Project Goal

To create Arduino based device to compare data for as many 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 a need to use i2c multiplexer. In the case of 8 line multiplexer, there is a possibility to have 8-16 sensor at 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 - unstable

v8 - unstable

v9 - current

v10 - abandoned

v10-AHT