Environmental sensors provide a fairly simple ways to collect a variety of different data about the environment, for example air quality measurements using particle counters, CO, CO2 or O2 sensors and more basic humidity and temperature. Sensors are – depending on model – available as analogue or digital sensors with different protocols.
Temperature / Humidity
The list below presents a small collection of common, cheap digital sensors
Sensors and specifications
| AM2302 | AM2320/AM23212 | SHT71 | HTU21D | SI7021 | BME280 | |
|---|---|---|---|---|---|---|
| Operating range | 0-100 | 0-100 | 0-100 | 0-100 | 0-100 | 0-100 |
| Absolute accuracy | ||||||
| (%RH @ 25°C) | ±3% (10-90%) | |||||
| ±5% (<10%, >90%) | ±3% (10-90%) | |||||
| ±5% (<10%, >90%) | ±3% (20-80%) | |||||
| ±5% (<20%, >80%) | ±3% (20-80%) | |||||
| ±5% (<20%, >80%) | ±3% (0-80%) | |||||
| ±5% (>80%) | ±3% (20-80%) | |||||
| Repeatability | ±0,3% | ±0,1% | ±0,1% | - | ±0,025% | - |
| Long term stability | 0,5% p.a. | 0,5% p.a. | 0,5% p.a. | 0,5% p.a. | 0,25% p.a. | 0,5% p.a. |
| 1/e Response | 5s | 5s | 8s | 5s | 18s (with cover) | |
| 17s (without) | 1s | |||||
| Supply voltage | 3,3 - 5V | 3,3 - 5V (AM2320) | ||||
| 2,6 - 5V (AM2321) | 2,4 - 5V | 1,5 - 3,3V | 1,9 - 3,3V | 1,7 - 3,3V |