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Temperature or Temperature & Humidity?


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Poll: Temperature or Temperature & Humidity? (41 member(s) have cast votes)

On a Temperature Sensor how important is Humidity sensing?

  1. 1 (Not Important) (5 votes [12.20%])

    Percentage of vote: 12.20%

  2. 2 (1 votes [2.44%])

    Percentage of vote: 2.44%

  3. 3 (Nice) (13 votes [31.71%])

    Percentage of vote: 31.71%

  4. 4 (15 votes [36.59%])

    Percentage of vote: 36.59%

  5. 5 (Very Important) (7 votes [17.07%])

    Percentage of vote: 17.07%

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#1 Arron Chapman

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Posted 06 September 2012 - 07:05 PM

We've run into some issues with some of the senors we've evaluated and would like to get a better feel for what the community would like to see from a Temperature Sensor Module.

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#2 Lunddahl

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Posted 07 September 2012 - 10:42 AM

The ideal Temp sensor module for me is a module that has one internal temp sensor, and x external temp sensors. The external temp sensors should be able to use wires up to 2-5 meters. With x i mean as many as the micro can handle, i can perfectly see applications where 8 temp sensors would be usable. The sensors should not need calibration (digital sensors), and could be using one, two or tree wires or more wires, a standard Catecory 5 twisted pair cable could be used for long cable runs, so the number of wires does not matter much. The sensor itself should me (very) small, and you should be able to fit it on the end of the cable and put it into wet consitions, but that could be up to the module user to thinker that out. Applications could be solar heaters, chemical experiments, anything where you compare different temperatures. - Ulrik Lunddahl

#3 JerseyTechGuy

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Posted 07 September 2012 - 11:36 AM

An ideal temperature sensor module should come in two varieties. It would be nice to have a module with an onboard temp/humidity like the SHT11 or SHT15. Having both temp and humidity in one package allows for calculation of dewpoint. second would be a module with an external probe that also can do both humidity and temp. Another optional, but more expensive module could be a complete Temp/Humidity/Barometric Pressure sensor package. Using something like the SHT15 and the BMP085. I think these would all work well for the everyday hobbyist or developer.

#4 Paulo Norberto

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Posted 13 September 2012 - 11:33 PM

My ideal temperature sensor module should be a module with an external probe that could be immerse in salt water. It will read the water temperature of my reef aquarium.

Something like this probe:
TempSensor (not with the 1-wire because it is not supported in the netduino hardware)

Even better if encapsulated in glass as those PH and ORP probes:
PH
ORP

BTW, PH and ORP modules are in development for a near future?
Thank you.

Paulo Norberto

#5 Nevyn

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Posted 30 September 2012 - 05:28 PM

We've run into some issues with some of the senors...

And here is one (DHT22 Temperature and Humidity sensor) finally working on breadboard:

http://www.youtube.com/watch?v=eF-dbn-b0wM

The video starts by looking at the temperature and humidity readings on a cheap domestic module purchased from Amazon. The temperature reading looks like 20.6C on the internal sensor and 20.3C on the external sensor with a relative humidity of 67%.

Moving on there's a rather fuzzy look at the voltage coming from a LM35 temperature sensor displayed on the scope. The LM35 is sitting on the breadboard beside of the DHT22. This is giving a scope reading of 208mV which translates to 20.8C.

The final part of the video shows the reading from the DHT22 shown on the Komodex Labs 4 digit seven segment display. This confirms the reading of 20.8C and gives a humidity reading of 64.7% which looks to be in the right area.

Now, where to next...

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#6 Fabien Royer

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Posted 30 September 2012 - 06:08 PM

Hi,

If you'd like to monitor temperature and humidity, you can do it today with the Nwazet DAQ and sensor drivers we provide for it:
Source code for the drivers: https://bitbucket.or....Go.DAQ/Sensors

If you have specific needs, don't hesitate to let us know: we're developing more drivers for common I2C sensors to add to the library.

