Solar powered Particle Photon environment monitor

Here is the Photon code and hardware details to build a solar powered environment monitor. It uses a combo module of 3 separate sensors that are read via I2C protocol to periodically measure and record:

• Temperature
• Humidity
• Light level
• Air pressure
• Battery charge

The 3 sensors are:

• HTU21D - Temperature and humidity sensor.
• Bosch BMP180 - Digital barometric pressure and temperature sensor.
• Rohm BH1750FVI - Ambient light sensor.

After the measurements are taken the values are sent to Dweet. The Photon then measure its own battery level and will deep sleep for a variable amount of time between measurements in order to conserve battery life. The sleep time will be longer when the battery gets low.

The following libraries are used:

• https://github.com/amcewen/HttpClient
• https://github.com/sparkfun/Photon_Battery_Shield
• https://github.com/adafruit/Adafruit-BMP085-Library
• https://github.com/sparkfun/SparkFun_HTU21D_Breakout_Arduino_Library/

Hardware

• Particle Photon.
• SparkFun Photon Battery Shield: Used to charge the battery from the solar panel and read the battery charge level.
• 5V 500mA 2.5W 140x140mm Solar panel: Purchased from eBay.
• HTU21D/BMP180/BH1750FVI combo sensor: Purchased from AliExpress. Some examples here.
• Polymer Lithium Ion Battery 400mAh.

The pin connections are very simple as there is only one way to connect the battery, solar panel and sensor (just uses standard I2C pins).

Photos