AetherPhylax

Tiny Energy Harvesting Environment Monitior

Hardware Desctiption:

• uC: STM32G071
• LoRa Module: RFM95
• power management: BQ25570 (<5.5V)
• I2C
• 1 GPIO: (PA0 (int0))
• JST ZH 1.5mm connectors
• 1.27mm header for for programming and debugging (SWD+UART)

Detailed Description

It's centered around a STM32G071 microcontroller and uses LoRa for efficient and longish range communication. Currently it sends to a custom Gateway which forwards the data to a MQTT server but the code can be easily adapted to use another LoRa infrastructure like The Things Network. The LoRa Module is a RFM95.
A 18650 cell (other Li Ion batterys can be used too) is used for power which is charged by a TI BQ25570 which harvests energy from a solar panel. The uC can read the solar and battery voltage.
There is 1 GPIO available (PA0 (int0)) and a I2C bus. The GPIO has a footprins for a pull-up/-down resistor or capacitor and 3V3 and GND connections next to them. JST ZH 1.5mm connectors are used and a 1.5mm pinout is present for programming and debugging (SWD+UART).

Software Description:

The project is written in Arduino.
Each Station has it's own name so multiple can be used on a single Gateway. The station wakes up in specified Intervalls (2min) and checks if any of the sensor values have changed, if so it sends the data as a JSON to the Gatway. The data is send every 10th wakeup no matter the values as a heartbeat. Currently

• Bosch BME280
• Sensiron SHT31
• Lacrosse TX23
• MaXIM DS18B20
• generic simple rain sensor are implemented an can be enabled by uncommenting code.