Datasheet: http://www.ti.com/lit/ds/symlink/hdc2080.pdf
Programming HDC20x0: http://www.ti.com/lit/an/snaa312/snaa312.pdf
aliexpress 4$ (alternative tindie 13$)
Source code example: https://github.com/tinkeringtech/HDC2080_breakout
Sensors test example: Test 4 v6 Saturated NaCl solution