Schematics.md

Schematics

All electronic components except SPS30 and Li-Pol are soldered to the prototype board. To fit inside the case the board shall be cut from the top right corner to leave 9x12 soldering holes area and one mounting hole.

The Beetle C3 controller is soldered on top close to rear side. BME280 module is soldered vertically using L-shape pins at the front side. Switch and step-up modules are soldered at the bottom. The connections are made using thin insulated wires.

• SPS30 sensor connection cable:
  • VCC is connected to the +5V output of the step-up converter
  • RX is connected to the IO21 on the Beetle C3
  • TX is connected to the IO20 on the Beetle C3
  • SEL is not connected
  • GND is connected to the GND on the switch module
• BME280 connection:
  • SDA is connected to the IO1 on the Beetle C3
  • SCL is connected to the IO0 on the Beetle C3
  • GND is connected to the GND on the switch module
  • VCC is connected to the 3V3 output on the Beetle C3
• Pololu 2810 switch connection:
  • GND 1 of 4 holes is connected to the GND pin of the C3 board, the others and used as the ground for the other parts
  • On is connected to the IO7 pin of the Beetle C3 board
  • VIN is connected to the Vbat of the Beetle C3 board
  • VOUT one hole is connected to the + input of the step-up converter. The second hole is connected to voltage divider (R1=220k, R2=330k) with the middle point's connected to the IO4 pad of the Beetle C3.
• step-up converter connection:
  • Vin hole is connected to the VBAT pin of the Lolin32-lite board
  • GND hole is connected to the GND pin of the Lolin32-lite board
  • Vout hole is connected to the VCC pin of the SPS30 sensor.
• microUSB socket connection:
  • 'GND' to the 'GND' pad of the Beetle C3
  • 'VCC' to the 'Vin' pad of the Beetle C3

The stl files:

PMSensorFrameExternalDFRobot.stl - main frame

PMSensorCoverExternalDFRobot.stl - external cover

The assembled device:

The top view on main assembly: The bottom view on main assembly: Pre-assembled parts