This project is about simplest possible weather station based on WeMos D1 Mini.
I choose WeMos D1 Mini, because it has benefits:
1. you can programme and run it without connecting externall modules, just using USB cable.
2. you dont need voltage regulator, on board is internal regulator
3. current consumption of wemos d1 mini is 0,25 mA (deep sleeping). Not bad.
4. Plug and Play concept. Wemos is similar hardware as Arduino UNO, and in my project, even breadboard is not necessary.
Step 1: BOM
1. Board. Wemos D1 Mini board (+ pins) cost 2.52 $
2. USB cabel for programming Wemos board 0.55 $
3. Battery. 18650 Lithium - ion battery. 3.04 $
4. Holder for 18650 battery 0.25 $
5. Sensor. You can choose anything, I like I2C sensors, I choose light sensor MAX44009 2.29 $
6. Cables. I choose dupont cables female to male. 0.99 $
Total: 9.64 $
7. Case. I use plastic box for testing.
8. For protect light sensor, I find glass hemispehere cca 1.5 - 2 $
9. Epoxy glue for paste glass hemispehere to case.
Step 2: Wiring
Here is simple circuit. You can connect Li - Ion battery to 5V, Wemos works. It's works!
Also you must connect D0 pin with reset pin on Wemos, to awake Wemos during sleeping.
MAX44099 - WEMOS D1 MINI
VIN - 3V3
GNG - G
SCL - D1
SDA - D2
Battery - WEMOS D1 MINI
+ to 5V
- to G
WEMOSD1 MINI - WEMOS D1 MINI
D0 - RST
Step 3: Code
I using ThingSpeak for sending data and making graph. Dont forget for deep sleeping mode for wemos and
library WiFiConfig.h to prevent wemos chip from damaging.
Step 4: Conclusion
WeMos D1 Mini is good solution for making weatherstation. My solution is clear work, without any necessary resistors and regulator as barebone ESP8266 module need and it cost less then 10 $. WeMos D1 Mini consupt 0,25 mA current (deepsleep), but with good solar cell, battery charger and good Li-Ion battery it will works.