RTC 3 Click

How does it work?

RTC 3 Click is based on the BQ32000, a real-time clock from Texas Instruments presenting a compatible replacement for industry standard real-time clocks. The BQ32000 features an automatic backup supply with an integrated trickle charger for an automatic switchover to a backup power supply providing additional reliability (the circuit maintains the backup charge with an onboard supercapacitor). It also comes with a programmable calibration adjustment from –63ppm to +126ppm and clock frequency derived from an onboard 32.768KHz oscillator.

The BQ32000 communicates with the MCU using the standard I2C 2-Wire interface with a maximum frequency of 400kHz. Its time registers are updated once per second, with registers updated simultaneously to prevent a time-keeping glitch. It should be noted that when the BQ32000 switches from the main power supply to the backup supply, the time-keeping register cannot be accessed via the I2C interface. The access to these registers is only with supply voltage present. The time-keeping registers can take up to one second to update after the device switches from the backup power supply to the main power supply.

The BQ32000 also includes an automatic leap year correction, and general interrupt or oscillator fail flag indicating the status of the RTC oscillator routed to the INT pin of the mikroBUS™ socket. The RTC classifies a leap year as any year evenly divisible by 4. Using this rule allows for reliable leap-year compensation until 2100. The host MCU must compensate for years that fall outside this rule.

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. However, the Click board™ comes equipped with a library containing 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 3 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	INT	Interrupt
	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	NC
Ground	GND	8	GND	GND	9	GND	Ground

Onboard settings and indicators

RTC 3 Click electrical specifications

Software Support

We provide a library for the RTC 3 Click as well as a demo application (example), developed using MikroElektronika compilers. The demo can run on all the main MikroElektronika development boards.

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

Library Description

This library contains API for RTC 3 Click driver.

Key functions

• Function sets time: hours, minutes and seconds data to

• the target register address of PCF8583 chip on RTC 3 Click.

• Function gets time: hours, minutes and seconds data from

• the target register address of PCF8583 chip on RTC 3 Click.

• Function set calibration by write CAL_CFG1 register of BQ32000 chip.

Example Description

This application enables time measurment over RTC 3 Click.

 void application_task ( void ) 
 { 
     //  Task implementation. 

     uint8_t time_seconds_new = 0xFF; 



     rtc3_get_time( &rtc3 ); 

     rtc3_get_date( &rtc3 ); 

     if ( time_seconds_new != rtc3.time.time_seconds ) 
     { 
         if ( ( ( rtc3.time.time_hours | rtc3.time.time_minutes | rtc3.time.time_seconds ) == 0 )  && ( ( rtc3.date.date_day | rtc3.date.date_month ) == 1 ) ) 
         { 
             log_printf( &logger, "  Happy New Year  rn" ); 
             log_printf( &logger, "------------------rn" ); 
         } 

         log_printf( &logger, " Time : %d:%d:%d rn Date: %d.%d.20%d.rn------------------rn", rtc3.time.time_hours, rtc3.time.time_minutes, 
                                                                                             rtc3.time.time_seconds,  
                                                                                             rtc3.date.date_day, rtc3.date.date_month, rtc3.date.date_year ); 

         time_seconds_new = rtc3.time.time_seconds; 
     } 

     Delay_ms( 200 ); 
 }

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

Other Mikroe Libraries used in the example:

• MikroSDK.Board
• MikroSDK.Log
• Click.Rtc3

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 MikroElektronika compilers.

mikroSDK

This Click board™ is supported with mikroSDK - MikroElektronika Software Development Kit. To ensure proper operation of mikroSDK compliant Click board™ demo applications, mikroSDK should be downloaded from the LibStock and installed for the compiler you are using.

For more information about mikroSDK, visit the official page.