PCF85063A Breakout Real-Time Clock (RTC) - Compact Real-Time Clock Module

What it is

A compact open-source RTC breakout board based on the PCF85063A real-time clock IC. It gives a microcontroller a dedicated timekeeping chip instead of relying only on internal counters.

Main components

• PCF85063A real-time clock IC
• Qwiic/easyC connector for I2C
• SCL, SDA, VCC, and GND pins
• Backup battery holder
• Mounting holes for fixing the board inside a small product or prototype

What you can use it for

• IoT devices that need timestamps
• Sensor data loggers
• Mini robots or embedded products with schedules
• Clocks, timers, alarms, or wake-up logic
• Battery-powered prototypes that need low-power timekeeping

Notes before use

• Nastrotek has not independently fabricated or tested this board yet.
• Review the schematic, PCB layout, BOM, and license before manufacturing.
• Check the I2C voltage level and connector pinout against your controller board.
• Confirm battery holder clearance if the board will be installed inside an enclosure.

Source / reference

Original hardware design by Soldered Electronics.

The render, model, and design files shown here come from the original hardware documentation and are attributed to Soldered Electronics under the TAPR Open Hardware License. Two product photographs without a separate image license were removed; Nastrotek does not claim ownership of the board or original assets.

How to evaluate this board

Read this resource as a starting point for review, not as a board you should manufacture blindly. Open the schematic first and identify the power input, regulator path, MCU or main controller, external connectors, programming interface, and any sensor or display interfaces. Once the functional blocks are clear, it becomes much easier to decide whether the design matches your project.

For a tiny RTC breakout, the useful review is narrower: confirm the I2C pull-ups, backup-battery path, oscillator/crystal requirements if present, address conflicts, mounting-hole clearance, and connector order. I would label VCC/GND/SDA/SCL very clearly, because this kind of board is often wired by hand during a quick prototype.

Before reusing the files

• Check the license and original author notes.
• Confirm voltage levels before connecting external modules.
• Verify connector pinout against your cables and sensors.
• Review BOM availability before ordering PCBs.
• Export fresh Gerbers from the design tool if you modify anything.
• Treat untested designs as references until you have fabricated and measured them.

Good use cases

This kind of resource is useful when you want to study a real open-source hardware design, borrow part of a circuit, or compare layout decisions before creating your own board. Even if you do not fabricate the PCB directly, the schematic can still be valuable as a reference for power design, connector planning, enclosure constraints, or firmware bring-up.

For a small product prototype, the best workflow is to reuse ideas carefully: copy the principle, not the entire board without context. Mark what you changed, keep notes on assumptions, and add measurement points so the first fabricated board can teach you something useful.

Documentation tip

If you adapt the board, keep a small change log beside the design files. Note changed connectors, swapped parts, new voltage assumptions, and anything that must be measured during bring-up.

Related reading

• PCB review checklist
• ESP32 schematic review checklist
• Net classes and trace width rules
• Ground plane basics for PCB layout