Looking for advice: Temp and Humidity

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Hi guys.

I need to monitor several temp and humidty sensors using an Arduino Mega. Therefore I would like to keep the pin usage down as much as I can. What would everyone suggest? I have done a bit of a search through this forum and noted a few exaples but since I can start from scratch, which is the easiest etc to implement?

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I should also have said that the sensors are located up to 10 metres away from the arduino and connected by cable

[LeighM]

In that case, what are they? and what is their interface?

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In that case, what are they? and what is their interface?

Thats my question. If I want to locate them on board I can use i2c etc but a quick google of that protocol suggests that i2c isnt really meant for connection over cable. So if you wanted to locate humidity and temp sensors at the other end of 10 metre cables, what would your preference be?

[LeighM]

OK, when I read "sensors are located" I thought you were wanting to connect to an existing network of sensors.
As you say, if you are building from scratch and want to use component level devices, then connecting directly at 10 meter cable length is going to give you problems.
You need to consider if you want to use off the shelf sensor modules, with say current loop interface, or if you are wanting to do more DIY development?
From the limited information, looks like you need to consider building a small processor board at each sensor point, having MCU, Temp/Humdity sensor and then say RS485 or RS232 interface to return data to your central point (or CAN to a MIAC).

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I think I will end up doing current loops for now although I didnt really think of putting processors at each location. I may even consider that option and simply use basic processors..

Many thanks guys.....

Peter

EDIT: I may even be able to ry my zigbee radio usints. Bought them for a project and never ended up using them so sitting around doing nothing.

[petesmart]

Hi Peter,

I would give your signee units a go... They have both analogue and digital inputs that can interface with your sensors...if you have the advance versions containing a co processor you can run Python scripts to gather and process data...

For now to get started, all you need to do is send bytes of raw sensor data back to your project for process and display....

Best

Pete

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Actualy Pete I didnt think of that. I was going to put Arduinos remotely as well but I see what you mean. Sometimes that idea is that simple one over thinks things and misses it all together

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Further to my last I have had a bit of time to do some reading. It looks like I can use my sensors hooked to my Xbbes out in the field without have auduinos or any other stuff hooked to them.

I can see using flowcode I can use the SendATCOMMAND to send the data request to the remote zigs etc like 7E 00 05 81 00 00 00 00 7E and I get some data back. In my reading it says that it can return up to say 100 bytes of data. So do I use

GetATresponse (byte)

ReadATresponse (indx)


and if so, do these come back as a string ?

Thanks heaps, Peter

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I did another search on the forum using a different set of words and found this topic

http://www.matrixtsl.com/mmforums/viewt ... bee#p62371

Which is basically what I need to do. I am needing to read and control the IO's on the zigs and also read the analog values so would it be better to use the rs232 component instead of the Zigbee one?