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ds2760 thermocouple kit returns errors with propeller — Parallax Forums

ds2760 thermocouple kit returns errors with propeller

MrBeanMrBean Posts: 8
edited 2010-10-15 08:12 in Accessories
Hi everyone,

I'm not sure If I should be posting this in the sensors section or the propeller section but this seemed to make more sense.

I'm having a strange problem with the DS2760 thermocouple kit. I am using it with the propeller chip and I am using the only object available from the propeller object exchange.
Here is the link to the webpage to download that object.
http://obex.parallax.com/objects/385/

I am recording the temperature to a variable and then displaying that variables data in the parallax serial terminal to see if I am getting a correct temperature reading. It shows the correct temperature for anywhere between 0 and 25 degrees celsius, but when the temperature goes higher than that it gives me an erroneous reading of 65535 no matter how high I go with the temperature. What is really strange is that if I measure the temperature of a frozen item from my freezer so I can get the DS2760 to read to a very low temperature or even all the way down to zero and then reset the propeller chip, all of a sudden I am able to get temperature readings over 100 degrees celsius and it seems that everything is functioning correctly. Then after some time, maybe a few minutes, maybe longer, it stops working again at any temperature above 25 degrees celcius giving me 65535 again. Measuring the temperature down to zero and reseting the propeller chip doesn't even work all the time. Also the temperature used to work until 28 or 29 degrees celsius in the summer when the temperature in the room was hotter. That makes me think of the chip on the DS2760 for the compensation temperature being different, but I don't know what to think

This is very frustrating and I was wondering if there was anyone out there who has successfully got the DS2760 to work with the propeller chip using the object that I gave a link to. I don't know if somehow I got a defective DS2760, but since it does work in some way, I would think it is probably not a hardware issue. This just doesn't make any sense to me. However I am new to microcontrollers in general and the propeller is my first experience with a microcontroller. I did tinker with the object, quoting out some of the code a bit at a time and I found that the compensation temperature was working properly as well as all the calculations for the final temperature, but when I left only the code for just the first temperature reading without any calculations for the final temperature, I found that this temperature reading was the part of the code giving wierd readings and all the other code seemed to be doing it's job properly. So all the code seems to be good except that basic temperature reading. The person who made the object did claim on that page from the link I gave that the object works. Does anyone have any ideas?
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