Quote:
Originally Posted by damo
Hello,
I will keep posting here as the project will advance. For now here is initial schematics.
CPU: Arduino Due
Communication: Arduino Ethernet Shield, RS485 module
Temp & Humidity sensors: DHT22
CO2 sensor: T6004
air flow sensor: MD0550
delta P: I2C sensor range 50 mbar
Comments welcome.
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damo,
Wow! You are making a very smart controller here!
I have not worked with the DHT22, I did try the DHT11 and was not pleased with the accuracy. I next tried the SHT15 humidity and temperature sensor from Sensirion and now I am so confidant in its accuracy, that it has become the standard by which I compare all my other temperature and humidity measuring instruments.
Also, regarding the T6004, I used the analog output from the T6004 to my Teensy(Arduino clone). It works very well, but from time to time I get readings that are extremely wrong, and require me to do a reset. On my thread, you will find a link to a document that explains the serial protocol for the T6004. It was a bit too complex for me, but if you can figure it out, I would like to use that approach, too.
I am interested to know how your air flow sensor works for you. I decided that I was more interested in how the fresh air flow affected the CO2 levels and humidity levels than what the air flow was. Maybe your idea is better.
Your idea to measure delta P is a very good one. How will you measure this? I ordered a pair of barometric sensors, one for indoor air pressure, one for outdoor air pressure, that should be able to resolve whether a door or window is open. This could be used to turn off the fans on the controller. It might also be possible to do this by monitoring the current draw of the fans.
I like the idea of adding Ethernet to the device, but I'm not sure how useful it would actually be. I had thought of this, but I decided that I wanted my controller to simply do its job, it did not need to tell the world what it was doing. I admit that, in the past, I have been lacking in vision.
Good luck with your project, take lots of photographs, that really helps other people understand what you are doing.
Sincerely,
AC_Hacker