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ANAVI Gas Detector

An ESP8266-powered, open source, Wi-Fi dev board for monitoring air quality and detecting dangerous gases


ANAVI, the ANAVI logo and combinations thereof, are registered trademarks of Leon Anavi. Other product names may be trademarks of others and the rights belong to their respective owners.

The information in this document is provided in connection with Anavi products. No license, express or implied or otherwise, to any intellectual property right is granted by this document or in connection with the sale of Anavi products.

This work is licensed under the Creative Commons Attribution-ShareAlike 4.0 International (CC BY-SA 4.0). this license, visit

ANAVI Gas Detector hardware design is licensed under a Creative Commons Attribution-ShareAlike 4.0 International (CC BY-SA 4.0).

The software examples are released under MIT and the rest of the software is available under GPLv3.

It is possible that the pictures in this manual differ from the latest revision of the board.

The product described in this document is subject to continuous development and improvements. All particulars of the product and its use contained in this document are given by Anavi in good faith. However all warranties implied or expressed including but not limited to implied warranties of merchantability or fitness for purpose are excluded. This document is intended only to assist the reader in the use of the product. Anavi shall not be liable for any loss or damage arising from the use of any information in this document or any error or omission in such information or any incorrect use of the product.

This evaluation board/kit is intended for use for engineering development, demonstration, or evaluation purposes only and is not considered by ANAVI to be a finished end-product fit for general consumer use. People handling the product must have electronics training and observe good engineering practice standards. As such, the goods being provided are not intended to be complete in terms of required design-, marketing-, and/or manufacturing-related protective considerations, including product safety and environmental measures typically found in end products that incorporate such semiconductor components or circuit boards.

There is no warranty for the design materials and the components used to create ANAVI Gas Detector. There are considered suitable only for ANAVI Gas Detector.

CHAPTER 1: Overview


ANAVI Gas Detector is an open source, easy-to-use, Wi-Fi compatible development board for monitoring air quality and detecting dangerous gases. It supports popular analog MQ gas sensor modules such as MQ-135, MQ-2, MQ-3, etc. Furthermore, it comes with slots for mini OLED display and up to three additional I²C sensor modules, including the precise digital sensor HTU21D for measuring temperature and humidity.

Air pollution is a very serious problem. Monitoring air quality and detecting toxic gases can improve one's quality of life. All these features make ANAVI Gas Detector appropriate for developers, makers, students and open source enthusiasts who are interested in home automation and an environmentally friendly lifestyle.

ANAVI Gas Detector is designed with the free and open source electronics design automation suite KiCAD. No soldering is required. You can assemble ANAVI Gas Detector with your bare hands and a screwdriver.

Features & Specifications

  • CPU: Tensilica L106 32-bit processor (ESP8266)
  • Connectivity: Wi-Fi 802.11 b/g/n
  • Gas sensor support: MQ-135 for air quality or any other 5 V MQ analog gas sensor
  • Peripherals: Mini OLED display, UART pins for flashing custom firmware, button, three slots for I²C sensors
  • Compatibility: Arduino IDE, PlatformIO, Home Assistant, OpenHAB, ThingSpeak, MQTT, and any modern web browser
  • Certification: Open Source Hardware Association (OSHWA) BG000018
  • Dimensions: 75 mm x 40 mm

Target Market

ANAVI Gas Detector is easy to use. You don’t need to be a tech whiz to use it. You can assemble it without any tools, and only a screwdriver is needed to mount the OLED display to the acrylic enclosure. Whether you're a newbie to home automation or a skilled engineer, ANAVI Gas Detector is a great choice for many projects.

ANAVI Gas Detector can also serve as a convenient development board for home automation. The additional slots for I²C sensor modules makes it suitable for anyone interested in Internet of Things, coding, or open source.