Here's a sample using the Honeywell temperature and humidity sensor:


using System;
using System.Threading;
using Microsoft.SPOT;
using Microsoft.SPOT.Hardware;
using SecretLabs.NETMF.Hardware.NetduinoGo;
using Nwazet.Go.DAQ;
using Honeywell;
namespace Tutorials {
    public class I2cCommunications {
        public static NwazetDAQ daq = new NwazetDAQ();
        public static void Main() {
            daq.Initialize(GoSockets.Socket1);
            try {
                var hih = new HIH613x(daq.I2cPort);
                hih.Read();
                Debug.Print("Temp: " + hih.TemperatureCelsius + " Celsius");
                Debug.Print("Humidity: " + hih.RelativeHumidityPercent + " %");
 
            } catch (I2cException e) {
                Debug.Print("I2C transaction failed: " + e.Message);
            }
        }
    }
}


#7 Matt Isenhower

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Posted 30 September 2012 - 06:35 PM

The final part of the video shows the reading from the DHT22 shown on the Komodex Labs 4 digit seven segment display.

Nice video, Mark, thanks for sharing! :)

By the way, in the Module Drivers Source Code and Examples package, I include an extension method called SetTemperatureDisplay (in ModuleTestApp/SevenSegmentDisplayUtilities.cs). This extension method uses the apostrophe as a "degrees" symbol and allows you to specify a "C" or "F" to be displayed as the last digit.

Looks like there's a breakout module down there on your breadboard as well :D Cool stuff!

Matt
Komodex Labs
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#8 Nevyn

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Posted 30 September 2012 - 06:42 PM

Looks like there's a breakout module down there on your breadboard as well :D Cool stuff!

That breakout module is heavily used :)

Regards,
Mark

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#9 pdii

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Posted 30 September 2012 - 06:57 PM

And here is one (DHT22 Temperature and Humidity sensor) finally working on breadboard:
...
Now, where to next...


How soon till I can buy these? ;)

#10 Arron Chapman

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Posted 30 September 2012 - 07:27 PM

Mark,
Nice work hopefully we'll be able to get the PCBs put together quickly and we can get some prototypes out in the world.

How soon till I can buy these? ;)


After about 6 3 more steps ;) Be sure we'll keep you up to date on when and where you can buy one.

Visit the official Wiki! If you can help make it better please do!
When you talk EE use small words, I'm just a Software Developer :)
My Module Store, including the ProtoModule My Blog/Site and Everything Else

If my post helped you please consider pressing the "Like This" button in the bottom right hand corner.

 

Oh my. So many things, so little money!!

 


#11 Jack Chidley

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Posted 30 September 2012 - 11:08 PM

Something itched about this question. I scratched. Ahhhh... I think it's the exclusion of another option. The humidity sensor by itself. Are there occasions when just knowing humidity is useful? Or would you always want temperature too? Because I could see that having a choice about what to measure (temp or humidity or both) would be helpful. So I'd say: temperature - yes humidity - yes both - only if you can do it much cheaper than buying both of the above. Jack

#12 Arron Chapman

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Posted 30 September 2012 - 11:22 PM

Something itched about this question. I scratched. Ahhhh...

I think it's the exclusion of another option. The humidity sensor by itself. Are there occasions when just knowing humidity is useful? Or would you always want temperature too? Because I could see that having a choice about what to measure (temp or humidity or both) would be helpful.

So I'd say:
temperature - yes
humidity - yes
both - only if you can do it much cheaper than buying both of the above.



You bring an interesting point, I did do some research into doing 2 separate modules (temperature and humidity) for very low cost (Goal was ~$5) and it's not impossible. However there are 2 problems I had which led to me not wanting to go that route.
  • I have a hard time seeing users not wanting Temperature along with Humidity, they are often used in a context where both are relevant.
  • To use a humidity sensor correctly you need to adjust the humidity reading based on the temperature so you need to be able to sense the temperature.
Regarding #2 Humidity is measured (most commonly) as Relative Humidity in this context the humidity is relative to both the current temperature and the current pressure of the system being measured (barometric pressure in the atmosphere).

