin	Notes
	NC	1	AN	PWM	16	NC
	NC	2	RST	INT	15	SQW	Square-Wave Output
ID COMM	CS	3	CS	RX	14	NC
	NC	4	SCK	TX	13	NC
	NC	5	MISO	SCL	12	SCL	I2C Clock
	NC	6	MOSI	SDA	11	SDA	I2C Data
Power Supply	3.3V	7	3.3V	5V	10	5V	Power Supply
Ground	GND	8	GND	GND	9	GND	Ground

Onboard settings and indicators

RTC 24 Click electrical specifications

Software Support

RTC 24 Click demo application is developed using the NECTO Studio, ensuring compatibility with mikroSDK's open-source libraries and tools. Designed for plug-and-play implementation and testing, the demo is fully compatible with all development, starter, and mikromedia boards featuring a mikroBUS™ socket.

Example Description

This example demonstrates the use of the RTC 24 Click board by initializing the device and setting up the current time and date. It continuously reads and displays the updated time and date every second using the square wave pin.

Key Functions

• rtc24_cfg_setup This function initializes Click configuration structure to initial values.
• rtc24_init This function initializes all necessary pins and peripherals used for this Click board.
• rtc24_default_cfg This function executes a default configuration of RTC 24 Click board.
• rtc24_set_time This function sets the current time (hours, minutes, seconds) in the RTC.
• rtc24_read_time This function reads the current time (hours, minutes, seconds) from the RTC.
• rtc24_read_date This function reads the current date (day, day of week, month, year) from the RTC.

Application Init

Initializes the logger and the RTC 24 Click driver, applies the default configuration, and sets the starting time and date.

Application Task

Waits for a 1 Hz square wave signal and then reads and displays the current time and date.

Application Output

This Click board can be interfaced and monitored in two ways:

• Application Output - Use the "Application Output" window in Debug mode for real-time data monitoring. Set it up properly by following this tutorial.
• UART Terminal - Monitor data via the UART Terminal using a USB to UART converter. For detailed instructions, check out this tutorial.

Additional Notes and Information

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.