ANAVI Gas Detector is fully compliant with Arduino IDE, PlatformIO, the popular open source home automation software platforms Home Assistant and OpenHAB via the lightweight messaging protocol MQTT as well as ThingSpeak, the open IoT platform with MATLAB analytics. With ANAVI Gas Detector, it is easy for developers to focus on the software by easily building and flashing their own versions of the source code. Tech-savvy users can easily integrate ANAVI Gas Detector in their existing open source home automation platforms.

Board Version

Revision 1.1 of ANAVI Gas Detector was used while writing this document. It is possible that it is outdated so it is always recommended to check the latest sources from the GitHub page of the board.

CHAPTER 2: Getting Started

Electrostatic Warning

ANAVI Gas Detector is shipped in a protective bag. It must NOT be exposed to high electrostatic potentials. A grounding strap or similar protective device should be worn when handling the board. Avoid touching the component pins or any other metallic element.


In order to setup ANAVI Gas Detector the following items are required:

  • 5V power supply with microUSB

It is recommended to use 1A (1000mA) or higher power supply.

Supported Peripherals

ANAVI Gas Detector has a slot for analog 5V MQ sensor module (MQ-135, MQ-2, MQ-3, MQ-7, etc.), I2C slot for mini OLED display as well as up to 3 slots I2C sensors.


ANAVI Gas Detector supports 5V analog MQ sensor modules. The additional officially supported I2C add-on sensor modules are for:

  • Temperature and humidity (HTU21D)
  • Temperature and barometric pressure (BMP180)
  • Light (BH1750)
  • Color and gesture recognition (APDS-9960)

You may also attach any other I2C sensors but you will have to take care of their software integration.

Light Sensor

The official light I2C sensor for ANAVI Gas Detector is BH1750.

Using 4 Dupont jumper wires connect BH1750 to one of the 3 I2C slots on ANAVI Gas Detector as follows:

BH1750 ANAVI Gas Detector
VCC 3.3V

I2C External Temperature & Humidity Sensor

The official external temperature and humidity add-on sensor for ANAVI Gas Detector is HTU21 (SHT21). This is I2C sensor capable of measuring both humidity and temperature.

Using 4 Dupont jumper wires connect HTU21 to one of the 3 I2C slots on ANAVI Gas Detector as follows:

HTU21 ANAVI Gas Detector
VIN 3.3V

Color & Gesture Recognition Sensor

The official I2C sensor for RGB color and gesture detection is APDS-9960.

Using 4 Dupont jumper wires connect APDS-9960 to one of the 3 I2C slots on ANAVI Gas Detector as follows:

APDS-9960 ANAVI Gas Detector
VIN 3.3V

Temperature & Barometric Pressure Sensor

The official temperature and barometric pressure sensor for ANAVI Gas Detector is BMP180. This is I2C sensor capable of measuring both temperature and barometric pressure.

Using 4 Dupont jumper wires connect BMP180 to one of the 3 I2C slots on ANAVI Gas Detector as follows:

BMP180 ANAVI Gas Detector
VIN 3.3V


You can assemble ANAVI Gas Detector with your bare hands and a screw driver following the steps below:

  • Add sensors to your ANAVI Gas Detector.
  • Optionally, you may also assemble the simple acrylic case by removing the protective film and mounting screws.
  • Use 5V power supply and plug an appropriate cable in the microUSB of ANAVI Gas Detector to turn on the board.

Powering ANAVI Gas Detector

ANAVI Gas Detector has been tested using various 5V power supplies and USB to microUSB cables. It is recommended to use 5V power supply with 1A or higher current output. Make sure that you are using a 5V power supply from a trusted supplier. Cheap, untested power supplies can be risky and unreliable.

Configure ANAVI Gas Detector

Video tutorial for getting started with ANAVI Light Controller, same procedure for ANAVI Gas Detector

Turn on ANAVI Gas Detector by plugging an appropriate power supply. As soon as the board is turned on for the very first time it will create a temporary WiFi access point. Connect to it from your computer, smartphone or tablet.

