DS3231 RTC Module

I designed this module to use with some of my upcoming clock projects.

The DS3231 RTC chip has very good for timekeeping as it has a temperature compensated oscillator which can also be finely adjusted by clock firmware to allow for manufacturing tolerances and aging.

This project uses SMD components.

1. DS3231SN RTC SMD IC U1
2. 4.7K SMD (1206) resistor (472) X 3 R1 - R3
3. 1K SMD (1206) resistor (102) R4
4. 0.1uF SMD 50v (1206) Ceramic Capacitor C1
5. SMD Red LED (1206) D1
6. CR1220 SMD Coin cell holder
7. CR1220 Coin cell
8. 5 way 2.54mm pin header
9. Custom PCB

Here is the schematic. It is just has the necessary components, pull-up resistors for the I2C ports plus the SQW output is available (which can be used for more precise timing). An LED is provided which can either be controlled by a clock's firmware or just show that the RTC is powered on.

Here is the small double-sided PCB. I had it manufactured by JLCPCB. All the Gerber files for it can be downloaded from my website.

1. Solder the DS3231 IC first.
2. Then the SMD resistors, Capacitor and LED.
3. Turn over the PCB and fit the LED (with the green dot nearest the corner of the board - as shown in photo).
4. Clean the PCB with flux cleaner and check all solder joints.
5. Fit the coin-cell holder.
6. Fit the 5 way header strip, ensure it is vertical.
7. Use flux cleaner to remove flux residue from the header pins and coin-cell holder.

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

This module is intended to be used with some of my upcoming clock projects.

(When connected to one of my clock projects, it will display an error message if the module is not working.)