RoadTest: Sensirion Gas/Temp/Humidity Sensor Kit
Author: MDeGrauw
Creation date:
Evaluation Type: Development Boards & Tools
Did you receive all parts the manufacturer stated would be included in the package?: True
What other parts do you consider comparable to this product?:
What were the biggest problems encountered?: The board is piggyback based for certain Arduino boards and works fine. Be cautious the board connects upside down. For other types you need a fly-lead cable and that would be appreciated to be included.
Detailed Review:
First of all I want to thank Element14 and Sensirion for the possibility to test the Sensor Shield.
Unpacking
The Environmental Sensor Shield arrives in a nice green box with little to no overhead room to protect the environment.
Included in the box there is a small card with instructions and a link to the appropriate location on the Sensirion website.
The Sensor Shield itself was nicely packed in a resealable ESD-protective bag which makes it easy to repack and store it after use.
The Hardware
The shield contains 2 sensors, 3 LEDs and preferential components as the sensors work at voltages below 3.3V.
LED1 red, LED2 yellow and LED3 green to make indications possible.
Interfacing the board is both possible with 3.3V and 5V controller boards.
This makes it easy to use as no additional level-shifting is needed to use it in a R&D or educational environment.
Both sensors are clearly marked, LEDs have marking to the connected pins. Also there is are both written and QR-code indication to the designated developer website.
Connecting the Shield to an Arduino is easy as it has the pin-out compatibility, BUT don't be fooled by the printing on the board.
When connection the Sensorboard to the Arduino you will become aware that the text will not read in the same direction.
For example I used an Arduino MEGA R3 so keeping the USB/power socket to the left you can read the imprints on the Arduino, now when stacking the Sensor board make sure the text reads upside down. There is no direct marking on the sensorboard to make sure someone will turn it the right way. As the board has some fiducial near the connector, some might be mistaken to see these as markings for the lower connector.
Installing and usage
Following the instructions on Sensirion developers website gives you enough instructions to get started with installing the required libraries and examples.
The examples are properly documented and have clear comments. The various examples give you some insights what you can do.
After using the examples you get a good idea of the possibilities of the ESS module.
At the Sensirion website you can find all necessary datasheets and additional information on the sensors equipped.
For the SGP3x there is also a document that explains how to use the TVOC measurements.
Reading the document gives you good information how to implement the sensors and their returned data in projects and measurements.
Small testing project
After trying the examples and reading the documents I thought it was time for some real-life testing.
Without changing the libraries and compromising the the baselevels in the sensors it's possible to make a nice Indoor Air Quality (IAQ) tool.
I wrote an Arduino program which will be added as Attachment.
The LEDs shows in 5 steps the IAQ levels calculated as there are only 3LEDs I created additional levels by driving 1 or 2 LEDs at the same time.
As it is for testing the Air Quality in the home we can use the complicated air mixture mentioned in the document for TVOC measurements.
The conversion then results in 1ppbv equals 4.5ug/m3 for IAQlevel
Using the IAQ Levels by German Federal Environmental Agency we will get the following table
The Serial output gives you the values measured or calculated and can be used for viewing or sent to a home automation project.
Conclusions
The ESS is easy to use and serves several purposes.
The Absolute Humidity that's needed for more complicated matters can be calculated in several ways, in this case I used the near approach calculation.
For the real complicated one you need to have a Barometric sensor implemented, but for home/office IAQ applications this is not needed.
Looking at the board the Price vs Quality is real good sensors are not located near heated components and makes the measurements reliable.
Open for suggestions and comments on code and review
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