The default software of ANAVI Gas Detector has a captive portal which guides you through the configurations. As you see in the video you have to select your WiFi network and enter a password if it is not open.

Our open source software relies on the machine to machine communication protocol MQTT to report data from the sensors. You can connect to your own MQTT broker or just leave the default configurations and connect to the public broker as shown in the video.

It very important to copy the machine ID. Later it is needed to identify your device.

When you are ready just click save. If you have entered valid credentials in a moment ANAVI Gas Detector will connect to your WiFi network and the configured MQTT broker. This way the configuration is complete and ANAVI Gas Detector will turn off its temporary WiFi access point. After that your device, for example smartphone as in the video, will automatically connect again to your WiFi network.

To verify that ANAVI Gas Detector is up and running open a modern web browser and visit Enter your machine ID. Check the advanced settings only if you are not using the default public MQTT broker. Click connect.

Reset to Factory Defaults

If you decide to change the settings of ANAVI Gas Detector you need to reset the board and configure it again.

To reset ANAVI Gas Detector press the button and hold it for 10 seconds until the red light is blinking. After resetting the board there will be a steady red light that indicates that the temporary WiFi access point is on and you can proceed with the configuration again.

CHAPTER 3: Software Development

Default Firmware

By default ANAVI Gas Detector comes with this free and open source Arduino sketch.

USB to UART Module

For uploading firmware to ANAVI Gas Detector you need USB to UART module. All kits include CP2102 which out of the box on GNU/Linux distributions. Drivers for MS Windows and Mac OS X are available at

Setting up the Arduino IDE

  1. Install the Arduino IDE following the instructions from from

  2. Add the ESP8266 board package: In File > Preferences input into the Additional Board Manager URLs field.

  3. In Tools > Board ... > Boards manager find and add the ESP8266 package. Now "Generic ESP8266" should be an option in the Tools > Boards menu.

  4. In Tools > Flash Size: select 4M (1M SPIFFS)

  5. Go to Sketch > Include Library > Manage Libraries... and include the following dependencies of the default firmware for ANAVI Gas Detector:

  • WiFiManager by tzapu (version 0.12.0)
  • ArduinoJson by Benoit Blanchon (version 5.11.1)
  • PubSubClient by Nick O'Leary (version 2.7.0)
  • Adafruit HTU21DF Library by Adafruit (version 1.0.1)
  • Adafruit APDS9960 Library by Adafruit (version 1.0.5)
  • DHT sensor library by Adafruit (version 1.3.4)
  • U8g2 by oliver (version 2.23.18)
  • OneWire (version 2.3.4)
  • DallasTemperature (version 3.8.0)
  • Adafruit Unified Sensor by Adafruit (version 1.0.2)
  • Adafruit BMP085 Unified by Adafruit (version 1.0.0)

Note: Issues might be experienced if using different versions of the libraries.

Flashing Custom Firmware

Follow the steps below to compile and flash custom firmware on ANAVI Gas Detector from Arduino IDE:

  1. To flash the firmware from Arduino IDE select Tools > Generic ESP8266 Module (Flash mode: DIO, Flash frequency: 40MHz, CPU frequency: 80MHz, Flash size: 4M, Debug port: Disabled, Debug level: None, Reset method: ck, Upload speed: 115200, Port: /dev/ttyUSB0). Set the flash size to 4M (1M SPIFFS). You might need to adjust the port if your USB to serial debug cable is connected on a different port.

  2. After that press load an Arduino sketch. A simple blinking LED example is available at GitHub

  3. In Arudino IDE click Verify/Compile (Ctrl+R)

  4. Connect ANAVI Gas Detector to the USB to serial debug board: GND to GND, TX cable to RX of ANAVI Gas Detector and RX cable to TX of ANAVI Gas Detector.

