Infrared Temperature sensor

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1

Totally new here. Thanks in advance for any help.

I am hoping to use a Cobra II, TE35 and an analog non contact temperature sensor for my project.

From what I gather, the infrared ones are affordable. I know they must be, I see them on inexpensive kitchen temperature “guns” all the time.

Seeed has a Grove sensor: http://www.seeedstudio.com/depot/-p-1058.html?cPath=144_147.
Seed also has a Grove Gadgeteer Expansion: http://www.seeedstudio.com/depot/-p-1084.html?cPath=203
It’s an analog sensor and the analog connector on the Cobra says it’s also used for the touch connector on the TE35 so I’m not sure how to even hook that up. Is that possible? Do I need an AD converter to use another port?

Then there are the drivers for the sensor, which are 4.1 and not 4.2 which I was hoping to use. Maybe 4.1 will work on the Cobra II.

I’d feel better if it had a little better accuracy and perhaps a little better range (>9cm), but I’d like to know if there are other options.

Has anyone worked with this Grove sensor?
Has anyone else worked with affordable non contact temperature sensors?

I found other sensors, but they typically ran $185 (USD) or more. That’s not going to work.

Thanks in advance.

Bill

I am recently retired. I developed software and I used to build Dynaco amplifiers when I was a kid. Thought I’d have another run at hardware.

2

If you plan on using the gadgeteer sockets for the infrared senson, then no, you can either have the touch or the sensor hooked up. However, there are plenty (I’ve counted 7) AD pins along the expansion header to wire the sensor up and I would recommend doing just that.

Also, the Cobra II only works with 4.2, there is no firmware available that would allow 4.1 to be run on the Cobra II.

3

James,

Thanks for the quick reply.

I found another sensor that might be better, but I’m not sure how to connect it exactly. I’ll find some info and post a better question.

The GHI Gadgeteer thing has me really excited to build stuff. The Cobra has almost everything I want on a single board, which is awesome. I just need to figure out what else to buy from you guys! :slight_smile:

Bill

4

I’ve worked some of the Grove sensors but not the Infrared temperature sensor. As far as the Grove Gadgeteer Expansion module goes its a rather simple board and I’m sure I have a 4.2 version of it kicking around on my hard drive somewhere. You will still need to code the interface and such. Here are some CodeShare projects that I did using the Grove Expansion Module:

http://www.tinyclr.com/codeshare/entry/516

http://www.tinyclr.com/codeshare/entry/535

I would also be interested in an Infrared Temperature Module if anyone is thinking of building one. I might pickup the Grove one just to try it out.

5

I have designed and built a $10 non contact thermal sensor for Gadgeteer.

I did not bring it to market for the following reasons:
[ol]There is no clear formula for emissivity setting.
It is unfocused, so the spot size is equvilant to the distance. 1 foot from the device the measured area is 1 foot. If you want to measure a small spot then you need to be very close. You can’t use a glass lens, as glass is opaque at these light frequencies.
I wrote the driver for it, but never polished it up, due to point 1 and point 2.[/ol]

It uses the tps006 chip from Texas instruments.
http://www.ti.com/product/tmp006

It requires an X or Y socket.

I can publish the files if anybody want to take it up. Note that the sensor is a pain to solder with hot air, and impossible with a soldering iron. It measures 1.6mm x 1.6mm and has 8 solder balls on the bottom.

6

Wow, thanks for all the responses, guys.

GMod(Errol) - I believe the spot size equal to the distance might be a problem for this application. And I don’t want to struggle with the soldering if I can avoid it.

Duke - That sounds possible. In the meantime, I found another sensor that might actually be better. It seems to have good accuracy and better onboard processing. Here’s a link: http://wiki.bildr.org/index.php/MLX90614. The datasheet even has a link to a video of it in use.

From what this newbie can tell, the interface ought to be compatible with one on the Cobra.

Does that one look better to you? I found it online for $19, quantity one.

7

I have looked at the MLX sensors, and they are nice.

Just be sure to look at it’s field of view, as that same model comes in a wide range of spot sizes.

BTW, the first module you pointed to had an effective sensing distance of 9mm…

EDIT:
This MLX sensor, suffix BAA, also has a 90 degree field of view, so the spot size is again the same as the distance…

8

Right. I checked the MLX90614ESF-BAA, which is 3.3v, single zone and standard field of view. I am trying to build something that’s portable, so I wanted it to have some range, but I haven’t really figured out how much.

Right now I see that there are evaluation boards that work with USB and other ways to experiment with this before I have to get to the I2C communications piece. I see I2C is on the edge of the Cobra II. That keeps me from messing about with even more components.

Already placed an order for the Cobra this morning. Can’t wait to start.

For the sensor, maybe I’ll start with something simpler, like the USB eval version and once I actually have some decent questions, I can ask those.

Again, you guys are awesome for helping.

Reminds me of the CompuServe days when a small bunch of people just wanted to help everyone else and it was a kinder, gentler Internet.