Project Goal

To create Arduino based device to compare data for as much t/RH sensors as possible (without manual sensor switch), optionally with data logging for further analysis.

Preparation

Use of the same sensor on i2c usually limited by 1 or 2 (using ALT i2c address) of the same type. And SHT20, SHT21, SHT25, HTU21 is actually the same type, so to be able to compare measurement there is need to use i2c multiplexer. In the case of 8 line multiplexer, there is a possibility to have 8-16 sensor of the same time to be connected with Arduino.

Sensor i2c addresses and voltages

to divide between multiplexers

Sensoraddressalt addressspecVmin-VmaxVtyp1.8v3.3v5v**
AOSONG AHT100x38 (62)0x39 (63)*pdf1.8-3.6v3.3v(question)(tick)(minus)
AOSONG AHT150x38 (62)
*pdf1.8-3.6v3.3v(question)(tick)(minus)
Senserion SHT2x0x40 (64)0x41 (65)20,21,252.1-3.6v3v(minus)(tick)(minus)
Senserion SHT3x0x44 (68)0x45 (69)SHT3x2.15-5.5v3.3v(minus)(tick)(tick)
Senserion SHT8x0x44 (68)
SHT852.15-5.5v
3.3v(minus)(tick)(tick)
Meas(1) HTU21D0x40 (64)
HTU21D1.5v-3.6v3v(tick)(tick)(minus)
Silicon Labs Si70210x40 (64)
pdf1.9v-3.6v-(minus)(tick)(minus)
Bosch(2) BMEx800x76 (118)0x77 (119)6801.71v-3.6v1.8v(tick)(tick)(minus)
Bosch(2) BME2800x76 (118)0x77 (119)2801.71v-3.6v1.8v(tick)(tick)(minus)
Ti(3) HDC10800x40 (64)
pdf2.7v-5.5v3v(minus)(tick)(tick)
Ti(3) HDC20800x40 (64)0x41 (65)pdf1.62v-3.6v-(tick)(tick)(minus)
AOSONG DHT120x5C (92)
*pdf2.7-5.5v5v(minus)(tick)(tick)
AOSONG AM23200x5C (92)
*pdf3.1-5.5v5v(minus)(minus)(tick)

1 TE Connectivity Measurement Specialties

2Bosch Sensortec

3 Texas Instruments

** some sensors board have voltage regulators and level converter (and may support voltages above mentioned in sensor datasheet)

Draft schematic

Versions

v1

v2

v3

v4 - failed

v5

v6 - unstable

v7 - current

v8