  5. In Arudino IDE click Upload (Ctrl+U)

  6. Press and hold the RESET button on ANAVI Gas Detector. Plug the 5V power supply in the jack of ANAVI Gas Detector (without releasing the RESET button).

  7. In Arduino IDE verify that the upload has been started. Hold RESET until the upload completes.

The output in Arduino IDE for successful flashing is:

Archiving built core (caching) in: /tmp/arduino_cache_954939/core/core_esp8266_esp8266_generic_CpuFrequency_80,FlashFreq_40,FlashMode_dio,UploadSpeed_115200,FlashSize_512K64,ResetMethod_ck,Debug_Disabled,DebugLevel_None_____1c2aa2b3da66da225b39c9bfab6531e5.a
Sketch uses 224949 bytes (51%) of program storage space. Maximum is 434160 bytes.
Global variables use 31756 bytes (38%) of dynamic memory, leaving 50164 bytes for local variables. Maximum is 81920 bytes.
Uploading 229104 bytes from /tmp/arduino_build_904122/anavi-blinking-led.ino.bin to flash at 0x00000000
................................................................................ [ 35% ]
................................................................................ [ 71% ]
................................................................                 [ 100% ]

If you have flashed the blinking LED example, D1 on ANAVI Gas Detector with start blinking.

Please have a look at the YouTube video that shows the exact steps for compiling and uploading an Arduino sketch to ANAVI Gas Detector.

Note: you have to be quick between step 5 and 6. Remember to press and hold SW1 until the upload completes.

OTA Firmware Upgrade

Recent versions of the official firmware also support OTA firmware updates by putting a firmare binary on a web server and then triggering the update via a MQTT message. This can be very convenient, as you do not have to connect the device to your computer.

Check support

If you are unsure if your current firmware supports OTA update, you can first check if your ANAVI Gas Detector is already setup to receive MQTT commands.

To do this, send a MQTT message to the topic "cmnd/[deviceId]/line1" with message body "test", for example using mosquitto_pub:

mosquitto_pub -h [mqttserver] -p 1883 -t cmnd/b5cfb5cfb5cfb5cfb5cfb5cfb5cfb5cf/line1 -u [mqttuser] -P [mqttpass] -m "test"

When this message causes the first line of your ANAVI Gas Detector display to change to "test", OTA updates should be supported. If not (after double checking that you used the correct topic and deviceId), please first update to a more recent firmware version.

(To reset the line again to the default display, just send an empty message to the same topic).

Build binary firmware image

Using the arduino build setting above, instead of clicking Upload (Ctrl+U), use Menu Sketch -> Export compiled binary (CTRL+ALT+S). A .bin file will be created in the same folder as the .ino file. Copy this file to an HTTP webserver, for example a server in your local network.

Trigger update

The devices listens to MQTT messages in topic "cmnd/[deviceid]/update" and expects messages to be in the format

{"file":"/[filePath]", "server": "[server IP or DNS name]"}

For example, if you put the file at

{"file":"/anavi.bin", "server": ""}

If your server does not listen on port 80, you can provide the port, for example for

{"file":"/anavi.bin", "server": "", "port": 8080}

Example for sending an update message using mosquitto_pub:

mosquitto_pub -h [mqttserver] -p 1883 -t cmnd/b5cfb5cfb5cfb5cfb5cfb5cfb5cfb5cf/update -u [mqttuser] -P [mqttpass] -m "{\"file\":\"anavi.bin\", \"server\":\"\", \"port\":8080}

Note: To ensure successful update, please specify the file with leading slash ('/'), use an HTTP web server, not HTTPS, and -- when run from the command line -- escape quote characters

On receipt of this message, ANAVI Gas Detector will download the file from the specified server, update the firmware and restart. As with the normal firmware update, your saved settings such as WiFi and MQTT server settings should remain as configured.

