...second part...more tutorials...
Saludos
...third part...some vids....and....on other things...
http://www.kandrsmith.org/RJS/Misc/hygrometers.html
...great info on this web about hygrometers ...thanks bro Robin...... but i saw an "economic" Sht21 hygrometer module on some vids on youtube...
...notice in the next vid....the I2C conection matches for some displays and other curious modules...you know what i mean...
...not only hygrometers...
...the oled display module its I2C (ONLY 4 WIRES ..2 FOR DATA ...2 FOR POWER)...
...the temp / humidity SI7021 / SHT21 module its I2C too...(its more economic than sensirion and use the same chip)
...the rtc ds3231 module its I2C too...
note...Because
SD Cards require a lot of data transfer, they will give the best performance when connected up to the hardware SPI Pins on a microcontroller.
The hardware SPI Pins are Much Faster than 'bit-banging' the interface code using another set of Pins...... spi have more wires (pins) to conect...
...add an esp8266 board to the previous vid to substitute the arduino chip..mix an batery on the mix and... well i hope you or other bro catch my crazy ideas....for autonomous sensors style boards...
Saludos