DS3231

Connects over

I²C

Address

0x68

Made by

Maxim Integrated (Analog Devices)

Datasheet

datasheets.maximintegrated.com

Use it

hardware {
    device ds3231: DS3231
}

every 1s {
    let value: int = ds3231.hours()
    log("ds3231", "hours={value}")
}

On its own, the declaration puts the DS3231 on the first I²C bus (SDA 21, SCL 22 on the ESP32) at 0x68. To choose the pins or the address, declare the bus and attach the device: device ds3231: DS3231 on i2c0 at 0x68 with i2c i2c0(sda: 21, scl: 22).

Methods

• ds3231.hours() -> int

  Hour 0-23

• ds3231.minutes() -> int

  Minute 0-59

• ds3231.seconds() -> int

  Second 0-59

• ds3231.year() -> int

  Year 2000-2099

• ds3231.month() -> int

  Month 1-12

• ds3231.date() -> int

  Day 1-31

• ds3231.temperature() -> float

  RTC temperature °C

Wiring

Specifications

Voltage

2.3V – 5.5V

Current

150 μA active, 1 μA standby (battery)

Accuracy

±2 ppm (0–40°C) ≈ ±1 minute / year

Temp sensor

Built-in ±3°C

Battery life

8–10 years on CR2032

Tips

• TCXO (temperature-compensated XO) — orders of magnitude more accurate than DS1307.
• Battery (CR2032) keeps time across power cycles.
• Built-in temperature sensor is for clock compensation but exposed as a regular read.

Alternatives worth knowing:

• DS1307: Cheaper but drifts ~20 s/month vs. DS3231's ~1 s/month. Skip it.
• PCF8523: NXP equivalent — slightly lower accuracy, very low power.