MikroElektronika (MIKROE) has released a new Click board featuring the NXP Semiconductors PCF8523 real-time clock (RTC), designed to provide ultra-low-power timekeeping for embedded systems. The module integrates a clock and calendar with alarm, watchdog, and timestamp functions, communicating via an I2C-bus interface and operating at voltages as low as 1.2V.
Technical Specifications of the PCF8523 RTC
The PCF8523 RTC is engineered for applications where energy efficiency is critical, such as battery-operated portable devices. According to the NXP Semiconductors datasheet, the device consumes minimal current, allowing it to maintain accurate timekeeping even when the main system power is removed.
The board includes:
- Timekeeping: A clock and calendar function that tracks seconds, minutes, hours, days, weekdays, months, and years.
- I2C Interface: A 400 kHz two-line serial interface for communication with host microcontrollers.
- Programmable Features: Users can configure alarm interrupts and a watchdog timer to trigger system resets or wake-up events.
- Power Management: An integrated power-management circuit handles the transition between main power and a backup battery source automatically.
Integration via the Click Board Ecosystem
MIKROE’s Click board format standardizes the integration of the PCF8523 by utilizing the proprietary mikroBUS socket. This design allows developers to plug the module directly into development boards without manual wiring.
As noted in the MIKROE product documentation, the board includes a dedicated holder for a CR1225 coin cell battery, which ensures the RTC continues to run during power outages. The hardware also features internal offset registers that allow for software-based clock calibration, enabling developers to compensate for frequency deviations caused by the crystal oscillator.
Comparison of RTC Power Profiles
The PCF8523 is categorized by NXP as an ultra-low-power device, specifically optimized for long-term battery life. When compared to standard RTCs, the PCF8523 offers distinct advantages in low-voltage environments.
| Feature | PCF8523 RTC | Standard RTC (Typical) |
|---|---|---|
| Minimum Operating Voltage | 1.2V | 2.0V – 3.0V |
| Backup Current (at 3V) | ~150 nA | ~300 nA – 500 nA |
| Interface | I2C | I2C / SPI |
The ability to operate down to 1.2V is a significant factor for designers using single-cell alkaline or lithium-ion battery chemistries, as it extends the functional life of the backup power source.
Use Cases in Embedded Design
The inclusion of a watchdog timer and timestamp functionality makes this module suitable for industrial data logging and secure system monitoring. The watchdog timer provides a fail-safe mechanism, resetting the microcontroller if the software enters an infinite loop or crashes. Simultaneously, the timestamp feature records specific events, which is essential for audit trails in remote monitoring sensors or smart metering equipment where power availability is inconsistent.
The module is currently available through the MIKROE online store and authorized global distributors. Designers can access software libraries via the MIKROE Libstock repository to accelerate the integration of the RTC into firmware projects.
Worth a look