AQIX ESP32C3 - Air Quality Monitor IoT Weather Station

Following on from the original popular CWX (Compact Weather Station), a number of improvements have been on the shopping list for a while and one of those to add an Air Quality CO2 Sensor.

Alongside the CWX updates, this nurtured a new board, AQIX ESP32C3 (Air Quality Monitor IoT Weather Station) SDK.

Firstly was to make some top level improvements and these were:

• New ESP32-C3 MCU (replacing the ESP8266/ESP12S)
• Type C USB Interface (the old Micro USB is so yesterday)
• Improved LDO Current assisting any External Devices
• On-Board ESP32-C3 D1 UART Interface
• On-Board EEPROM for Data Logging and Configuration
• User Button
• RGB LED
• Added Dallas OneWire Interface
• Added I2C External Interface
• Improved Light Sensor
• On-Board 32.768 kHz XTAL for Real Time Clock

The New Board

As you can see from the below, the layout keeps roughly the same layout theme, as it seems to work well, with the added above cool features and a sprinkling of fairy dust, namely the SCD40, or SCD41, High Accuracy CO2 Sensor.

Configuration options on the bottom,

Overview

AQIX Preliminary Features:

AQIX is a compact, self-contained CO2 Air Quality Sensor with the addition of a range of Barometric Weather Sensors.

Based on the new Espressif ESP32C3 Mini, which has both Wi-Fi and BT, the AQIX SDK board is provided with onboard Battery Holder or External DC Input.

Interface for programming, and development, is thought a standard Type C USB, into the onboard UART and ESP32C3, so making development and use, completely self-contained.

Using the provided I2C interface, an OLED display can be plugged directly into the board, if required, for local monitoring and status information.

Opensource AQIX Firmware is provided on our GitHub, using the standard PlatformIO platform. This monitors Barometric Pressure, Temperature, Humidity, Light Level and CO2 Air Quality information, which can then be sent to your Home Automation, or cloud service, via provided MQTT or Domoticz etc., as standard.

AQIX Specification and Features

· Sensors Included

• High Accuracy CO2 Sensor SCD40 ±50 ppm + 5% of reading @400-2000 ppm Optional SCD41 ±40 ppm + 5% of reading @400-5000 ppm SCD40 ±50 ppm + 5% of reading @400-2000 ppm
• High Accuracy Barometric Sensor - Bosch BME 280 Module, providing: -
• Barometric Pressure 300...1100 hPa (millibar) - Accuracy ±0.25% - which is equivalent to 1m at 400m height change - RMS Noise 0.2 Pa - which is equivalent to 1.7 cm -
• Temperature -40 to 85°C - Temperature coefficient offset ±1.5Pa/K. - which is equivalent to ±12.6cm at 1 °C temperature change -
• Humidity - 0 to 100 % - Accuracy tolerance ±3% relative humidity - Hysteresis ≤2% relative humidity
• Ambient Light Sensor
• SFH2440, providing spectral sensitivity adapted to human eye sensitivity
• Std. Light A; T = 2856 K Minimum 7 nA/lx
• Spectral range of sensitivity λ10% typically 400 to 690 nm
• Wavelength of max sensitivity λS max typically 620 nm
• MCU Espressif ESP32-C3 Mini - 2.4GHz Wi-Fi (802.11b/g/n) and Bluetooth 5
• ESP32-C3-MINI-1-N4 (PCB Antenna)
• ESP32-C3-MINI-1U-N4 (External Antenna via U. FL cable)
• On-Board 32.768 kHz XTAL for Real Time Clock

· Type C Programming / Debug

• Type C USB Connector
• CH340K USB UART 2Mbps Transceiver
• Easy programming. Select ‘ESP32C3 Dev Module’
• BAUD rate up to 921600 to speed up Flashing
• Serial Monitoring Debug and Remote Logging
• Power Can Be Taken from USB 5V (when Flashing)

· EEPROM (I2C)

• AT24C64 64Kbit
• On-board Data Logging
• On-board Parameters
• Firmware setup user parameters and configuration

· Battery or External DC Operation

o Powered by:

• 1 x CR123 Lithium battery
• External DC such as USB 5V or 4.5 to 15V DC

· Battery Voltage Monitor

• ADC provides battery voltage reading

· External DC Input

• AMS1117 LDO allowing use of external DC input 4.5V to 15V

· External Temperature

o Dallas OneWire Interface for External Temperatures

• Example Probe Sensor for Greenhouse

· RGB LED - Status

• Configured to three GPIO’s for easy Firmware control

· I2C OLED Connector

• Configurable 3V3 Pin 1 and 2 polarities
• PCB 4 Pin Header Connector

· Buttons

• Reset
• User (Program or GP9 Detect)

· Enclosure

• Designed to fit into a Waterproof Clear Cover Enclosure

· Compact Design and Easy to Use

• Compact PCB 63mm x 51mm
• 4 x M3 mounting holes
• Operating Ambient Temperature -10 to +60 °C
• Optional Conformal Coating – on request.

· Ordering

• Boards are due in stock during October 2024. Details to follow.

o Four Versions are planned.

• Phase 1 (October 2024)
• ESP32-C3-MINI-1-N4 (PCB Antenna) & SCD40
• ESP32-C3-MINI-1U-N4 (External Antenna via U. FL cable) & SCD40
• Phase 2 (Cira December 2024) - Subject to interest
• ESP32-C3-MINI-1-N4 (PCB Antenna) & SCD41
• ESP32-C3-MINI-1U-N4 (External Antenna via U. FL cable) & SCD41

Further Information

Additional information, and other technical details on this project, maybe found in the related repository pages.

Repository Folders

• Code(Code examples for Arduino IDE and PlatformIO)
• Datasheets and Information(Component Datasheets, Schematics, Board Layouts, Photos, Technical Documentation)
• Certification(Related Repository Project or Part, Certification Information)

Repository Tabs

• Wiki(Related Repository Wiki pages and Technical User Information)
• Discussions(Related Repository User Discussion Forum)
• Issues(Related Repository Technical Issues and Fixes)

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Dave Williams, Maidstone, UK.

Electronics Engineer | Software Developer | R&D Support | RF Engineering | Product Certification and Testing | STEM Ambassador

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