Septa Sense

Septa Sense in an Open Source and Open Hardware IoT air quality sensor, based on an ESP32 running ESPHome. It features a rim of RGB-LEDs around the top which indicate the quality of the air. Measurements can be seen either on in the integrated display or over Home Assistant. The unit is powered with a USB-C plug on the backside.

Capabilities

• Temperature (0 - 50°C ± 0.5°C)
• Humidity (0 - 100% ± 4.5%)
• VOC (1 - 500 Index ± 5 Index)
• NOx (1 - 500 Index ± 10 Index)
• Particulate Matter (0 - 1000 μg/m³ ± 10%)
• CO2 (400 - 5000 ppm ± (40 ppm + 5%))
• Pressure (300 - 1250 hPa ± 0.5 hPa)

Sensors

• SEN55
• SCD41
• BMP388

Mainboard

The mainboard is a custom PCB which holds the ESP32 chip, the BMP388 and SCD41 sensors and the RGB LEDs. The SEN55 sensor and the display are connected to it with a cable that is directly soldered to the board. It gets power via the USB-C plug over a cable with a JST XH connector that is mounted on the PCB.

3D-Print

The case consists of 5 different 3D printed parts. Recommended print settings are:

• Case Bottom
  • Layer height: 0.2 mm
  • Infill: 10 %
  • Support: Yes
  • Support overhang: 80°
• Case Top
  • Layer height: 0.2 mm
  • Infill: 10 %
  • Support: No
• LED Ring
  • Layer height: 0.2 mm
  • Infill: 20 %
  • Support: No
• SEN55 Bracket
  • Layer height: 0.1 mm
  • Infill: 20 %
  • Support: No
• Display Fixture
  • Layer height: 0.2 mm
  • Infill: 20 %
  • Support: No

BOM

• 1x Mainboard
• 1x SEN55
• 1x SCD41
• 1x Display SD1306 128x64
• 1x USB-C Connector
• 1x Micro JST GH 6 pin Cable
• 1x JST XH 2 Pin Cable
• 1x Dupont Female 4 pin Cable
• 2x M3x5,7-OD 4,6 heat inserts
• 2x M3x10 countersunk screws
• 1x Set of 3D-Prints