The MikroElektronika MIKROE-947 RTC Click is an accessory board in mikroBus™ form factor. This board features NXP's NXP's PCF8583 serial RTC. It is a low-power, full binary-coded decimal (BCD) clock/calendar. Communication to the board is done via an I2C interface. The RTC click board features a 3 V / 230 mA lithium battery as a backup power supply which ensures that timekeeping operation continues even when the main power supply goes OFF. The board is set to use 3.3 V power supply by default. To run on 5.0 V, simply solder the PWR SEL SMD jumper to 5 V position. The MIKROE-947 RTC click is ideal for applications that require real-time clocks, calendars, and programmed alarms. Communication with the board is done over standard I2C interface. The RTC has 24-hour or 12-hour format, a programmable alarm, timer, and interrupt function.

The PCF8583 is a clock and calendar chip based on a 2048-bit static CMOS1 RAM organized as 256 words by 8 bits. Addresses and data are transferred serially via the two-line bidirectional I2C bus. The built-in word address register is incremented automatically after each written or read data byte. Address pin A0 is used for programming the hardware address, allowing the connection of two devices to the bus without additional hardware. The built-in 32.768 kHz oscillator circuit and the first 8 bytes of the RAM are used for the clock, calendar, and counter functions. The next 8 bytes can be programmed as alarm registers or used as free RAM space. The remaining 240 bytes are free RAM locations.