ET-A11
DS3231 Precision RTC
±2 ppm temperature-compensated clock with coin-cell backup, Qwiic
AED 39.00
Out of stockOverview
±2 ppm temperature-compensated clock with coin-cell backup, Qwiic
The ET-A11 is built around the Maxim DS3231SN — integrated TCXO + crystal, ±2ppm 0–40°C (≈1 min/year), 2 alarms, temperature sensor. It connects over I²C fixed 0x68 and is powered from 2.3–5.5V from Qwiic.
Two Qwiic / STEMMA QT connectors let you chain it with other boards without soldering, and the 2.54 mm header fits a breadboard.
Designed in Dubai by ElectroTrical — the full schematic, BOM and design notes are published below.
Good for
- Clocks that keep time for years
- Data loggers with timestamps
- Scheduled automation
Key features
What makes it different
RTC
Maxim DS3231SN: integrated TCXO + crystal, ±2ppm 0–40°C (≈1 min/year), 2 alarms, temperature sensor
Interface
I2C fixed 0x68
Backup
CR1220 holder (battery not included)
Supply
2.3–5.5V from Qwiic
Qwiic / STEMMA QT
Two JST-SH connectors plus a 2.54 mm header — 3.3 V and 5 V hosts.
Open documentation
Schematic, BOM and layout notes published for every board.
Specifications
Technical specifications
| RTC | Maxim DS3231SN: integrated TCXO + crystal, ±2ppm 0–40°C (≈1 min/year), 2 alarms, temperature sensor |
|---|---|
| Interface | I2C fixed 0x68 |
| Backup | CR1220 holder (battery not included) |
| Supply | 2.3–5.5V from Qwiic |
| Size | 25.4 × 25.4 mm |
|---|---|
| Mounting | 4 × M2.5 holes, 2.54 mm from each corner |
| Connectors | 2 × Qwiic / STEMMA QT (JST SH 4-pin) · 7-pin 2.54 mm header |
| Main IC | DS3231SN# (LCSC C722469) |
| Revision | Rev A |
| Libraries | RTClib (Adafruit), ESPHome ds1307-compatible / ds3231 external, Linux rtc-ds1307 |
|---|
| JP1 (default Closed) | Cut to turn off the LED |
|---|---|
| JP2 (default Closed) | Cut to remove the host-side I2C pull-ups |
Performance
Accuracy
Pinout
Pin map and connections
| Pin | Name | Type | Function |
|---|---|---|---|
| 1 | VIN | Power | Sensor supply = host logic level |
| 2 | GND | Ground | Ground |
| 3 | SCL | I²C | I²C clock |
| 4 | SDA | I²C | I²C data |
| 5 | SQW | Output | Alarm / 1Hz square wave, open-drain |
| 6 | 32K | Output | 32.768kHz output, open-drain |
| 7 | RST | Control | Reset I/O, active low |
Qwiic / STEMMA QT pins: GND, VIN, SDA, SCL (same on both connectors). I²C pull-ups (10 kΩ) are on the board; cut JP2 to remove them.
Mechanical
Dimensions and what's in the box
In the box
- 1 × ET-A11 DS3231 Precision RTC (assembled)
- 1 × 7-pin 2.54 mm male header, unsoldered
Getting started
- Plug in a Qwiic / STEMMA QT cable, or solder the header and wire VIN, GND, SDA and SCL
- Libraries: RTClib (Adafruit), ESPHome
ds1307-compatible /ds3231external, Linux rtc-ds1307 - Run an I²C scanner to confirm the address: 0x68
Compare
Which real-time clock?
| DS3231 Precision RTC (this board)This board | ET-A12 PCF8563 Low-Power RTC | |
|---|---|---|
| What it does | ±2 ppm temperature-compensated clock with coin-cell backup, Qwiic | Real-time clock using only 0.25 µA, Qwiic |
| Interface | I²C fixed 0x68 | I²C 0x51 |
| Best for | Clocks that keep time for years | Battery loggers |
| Price | 39 AED | 15 AED |
Downloads
Documents and design files
Need a custom version of this board?
Different connector, size or sensor? We design and build custom variants.