VINDRIKTNING ESP32

About this project

This project takes Ikea VINDRIKTNING air dust sensor in combination with LaskaKit ESP-VINDRIKTNING ESP-32 I2C, adds several sensors such as SCD41 and DHT22 (optional) or SHT40 (optional) for full measuring of air quality.

Hardware

Used hardware is mentioned above. This combination of HW sensors allows to measure following parameters:

• Amount of C02 in ppm in the air (by SCD41)
• Amount of dust in ug/m3 in the air (by PM1006K)
• Air temperature (by SCD41 or DHT22 or SHT40)
• Air humidity (by SCD41 or DHT22 or SHT40)
• Ambient light amount (by internal phototransistor)

As an output the 3 RGB led diodes are used. Also buzzer with switching transistor can be attached to alert you when air quality getting low and your room needs to be ventilated.

You can see wiring of external sensors here:

                        (optional)         (optional)
   ++==========++     ++==========++     ++=========++
   ||          ||     ||          ||     ||         ||
   ||  -----   ||     ||  -----   ||     ||  -----  ||
   ||  SCD41   ||     ||  SHT40   || OR  ||  DHT22  ||
   ||  -----   ||     ||  -----   ||     ||  -----  ||
   ||          ||     ||          ||     ||         ||
   || SCL  SDA ||     || SCL  SDA ||     ||  DATA   ||
   ++==o====o==++     ++==o====o==++     ++===o=====++
       |    |             |    |              |
       |    |             |    |              |
       |    |             |    |              |
       |    |             |    |              |
       o------------------/    |              |
       |    |                  |              |
       |    o------------------/              |
       |    |                                 |
       |    |                                 |
       |    |                                 |
       |    |                                 |
       |    |                                 |
       |    |(uSup)                           |(J3)
   ++==o====o=================================o=====++
   || IO22 IO21                              IO5    ||
   ||                                               ||
   ||              ------------------               ||
   ||              VINDRIKTNING-ESP32               ||
   ||              ------------------               ||
   ||                                               ||
   ||                    IO13           IO12  UART2 ||
   ++=====================o======= ======o=====oo===++
                          |(J4)          |     ||
                          |              |     ||
          O 5V            |              |     ||
          |               |              |     ||
   ++=====o====++         |          ++==o=====oo===++
   ||          ||         |          || FAN   RX/TX ||
   ||          ||         |          ||             ||
   ||  ------  ||         |          ||   -------   ||
   ||  Buzzer  ||        +-+         ||   PM1006K   ||
   ||  ------  ||        | |         ||   -------   ||
   ||          ||        | | 450R    ||             ||
   ++=====o====++        | |         ++=============++
          |              +-+
          o--\|  2N2222   |
              |-----------/
          o<-/|
          |
          |
         ---

Software

As base software platform have been used Micropython, as it is relatively robust, lean and easy to develop. It also allow to easily adds custom plugins in the case of need. Whole system is written using asyncio based cooperative scheduling. This concept allows following:

• Written software based on asyncio cooperative scheduling (multiple simultneouisly running tasks)
• Simple plugins framework (each plugin gets its own task)
• Access to sensors and dispatching it's values to plugins (tasks refreshing sensors states)
• Easy configuration based on configuration json files (default variants are created autoamtically when they are not present).
• Power management handling (prevent heating of processor by periodically falling to light sleep mode).
• Automatic LED intensity based on surrounding light amount and olor transition control (transition tasks).
• Access to WiFi networking (network management task allowing to connect e.g. to MQTT).

By default there are following built-in plugins:

• sensor_to_led used to set LED diodes according to current sensors state (CO2 and dust - enabled by default).
• sensor_to_mqtt used to send sensors values to MQTT broker so they can be later processed e.g. by Home Assistant or another MQTT client.
• co2_alert alerts you when CO2 amount in room reaches above certain limit.

Micropython

Install

1. Download and install python.
2. Install esptool by command pip install esptool.
3. Download precompiled Micropython firmware from this repository (all bin files are required).
4. Erase chip by following command:

esptool.py -b 460800 --chip esp32 --port /dev/ttyUSB0 erase_flash` (choose port where your device is connected - `COM`*n* on Windows)

5. Flash downloaded firmware by following command:

esptool.py -b 460800 --before default_reset --after hard_reset --chip esp32  write_flash --flash_mode dio --flash_size 4MB --flash_freq 40m 0x1000 bootloader.bin 0x8000 partition-table.bin 0x10000 micropython.bin

When all steps above succeeded, you can switch the device off and on. All python files are already built-in as frozen modules and device shall start immediatelly (there is no need to upload any python code). All configuration files are created when device boot up.

Additional tweaking

For additional tweaking we needs some UART terminal with capability to edit configuration files. We can use Thonny IDE for this purposes. To install this IDE we can use command pip install thonny. After that you can type thonny in your terminal and run it.

First of all we need to set-up IDE to be attached to micropython device. To do that go into Tools -> Options... -> Interpreter and choose Micropython (ESP32) and port where is ESP connected.

Once interpreter is set up, then click on Stop/Start backend button (or press CTRL + F2).

