What is it?

Introducing the Miniature RTC PCF8523 Real Time Clock Breakout Board, designed specifically for the makers community who are looking for compact and efficient timekeeping solutions. This innovative board is powered by 2 x Size 10 Hearing Aid batteries, making it one of the smallest and most lightweight RTC modules on the market. The board features the reliable PCF8523 RTC IC, ensuring accurate and stable timekeeping. The PCF8523 is a CMOS Real-Time Clock (RTC) and calendar optimized for low power consumption. Data is transferred serially via the I2C-bus with a maximum data rate of 1000 kbit/s. Alarm and timer functions are available with the possibility to generate a wake-up signal on an interrupt pin. An offset register allows fine-tuning of the clock. The PCF8523 has a backup battery switch-over circuit, which detects power failures and automatically switches to the battery supply when a power failure occurs.

This RTC board uses Size 10 batteries (originally made for hearing aids). The size 10 battery offers high energy density in a very small package. Take the Rayovac R-10AE-6 ZM battery as an example: it has dimensions of just 5.8mm x 3.6mm and boasts a specification of 1.45V / 250mAh (source from Digikey). This RTC board stacks 2 of these batteries together using a custom resin 3D printed housing. You can purchase Size 10 batteries online from Digikey and Amazon, or offline at places like CVS and Walgreens.

Key Features

• Ultra-Compact Design: The use of Size 10 Hearing Aid batteries allows for a significantly smaller footprint compared to traditional CR2016/CR2032 coin battery-powered boards.

• Low Power Consumption: The PCF8523 RTC IC is known for its low power usage, making it an ideal match for the long-lasting Size 10 batteries.

• High Accuracy: The board maintains timekeeping accuracy within a few parts per million, ensuring you never lose track of time.

• Easy Integration: Comes with standard I2C interface, making it easy to integrate with microcontrollers like Arduino, Raspberry Pi, and more.

• Extended Battery Life: The Size 10 batteries provide sufficient power to keep the RTC running for an extended period, reducing the frequency of battery replacements.

To use it, simply connect 3V3 power and GND, along with SCL and SDA (I2C connections) to your microcontroller. You can then use open source Arduino libraries such as: RTClib

Some potential applications:

Wearable Tech The miniature size of this RTC breakout board makes it perfect for wearable tech projects like smartwatches, fitness trackers, and medical alert systems where space is at a premium.

Drone Timing Systems Incorporate this tiny RTC into your drone's flight control system to accurately log flight times, coordinate multi-drone operations, or time-stamp sensor data.

Compact IoT Devices Ideal for IoT devices with space constraints, such as smart door locks, asset trackers, or compact environmental sensors.

Miniature Robotics Perfect for small-scale robotics projects where every millimeter of space counts. Use it to coordinate movements, log operational data, or manage sleep/wake cycles.

Portable Game Consoles For DIY portable game consoles, this RTC can manage real-world time without taking up much space, allowing for more room for other components like additional buttons or a larger screen.

Embedded Systems in Vehicles Its small size allows it to be easily embedded in automotive systems for functions like time-stamping, data logging, or coordinating time-sensitive operations.