Project Goal

Create arduino 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.

...

Sensor i2c addresses and voltages

to devide divide between multiplexers

Sensor	address	alt address	spec	Vmin-Vmax	Vtyp	3.3v	5v**
AOSONG AHT10	0x38 (62)	0x39 (63)	*pdf	1.8-3.6v	3.3v
Senserion SHT2x	0x40 (64)	0x41 (65)	20,21,25	2.1-3.6v	3v
Senserion SHT3x	0x44 (68)	0x45 (69)	SHT3x	2.15-5.5v	3.3v
Senserion SHT8x	0x44 (5868)		SHT85	2.15-5.5v	3.3v
Meas(1) HTU21D	0x40 (64)		HTU21D	1.5v-3.6v	3v
Silicon Labs Si7021	0x40 (64)		pdf	1.9v-3.6v	-
Bosch(2) BMEx80	0x76 (118)	0x77 (119)	680	1.71v-3.6v	1.8v
Bosch(2) BME280	0x76 (118)	0x77 (119)	280	1.71v-3.6v	1.8v
Ti(3) HDC1080	0x40 (64)		pdf	2.7v-5.5v	3v
AOSONG DHT12	0x5C (92)		*pdf	2.7-5.5v	5v
AOSONG AM2320	0x5C (92)	0xB8 ?	*pdf	3.1-5.5v	5v

...

² Texas Instruments

³ Bosch Sensortec

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

Draft schematic

Image Added

Versions

v1

• Single multiplexer breadboard draft project with 26 Sensors

...

• Use 3+ multiplexers to include twice more sensors (incl. hdc1080 and Si7021, SHT85)
• Add more SHT85 sensors to see results repitability (for most expensive sensor)
• remove some libraries (multiplexor, sensor reading) not compatible to multiple mux projects
• substitute i2c scan every cycle with pre-defined aray proccessing
• (Hardware) i2c 3.3v/5v level converter
• (Hardware) 2500mAh battery with related circuits
• (Hardware) New case, 
• (Hardware) New 2m wire between main unit and the board
• (Hardware) New plastic shields for connectors

Plan

v4

• New type of sensor: AHT10 (both wiring and code needed)
• Change board wiring for new Adafruit sensors
• replace DHT12 with additional BME280
• Wire new additional 5v sensor board with mux#4
• ? Change board sensors (HDC1080 to HTU21d)
• ? Move HDC1080 to 5v additional board
• New type of sensor: DHT22 (both wiring and code needed)
• ?
• Power one of  multiplexers by 5v to add DHT22 to test.
• data visualisation

v5

• add non-i2c sensors like DHT11 and AM2302
• make some additional screen modes and control buttons

...