Then you shall be able to see python repl prompt and files stored in device.

Configuration

Once we have file system accesible via thonny, we can edit any of created json files. Files are created by default with description so it shall be obvious what, whyv and how it can be changed. You can now set-up e.g. WiFi connection, enable some defaultly disabled plugins or set their parameters.

Running modified or fixed code

All python modules are already built in as part of flashed binary, however if you feel you need to fix or modify something in code, simply upload any of modified modules (python files) to file system. When python starts it primarily search for modules on file system and when they are not found, the frozen module is loaded instead. This allow to replace any of built-in python code by your custom code without need to compile new micropython binary.

Plugins

Software is written to support core user functionality by plugins. This plugins are loaded automatically from folder plugins. Plugins are written in python and there are several plugins already present po provide some basic functionality or as some examples for those who wants to write his own (have a look into folder src/app/plugins).

sensor_to_led

This plugin handles LED colors according to sensors values. Especially CO2 (top LED) and dust (bottom LED) sensor. Colors are signalizing smoothly from green (good conditions), over blue (normal conditions) to red (bad conditions).

sensor_to_mqtt

This plugin provides sensors data to MQTT broker so anyone can use them. When plugin starts, it prints on UART template of settings for Home Assistant so you add them to you HA and can see them as regular sensors. Just note that this template is printed in debug mode only (file cfg/logging.json)

   [sensor_to_mqtt] 
   [sensor_to_mqtt] When you want to see you sensors in Home Assistant, please add following to configuration.yaml
   [sensor_to_mqtt] 
   [sensor_to_mqtt] mqtt:
   [sensor_to_mqtt]   sensor:
   [sensor_to_mqtt]     - name: "My own CO2 sensor name (please fill in)"
   [sensor_to_mqtt]       unique_id: "vindriktning_livingroom_co2"
   [sensor_to_mqtt]       icon: "mdi:molecule-co2"
   [sensor_to_mqtt]       state_topic: "vindriktning/livingroom"
   [sensor_to_mqtt]       unit_of_measurement: "ppm"
   [sensor_to_mqtt]       value_template: "{{ value_json.co2 }}"
   [sensor_to_mqtt]     - name: "My own dust sensor name (please fill in)"
   [sensor_to_mqtt]       unique_id: "vindriktning_livingroom_dust"
   [sensor_to_mqtt]       icon: "mdi:weather-dust"
   [sensor_to_mqtt]       state_topic: "vindriktning/livingroom"
   [sensor_to_mqtt]       unit_of_measurement: "ug/m3"
   [sensor_to_mqtt]       value_template: "{{ value_json.dust }}"
   [sensor_to_mqtt]     - name: "My own temperature sensor name (please fill in)"
   [sensor_to_mqtt]       unique_id: "vindriktning_livingroom_temp"
   [sensor_to_mqtt]       icon: "mdi:thermometer"
   [sensor_to_mqtt]       state_topic: "vindriktning/livingroom"
   [sensor_to_mqtt]       unit_of_measurement: "°C"
   [sensor_to_mqtt]       value_template: "{{ value_json.temp }}"
   [sensor_to_mqtt]     - name: "My own temperature sensor name (please fill in)"
   [sensor_to_mqtt]       unique_id: "vindriktning_livingroom_humi"
   [sensor_to_mqtt]       icon: "mdi:water-percent"
   [sensor_to_mqtt]       state_topic: "vindriktning/livingroom"
   [sensor_to_mqtt]       unit_of_measurement: "%"
   [sensor_to_mqtt]       value_template: "{{ value_json.humi }}"
   [sensor_to_mqtt]     - name: "My own light sensor name (please fill in)"
   [sensor_to_mqtt]       unique_id: "vindriktning_livingroom_light"
   [sensor_to_mqtt]       icon: "mdi:theme-light-dark"
   [sensor_to_mqtt]       state_topic: "vindriktning/livingroom"
   [sensor_to_mqtt]       unit_of_measurement: "%"
   [sensor_to_mqtt]       value_template: "{{ value_json.light }}"
   [sensor_to_mqtt] 

co2_alert

This plugin activates alarm on built in buzzer when CO2 level exceedes certain value to notify that is time to open window and make air more fresh.

Advices

Measuring with SCD41

Sensor SCD41 does great job and measures relatively precisely. But this is true only in certain conditions. Output of this sensor depends on how this sensor is mounted into the device. Measurement can be negatively affected by external vibration or heating or cooling. This can be in small space like VINDRIKTNING box especialy when ESP32 chip produces some heat and when area is even ventilated by PM1006K a bit problem. This is main reason why some kind of power management was implemented in this software. However to add additional molytan isolation around sensor would help. Be sure to keep side of sensor pointing out of the box uncovered to keep access to the outer air. To use some rubber mount dumpers would be good idea as well as there may be vibrations from PM1006K ventilator.

Measuring with DHT21 or SHT40

I tried to add also DHT21 and SHT40 as I was unsure about precision of measuring humidity and temperature by SCD41. However after some time I found that SCD41 gets values reliable enough, so this additional sensors are not really necessary unless you want to have precise measuring.