Note: After the update, you may find that readings from the DHT22 sensor no longer work and temperature and humidity are shown as "0". In this case, please powercycle the device (unplug power until display turns off, then plug power in again)

CHAPTER 4: Home Assistant

Home Assistant is a free and open-source home automation platform running on Python 3 with more than 1200 components for integration with popular Internet of Things.

ANAVI Gas Detector can be easily integrated in Home Assistant using the component MQTT sensor. This component supports JSON in the payload of the MQTT messages. To use, in configuration.yaml specify MQTT broker and register the sensor with the correspoding MQTT topic, for example:

  • Configure MQTT broker:
  • Register the MQTT sensor:
    - platform: mqtt
      name: "Temperature"
      unit_of_measurement: 'C'
      state_topic: "home/room/temperature"
      value_template: "{{value_json.temperature}}"
    - platform: mqtt
      name: "Humidity"
      unit_of_measurement: '%'
      state_topic: "home/room/humidity"
      value_template: "{{value_json.humidity}}"

CHAPTER 5: Schematics


The components of ANAVI Gas Detector relies on ESP8266 (ESP-12 module) and utilizes the following pins:

Component Pins Arduino Pin ID
I2C 13, 14
MQ gas sensor 2 0 (analog)
Indication LED (D1) 4 16
Green LED (D2) 7 13
Yellow LED (D3) 6 12
Red LED (D4) 5 14
Reset button (SW1) 12 0
Extra GPIO 11 2
UART 15, 16


The sensors that can be connected to ANAVI Gas Detector communicate with a host microcontroller via a communications standard called I2C (Inter-Integrated-Circut). I2C uses two wires, labelled SDA (Serial Data) and SCL (Serial Clock). To function properly, I2C requires a pullup resistor on each of those lines therefore ANAVI Gas Detector includes two 4.7kohm resistors labelled as R2 and R3. If for one reason or another you need to disable the I2C pullup resistors remove R2 and R3.

CHAPTER 6: Frequently Asked Questions (FAQ)

What power supply do I need?

You need a standard 5V power supply with microUSB connector.

Why isn't a power supply included?

We were unable to source power supplies with universal plugs for the US/EU/UK at an acceptable. Nowadays, 5V power supplies with a microUSB connector are a commodity item because of most smartphone and tables, so you should be able to easily find a suitable unit online or at your local electronics store.

Can I remotely control ANAVI Gas Detector from a web browser on my smartphone, tablet, or laptop?

Yes, you can use our demo website or easily integrate ANAVI Gas Detector in your instance of the popular open source platforms OpenHab 2, ThinkSpeak and Home Assistant as an MQTT Sensor component.

Is ANAVI Gas Detector an open source project?

Yes, ANAVI Gas Detector is an open source hardware project powered and created with free and open source software. The hardware designs are available at GitHub under CC BY-SA 4.0 license. All schematics, documents, and source code files are available at our GitHub repositories.

Is ANAVI Gas Detector certified?

Yes, ANAVI Gas Detector revision 1.1 has been certified by the Open Source Hardware Association under UID BG000018.

Does ANAVI Gas Detector use the ESP8266?

Yes, ANAVI Gas Detector is based on the ESP8266.

Can I flash different firmware to ANAVI Gas Detector?

Yes, using a USB to serial cable, you can flash custom firmware built from your own source code.

Is ANAVI Gas Detector compatible with Arduino IDE?

Yes, ANAVI Gas Detector is compatible with Arduino IDE. You can easily upload your own Arduino sketches to the board.

How can I get involved and help?

Buy any of the available perks, get your hands on the ANAVI Gas Detector, contribute to our GitHub repositories, and become part of our open source community!

CHAPTER 7: Revision History

Document Revision

Date Changes Modified pages Author
27 July 2019 Initial release All Leon Anavi

ANAVI Gas Detector Revision

Revision Notable changes
1.1 Stable product

See Also

For more information please visit and our GitHub repositories. If you have any questions or enquiries please contact us through Facebook, Twitter or email.