The components I used for the Data logger I have fitted in the WinLink shed.
The brain behind the logger. The ESP8266 is a small microcontroller with built WiFi. It can be programmed using Arduino IDE. It has 15 GPIO pins programmable HSPI UART and a 10Bit ADC.
Sparkfun Si7021 Temperature humidity. Uses a HSPI interface.
OLED Display 0.96" 128x64 I2C SSD1306. Not really needed but displays the current data. Connected via HSPI interface also.
The DC-DC converter supplies 5v to the micro USB connector on the ESP8266. It has a in built regulator and runs off 3.3v
The 10 bit ADC is only good for 1v input. The voltage divider Z1 8900 ohm Z2 480 ohm resisters were chosen to drop the 0v to 20v down to 0v to 1v. Different modes of the solar charger can reach 15 odd volts so I chose 20V to give some head room.
