Interfacing Honeywell TD4A Temperature Sensor

CPUMAN

I'm trying to read the sensor with the stamp with some reasonable accuracy.· I intialy tried using a RC circuit to read the sensor but as I'm sure many of you already know the values would vary wildly from what the real tempature was.

So my question is simple what is·a reasonably reliable·way of interfacing it to the stamp?

I've attached the data sheet for the sensor.

Any help provided is much appriciated!



Thanks,

Chris

Post Edited (CPUMAN) : 8/21/2006 6:08:34 AM GMT

Chris Savage

Chris,

·· Depending on your RC circuit you may have drawn too much current through the sensor, which would cause heating and affect your readings.· I would recommend a voltage divider circuit typically used with one of these sensors and design it to keep the current draw at or below the reocmmended 1000 uA.· Depending on the resolution you need, you could use an ADC0831 to read the divider.· If you need more resolution, use a 12-bit ADC.· I hope this helps. Take care.


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Chris Savage
Parallax Tech Support
csavage@parallax.com

CPUMAN

Actualy it was the RC circuit itself that was causing the wild readings. If the capacitor's tempature changed slightly the values would change wildly.

I remember reading something that suggested using an ADC, I just wasn't sure if a voltage divider was the correct way to hook the sensor into the ADC.·I'll have to give it a shot.

Thanks.

Chris Savage

Hello,

·· Yes, capacitor temperature could certainly affect the reading, but as I said, it could also have been current through the element.· There are a lot of considerations when trying to get accurate temperature measurement.· Voltage dividers are often used with thermistor circuits, so it could work well here.· Good luck with it.

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Chris Savage
Parallax Tech Support
csavage@parallax.com