DS3231 RTC Module

I designed this module for some of my upcoming clock projects.

Features

• Uses a small replaceable CR1220 coin-cell
• Compact design for soldering onto a main PCB. (22 x 15 x 8 mm)
• Includes SQW pin output (useful for one second pulses)
• Has an LED status indicator
• Ability to test its timing accuracy, if calibration is required.
• Easy to plug into a breadboard

Parts List

This project uses SMD components.

• DS3231SN RTC SMD IC U1
• 4.7K SMD (1206) resistor (472) X 3 R1 – R3
• 1K SMD (1206) resistor (102) R4
• 0.1uF SMD 50v (1206) Ceramic Capacitor C1
• SMD Red LED (1206) D1
• CR1220 SMD Coin cell holder
• CR1220 Coin cell
• 5 way 2.54mm pin header
• Custom PCB

Schematic

PCB

Here is the small double-sided PCB. I had it manufactured by JLCPCB. The Gerber files can be downloaded below.

Construction and Testing

Solder the DS3231 IC first.

Then the SMD resistors, Capacitor and LED.

Turn over the PCB and fit the LED (with the green dot nearest the corner of the board – as shown).

Clean the PCB with flux cleaner and check all solder joints.

Fit the coin-cell holder.

Fit the 5 way header strip, ensure it is vertical.

Use flux cleaner to remove flux residue from the header pins and coin-cell holder.

Testing

If a regulated 5V power supply is connected, the LED should light.

No further testing at this stage.