RTC 6 Click

How does it work?

RTC 6 Click is based on the MCP79410, a battery-backed I2C real-time clock/calendar with SRAM, and protected EEPROM from Microchip. The alarms on this RTC 6 Click can be configured on all counters up to and including months. The clock frequency is delivered from an onboard 32.768KHz crystal oscillator. On-chip digital trimming with ±1 ppm resolution and ±129 ppm range can be used to adjust for frequency variance caused by crystal tolerance and temperature. For backup power for the RTC, this Click board™ features the coin-cell Lithium battery holder that supports CR1216, CR1220, and CR1225 battery formats. By removing the 0ohm resistor, you can disable battery backup.

For storing data, the MCP79411 has 64 bytes of battery-backed SRAM that correlate with the timekeeping circuit and allow the device to maintain accurate time and date when main power is lost. The time between power switches, from backup to primary power and vice versa, is restored is recorded by the power outage time stamp. The MCP79411 features 1Kbit of internal nonvolatile EEPROM with software write protectable regions. An additional 64 bits of protected nonvolatile memory is only writable after an unlock sequence, making it ideal for storing a unique ID or other critical information.

The RTC 6 Click uses an I2C interface for communication with the host MCU, with a clock rate of up to 400KHz. This Click board™ also features a multifunction pin, accessible over the MFP pin of the mikroBUS™ socket. The multifunctional output on this pin can be configured to assert an alarm match to output a selectable frequency square wave or as a general-purpose output. The MCP79411 features two independent alarms. Each alarm can be used to either generate an interrupt at a specific time in the future or to generate a periodic interrupt every minute, hour, day, day of week, or month.

This Click board™ can operate with either 3.3V or 5V logic voltage levels selected via the PWR SEL jumper. This way, both 3.3V and 5V capable MCUs can use the communication lines properly. However, the 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.

Specifications

Pinout diagram

This table shows how the pinout on RTC 6 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	MFP	Multifunction Pin
	NC	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 6 Click electrical specifications

Software Support

We provide a library for the RTC 6 Click as well as a demo application (example), developed using MIKROE compilers. The demo can run on all the main MIKROE development boards.

Package can be downloaded/installed directly from NECTO Studio Package Manager (recommended), downloaded from our LibStock™ or found on MIKROE github account.

Library Description

This library contains API for RTC 6 Click driver.

Key functions

• This function enables automatic switch to battery on VCC failure.

• This function gets current GMT time and sets it in the RTC.

• his function calculates current local time.

Example Description

This application enables usage of Real-TIme clock and calendar with alarm on RTC 6 click.

 void application_task ( void ) 
 { 
     //  Task implementation. 

     rtc6_get_gmt_time( &rtc6, &utc_time ); 
     rtc6_get_local_time( &rtc6, &local_time ); 

     log_printf( &logger, "--- UTC time ---rnTime : %d %d %drn", utc_time.hours, utc_time.minutes, utc_time.seconds ); 

     log_printf( &logger, "Date : %d %d %drn", utc_time.monthday, utc_time.month, utc_time.year ); 

     log_printf( &logger, "--- Local time ---rnTime : %d %d %drn", local_time.hours, local_time.minutes, local_time.seconds ); 

     log_printf( &logger, "Date : %d %d %drn rn", local_time.monthday, local_time.month, local_time.year ); 

     if ( rtc6_is_active_alarm( &rtc6 ) != 0 ) 
     { 
         log_printf( &logger, " ----- Active alarm ----- rn" ); 
         rtc6_disable_alarm( &rtc6, RTC6_ALARM_0 ); 
         rtc6_repeat_alarm( &rtc6, RTC6_ALARM_0, 20 ); 
     } 

     Delay_ms( 900 ); 
 }

The full application code, and ready to use projects can be installed directly from NECTO Studio Package Manager (recommended), downloaded from our LibStock™ or found on MIKROE github account.

Other MIKROE Libraries used in the example:

• MikroSDK.Board
• MikroSDK.Log
• Click.Rtc6

Additional notes and informations

Depending on the development board you are using, you may need USB UART click, USB UART 2 Click or RS232 Click to connect to your PC, for development systems with no UART to USB interface available on the board. UART terminal is available in all MIKROE compilers.

mikroSDK

This Click board™ is supported with mikroSDK – MIKROE Software Development Kit, that needs to be downloaded from the LibStock and installed for the compiler you are using to ensure proper operation of mikroSDK compliant Click board™ demo applications.

For more information about mikroSDK, visit the official page.