RTC 9 Click Board™

Product Code: MIKROE-4121

How Does The RTC 9 Click Board™Work? The RTC 9 Click Board™ is based on the M41T82, an extreme low power real-time clock/calendar (RTC) module from ST Microelectronics. Thanks to its high integration level, this module provides high time accuracy, factory calibrated to ±5 ppm even after two reflows, 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 operational parameters are stored within the internal user SRAM memory, which is battery-backed, thus allowing their persistence in the event of the complete power failure. M41T82 features a built-in 32.768 kHz oscillator. However, the RTC 9 Click Board™ has an external oscillator too, in order to achieve the best accuracy possible. Eight bytes of the register map are used for the clock/calendar function and are configured in binary-coded decimal (BCD) format. An additional 17 bytes of the register map provide status/control of the two alarms, watchdog, 8-bit counter, and square wave functions.

An additional seven bytes are made available as user SRAM. M41T82 supports the I2C communication interface, which is also used on the RTC 9 Click Board™ for communicating with the main microcontroller through the mikroBUS socket. Functions available to the user include a non-volatile, time-of-day clock/calendar, two alarm interrupts, watchdog timer, programmable 8-bit counter, and square wave outputs. The eight clock address locations contain the century, year, month, date, day, hour, minute, second, and tenths/hundredths of a second in 24-hour BCD format. Corrections for 28, 29 (leap year), 30, and 31 day months are made automatically. The RTC 9 Click Board™ is designed to be operated with both 3.3V and 5V logic levels that can be selected via VCC SEL jumper. This allows for both 3.3V and 5V capable MCUs to use the I2C communication lines properly. SPECIFICATIONS Type RTC Applications The RTC 9 Click Board™ is a perfect solution for the development of the IoT, wearable and portable devices, logging devices, industrial and health-related time metering applications, and all the other applications that require an accurate time-base for various purposes. On-board modules M41T82, real-time clock (RTC) with battery switchover, from ST Microelectronics. Key Features Factory-calibrated accuracy of ±5 ppm typically, automatic switchover and reset output circuitry, programmable alarm with interrupt function, and more Interface I2C Compatibility mikroBUS Click board size M (42.9 x 25.4 mm) Input Voltage 3.3V or 5V PINOUT DIAGRAM This table shows how the pinout on the RTC 9 Click Board™ 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 Reset RST 2 RST INT 15 NC 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 Label Name Default Description LD1 PWR - Power LED Indicator JP1 VCC SEL Left Power Supply Voltage Selection 3V3/5V, left position 3v3, right position 5v RTC 9 CLICK ELECTRICAL SPECIFICATIONS Description Min Typ Max Unit Supply Voltage (for R version) 2.70 3.3 5.5 V Supply Current