HOW DOES IT WORK?

RTC 13 Click as its foundation uses the PCF2123, an SPI configurable real-time clock/calendar optimized for low power operations from NXP Semiconductors. It contains sixteen 8-bit registers with an auto-incrementing address counter, an on-chip 32.768kHz oscillator with two integrated load capacitors, a frequency divider that provides the source clock for the RTC, and a programmable clock output. The integrated oscillator ensures year, month, day, weekday, hours, minutes, and seconds, making this Click board™ suitable for various time-keeping applications such as high-duration timers, daily alarms, and many more.

The PCF2123 communicates with MCU using the standard SPI serial interface with a maximum frequency of 8MHz, where data transfers serially with a maximum data rate of 6.25 Mbit/s. An alarm and timer function is also available, providing the possibility to generate a wake-up signal on an interrupt line, available on the INT pin of the mikroBUS™ socket, and indicated by a red LED marked as INT.

Besides, this Click board™ also has an onboard header labeled CLKOUT, which provides a programmable square-wave output clock signal controlled by one GPIO pin, a CLE pin routed to the RTS pin the mikroBUS™ socket. Frequencies of 32.768kHz, representing a default value down to 1Hz, can be generated and used as a system and MCU clock, input to a charge pump, or calibration of the oscillator.

The most common RTC configuration, like this one, is a battery-backed up, which maintains time and continues its work without interruption in the event of a power failure. That's why, in addition to the PCF2123, the RTC 13 Click is equipped with a button cell battery holder compatible with the 3000TR battery holder, suitable for 12mm Coin Cell batteries.

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. 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.