Humidity Sensor Options?

[CallRET]

I am very new to these controllers, and all such controllers.  Enjoying the heck out of all my options and making things do stuff.  Great fun!
 
I have the PLC board; I have searched, and I did look in the sensors thread, but I thought I would ask here.  What are my options for humidity sensors? 
 
I understand the WC was made for the H4000 series, and even has a special port for it.  But that allows just one.  And I would like a few.  Or several.
 
Are there any Humidity sensors with linear 0-5V outputs?
Can we hack the Humidity port and logic to support something like the DHT or some other one wire chainable sensor?  Something like these awesome temp sensors would be perfect.
Are there other options I have not thought of?
 
Thank you for yout time.
 
P.S.
I think CAI is pretty awesome.  Reading how they have supported users in this forum and added features suggested here is pretty refreshing.  The online bootloader loading thread was pretty neat, where CAI totally changed it mind and allowed online firmware updates, with the help of users here.  Very happy to support such a company.

 

[CAI_Support]

Current Honeywell sensor is analog sensor, DHT is digital sensor similar to 1-wire, they are not work together.  We had asked users here about their opinion, they prefer the precise Honeywell sensor over lower resolution DHT sensor.  We may produce a separate firmware allowing DHT sensor support instead of DS18B20 and Honeywell sensor.  But it will be difficult to maintain multiple versions of firmware.

 

[CallRET]

Sorry for not getting back sooner.  The forum view said no replies, and I didn't get an email.  I actually clicked on this by accident and saw your reply, and was surprised!
 
Don't get me wrong, the H4000 is a very nice chip.  As you know, its biggest downside is the lack of bus options.  The other is the cost.  Another is the work the IC has to do to get RH calculations.
 
But there are critiques to the H4000.  Not having temp measured where the humidity sensor is leads to less accuracy for many humidity related applications.  And the H4000 is not really much more accurate than the DHT22 and newer sensors.
 
I really love the one wire bus the temp sensors are on.  It would be very useful to me to have the EXACT same thing with the option of plugging a humidity AND temp sensor in place of a onewire temp sensor.
 
I guess that would mean adding H1...H8 to I/O identifiers, and probably other things i have not thought of.  But I guess you could dump the h4000 code. 
 
Have you talked to aosong about options?  What is the easiest path to multiple Humidity sensors with the WebControl?
 
As a side note, what is the plan for humidity sensing options with WC32?

 

[CAI_Support]

Thanks for your posting.  Since we support firmware update through bootloader, it might be best to have different firmwares, some support DHT22 and some support DS18B20 and H-4000. 
 
DS18B20 and H-4000 are calibrated sensors, which means the factory already calibrated in certain condition to rated degree. I don't think DHT22 is calibrated, so it might have bigger range when reading the same thing.
 
WC32 allows firmware update, too. So that with different firmware would also help. However, WC32 comes with a dedicated 1-wire bus controller, so that it has the best 1-wire bus support, including the parasite devices.  That dedicate controller cost is part of contribution to higher price for WC32, along with dedicate NIC controller for higher speed communication.  Because of that, we will probably not remove 1-wire support on any WC32 firmware in any firmware.

 

[az1324]

DHT22 is not addressable so they each need their own I/O pin. 

 

[CallRET]

Data Sheet for DHT22 
  www adafruit com/datasheets/DHT22.pdf
 
I know i am not supposed to post links, but this is not spam, this is to inform CAI_Support
 
That doc says that they are calibrated and that they support the one wire bus?
 
Edited to add correct sheet

 

[CallRET]

DHT22 is not addressable so they each need their own I/O pin. 

can we put them in a package to make them addressable?

 

[az1324]

"one wire bus" is used there as a generic term that means you don't need separate wires for transmit and receive.  It is not related.
 
Sure you can do many different things to make them addressable and/or 1-wire compatible if you design the additional circuitry and code to make it happen.

 

[CAI_Support]

Thanks for the datasheet link, it did not have programming spec in it. From what we know Maxim did not license its 1-wire bus device to anyone, so that it is probably a similar to 1-wire logic.  We need to have programming spec to see exactly.

 

[CallRET]

"one wire bus" is used there as a generic term that means you don't need separate wires for transmit and receive.  It is not related.
 
Sure you can do many different things to make them addressable and/or 1-wire compatible if you design the additional circuitry and code to make it happen.

So what would you recommend to add multiple humidity sensors to the WC?

 

[CallRET]

Thanks for the datasheet link, it did not have programming spec in it. From what we know Maxim did not license its 1-wire bus device to anyone, so that it is probably a similar to 1-wire logic.  We need to have programming spec to see exactly.

It has been stated in many places that it is not one wire addressable, as az1324 stated.  I was confused and in error on this.
 
have you looked at the SHT1x sensors?  http://www.sensirion.com/fileadmin/user_upload/customers/sensirion/Dokumente/Humidity/Sensirion_Humidity_SHT1x_Datasheet_V5.pdf

 

[az1324]

So what would you recommend to add multiple humidity sensors to the WC?

Convince them to add support for the common 1-wire humidity sensor design that uses a DS2438.  Otherwise, it's going to be more trouble than its worth and easier to use a different board.

 

[CallRET]

Convince them to add support

Who is the 'them' you are referring to?  The sensor makers?
 
DS2438 is a Smart Battery Monitor.  How does that help with a Temp Humidity sensor?

Couldn't CAI just switch to some other protocol instead of the closed proprietary 1-wire one?

 

[az1324]

Google DS2438 humidity sensor and you will see that it is a common design and available to buy from a few vendors.  If you convince CAI to add support for it then it would be the easiest way.  If you have some suggestion for an alternative you can certainly propose it.

 

[CallRET]

az1234;
 
If the "DS2438 humidity sensor" is a commodity item, and CAI already does one wire support in firmware, then perhaps that is the path of least resistance.
 
Google could not find a vendor for such a device.  Do you have a link?  I found all the people hooking the humidity sensors to the chips, so perhaps one does not need a vendor, but this project might have more support if we can show CAI that the items exist from actual vendors?
 
Are you thinking they might add this to the Temp sensor code?  Or add it in place of the H4000 support code and place it on the Humidity pins?  Or perhaps we should ask CAI_Support on what they think is workable?