Bosch BME680 / BME688
Also known as: BME680 · BME688 · Air quality
Four sensors in one 3 mm can — climate plus a gas sensor that, run through Bosch's BSEC library, produces an IAQ score, eCO2 and breath-VOC estimates. The all-in-one for single-sensor environment nodes.
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At a glance
⚑ flag an error| Measures | voc, temperature, humidity, pressure |
|---|---|
| Accuracy | Gas resistance + T/RH/P; meaningful IAQ needs Bosch's closed BSEC algorithm |
| Interface | I2C @ 0x76 / 0x77 |
| Supply | 3.3 V |
| Battery-viable | No (continuous draw) |
| ESPHome | Native ESPHome component — bme68x_bsec2 |
| Typical price | $4-9 (street, varies) |
Compare all sensor modules in one table →
Which one do I buy?
vs SCD41 + SGP41 pair: the pair measures real CO2 and a cleaner VOC index for a few dollars more; the BME68x wins on size and single-part simplicity.
Clone check
Good for
Gotchas to know
- Raw gas-resistance ohms confuse everyone — you want the bme68x_bsec2 component, which needs state persistence and a ~24 h+ burn-in before IAQ is trustworthy.
- BSEC is a closed-source blob with licensing strings — pure-open builds use raw mode and live with it.
- The gas hotplate self-heats the die: its temperature reads high; offset accordingly.
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 0x76 / 0x77). Any ESP32 dev board works.