In this article you will find a tutorial on how to build a air quality analyser. The analyser is dedicated to be put on a car as it travels so that we can build an online database gathering all the informations on air quality by location.
In order to realized it, we used the following hardware items :
- STM32 : NUCLEO-N432KC
- multichannel gas sensor : Grove 101020088
- optical dust sensor - GP2Y1010AU0F
- humidity and temperature sensor : DHT11
- wisol module : SFM10R1
And the following softwares :
Step 1: Code Development
First of all we used Mbed to develop the code for each component independently.
For the multichannel gas sensor, optical dust sensor and the humidity and temperature sensor we used the sensors' libraries and simply use the functions that translate raw datas into exploitables datas.
For the dust density sensor we needed to light the internal LED for 0.32ms and read the value 0.28ms after it was turned on and then switch off the LED for another 9.68ms.
After testing each sensor we reunited all the codes in one in order to obtain all the measures printed.
Once the datas are gathered, they are translated into integer so that they can be coded in hexadecimals to be sent on the Sigfox network. Then we implemented the Wisol module to establish the communication with the Sigfox network.
Step 2: Sigfox - DataBase
Once the datas are received by Sigfox, thanks to defined callbacks, they are redirected towards our Ubidots database. There we can check the evolution of every measures over time.
Step 3: PCB
Once the card is functional on LABDEC, it was necessary to transfer it to a circuit board PCB. For this purpose several software and platforms are available to do so. We have used Altium software for its simplicity and efficiency. Altium offers PCB schema creation and print and solder with components.
Here we explain in several steps the tutorial of the creation of the electronic circuit.
STEP 1 : The creation of the schema.
First of all, you must download the libraries that allow you to obtain the nucleo card, it is available in the link : https://github.com/EEEManchester/Altium-Stuff/tre...
You can then create the schema by adding the NUCLEO and connect it to the components, GPS, Gas Sensor ...
STEP 2 : Conversion to PCB
Convert your PCB schema into a real PCB. When it's done, put the components and the NUCLEO so that it's the easiest to wire, the connection cables must cross as little as possible.
This method will ensure that only one layer of wiring is used. preferably the lower layer, (it is better to increase the size of the connections to 50mil in order to have no break or lack of electrical fluidity) .
STEP 3: Printing of the PCB.
Once steps 1 and 2 are over, you will have this window on your Altium project.
Then you must create a Gerber Files, this step is detailed in the link : https://drive.google.com/drive/folders/0ByJoYAHOf...
Step 4: Assembly
Finally, after soldering the plug connectors we put our circuit into a box letting the sensors on the outside so that they stay in the ambient air.