If you need a humidity sensor by itself, I worked up a design that used 2 separate parts to measure humidity and temperature, the temperature sensor part could be removed (or replaced with something of lower accuracy) and it could then be used alone, I'd be happy to get that for you, just send me an email or a PM.

I'll also note that building two separate modules had some costs that were prohibitive. Some of the components (like the IDC socket) are fairly expensive and building a single module is likely to provide for a higher quality, lower cost module.

Edit: Added cost note.

Edited by Chris Walker, 01 October 2012 - 04:37 PM.
split post

Visit the official Wiki! If you can help make it better please do!
When you talk EE use small words, I'm just a Software Developer :)
My Module Store, including the ProtoModule My Blog/Site and Everything Else

If my post helped you please consider pressing the "Like This" button in the bottom right hand corner.

 

Oh my. So many things, so little money!!

 


#13 Nevyn

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Posted 01 October 2012 - 05:48 AM

Something itched about this question. I scratched. Ahhhh...

I think it's the exclusion of another option. The humidity sensor by itself. Are there occasions when just knowing humidity is useful? Or would you always want temperature too? Because I could see that having a choice about what to measure (temp or humidity or both) would be helpful.

In order to get a reliable humidity measurement you normally need to apply a compensation based upon the current temperature. The DHT22 used in the example uses the current temperature when working out the humidity.

Regards,
Mark

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#14 Jack Chidley

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Posted 01 October 2012 - 08:02 AM

I was wondering, as I wrote the note, whether humidity measurement might depend on temperature. Thanks for the clarification Mark.

#15 Nevyn

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Posted 25 June 2013 - 07:58 PM

This module might not be available to buy but a description of how to make the module is now online.

 

The post has a heavy software bias.

 

Regards,

Mark


To be or not to be = 0xFF

 

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#16 Jack Chidley

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Posted 25 June 2013 - 10:21 PM

Another excellent blog post.

#17 Nevyn

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Posted 26 June 2013 - 06:10 AM

Jack,

 

Thanks, I'm glad you like the posts and I hope you find them useful.  I'm going to carry on writing about electronics and software but it will probably be the last regarding the GO! and/or modules for a while.

 

Regards,

Mark


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#18 Jack Chidley

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Posted 26 June 2013 - 09:25 AM

Mark, given your other recent posts, I understand the reasoning.  Like you, I am saddened by the missed opportunity.  The community cannot build Go by itself.  I am, still, waiting for the official firmware.

 

I read the post you referenced on your blog: http://ch00ftech.com...-ive-ever-made/ and I am interested in your estimates of the time required for your work on the modules.

 

Jack



#19 Nevyn

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Posted 26 June 2013 - 12:08 PM

I read the post you referenced on your blog: http://ch00ftech.com...-ive-ever-made/ and I am interested in your estimates of the time required for your work on the modules.

For the two I've put together (OutputExpander and Temperature and Humidity) they took about 30 and 50 hours respectively.  This assumes that you have the base firmware sorted out.  That alone took a while, don't have a number for that as it was part of The Way of the Register series and that was developed over several months whilst I worked out how to develop for the STM8S.

 

I'd also say that to get the modules to a point where they could be sold would take another 10 hours assuming that there were no PCB redesigns required.  The remaining tasks are:

  • Final component selection (best price etc)
  • Final prototype
  • SL approval to use the GO logo
  • Production run

Of all of the above tasks I'd expect the component selection to take the most amount of my time.

 

Hope this helps,

Mark


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#20 Chris Walker

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Posted 27 June 2013 - 07:53 AM

Mark -- this looks like a really nice module!  Thank you for sharing this.

 

Chris






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