DS3231 RTC
Also known as: DS3231 · ZS-042 · More staples
Correct time without Wi-Fi: schedules and data logging that survive an internet outage or an off-grid deployment. The ESPHome ds1307 component speaks to it directly.
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At a glance
⚑ flag an error| Measures | time |
|---|---|
| Accuracy | ±2 ppm temperature-compensated RTC (~1 min/year) |
| Interface | I2C @ 0x68 |
| Supply | 3.3–5 V + coin cell |
| Battery-viable | Yes (deep-sleep friendly) |
| ESPHome | Native ESPHome component — ds1307 |
| Typical price | $1-2 (street, varies) |
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Clone check
Medium clone risk. DS3231M dies remarked as the better SN grade drift more (±5 ppm) — still fine for home use.
Good for
Gotchas to know
- The classic ZS-042 board has a charging circuit that COOKS non-rechargeable CR2032s — snip the diode/resistor or fit a rechargeable LIR2032.
- Shares 0x68 with the MPU6050 — mind the bus if you use both.
Wiring it up
It's I2C, so it shares two pins with every other I2C sensor you own — chain your climate/light/CO2 stack on one bus and mind the address clashes (this one lives at 0x68). Any ESP32 dev board works.