This sensor use the BMP280 chipset to measure Temperature / Pression and Humidity
Parts :
- Wemos ESP8266 emmbeded board,
- BMP280 I2C Module
- 3,3 regulator
- 2 lipo 3,7V Batteries - 3000 mAh
The original design device looks like this :
in this device, we used :
- an ESP 8266 for wifi connection
- the BME/BMP280 module using the myMQTTIoT lua stack
this module is a wrapper to https://github.com/avaldebe/AQmon BMP 280 module
As it is powered by a battery, saving the battery is important, we connect the GPIO 16 to RST pin, permitting to deepsleep mode the chip
so we have measures on 20s every 10 mins (initially configured).
Measuring the consumption is about : 70-80 mA in measuring the air down to 5mA in sleep mode for 10 mins
battery lifetime is by now about a week.
Added a Lithium Ion protection card for avoid crash the battery (if battery is too low, it is destroyed by chemical modifications). Added an external DC - DC converter for charging phase
Latest tests show that using the hibernate mode if ESP 8266, and 15 mins wakeup for 5 measures , the batteries charge life is about 15 days.
