RTC 12 Click is a compact add-on board that measures the passage of time. This board features the DS1343, a low-current SPI-configurable real-time clock (RTC) from Analog Devices. This timekeeping device provides an extremely low standby current permitting longer life from a backup supply source. Its clock/calendar feature provides seconds, minutes, hours, day, date, month, and year information. The date at the end of the month is automatically adjusted for months with fewer than 31 days, including corrections for leap year. The clock operates in either 24-hour or 12-hour format with an AM/PM indicator. This Click board™ is suitable for portable applications, industrial and health-related time metering applications, and others requiring an accurate RTC for their operation.

RTC 12 Click is supported by a mikroSDK compliant library, which includes functions that simplify software development.

RTC 12 Click as its foundation uses the DS1343, a low-current RTC that consumes an extremely low timekeeping current permitting longer life from a backup supply source from Analog Devices. The devices provide a full binary-coded decimal clock calendar accessed by a simple serial interface. The clock/calendar provides seconds, minutes, hours, day, date, month, and year information. The month's end date is automatically adjusted for months with fewer than 31 days, including corrections for leap year through 2099. The clock operates in either a 24-hour or 12-hour format with an AM/PM indicator.

As performed on this Click board™, the most common configuration is a battery-backed up RTC, which maintains time and may hold data in 96 bytes of NV RAM provided for data storage. In addition to the DS1343, the RTC 12 Click is equipped with a button cell battery holder compatible with the 3000TR battery holder, suitable for 12mm Coin Cell batteries. Furthermore, it also has a built-in temperature-compensated power-sense circuit that detects power failures and automatically switches to the backup supply, thus allowing for uninterrupted operation.

The DS1343 communicates with MCU using the standard SPI serial interface that supports modes 1 and 3 with a maximum frequency of 4 MHz. It also provides two programmable time-of-day alarms. Each alarm can generate an interrupt on a programmable combination of seconds, minutes, hours, and days, available on the INT pin of the mikroBUS™ socket. The interrupt selection can be made by positioning the SMD jumper labeled INT SEL to an appropriate position. Both interrupt outputs operate when the device is powered by mikroBUS™ power rails or backup supply voltage.

In addition to the features mentioned above, the user can use another additional indicator routed to the AN pin of the mikroBUS™ socket labeled as PF to indicate a loss of a primary power supply, VCC from mikroBUS™ power rails.

This Click board™ can operate with both 3.3V and 5V logic voltage levels selected via the VCC SEL jumper. This way, it is allowed for both 3.3V and 5V capable MCUs to use the SPI communication lines properly. In addition, 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.

• Interface: SPI
• Compatibility: mikroBUS™
• Dimensions: 42.9 x 25.4mm
• Input Voltage: 3.3V or 5V
• Supply Voltage VCC: Min. 3.3V, Max. 5V
• Battery Supply Voltage: Min. 1.3V, Max. 5.5V
• RTC Memory Size: 96 bytes
• Operating Temperature Range: Min. -40°C, Typ. +25°C, Max. +85°C

• Schematic
• DS1343 Datasheet
• mikroSDK
• GitHub