PT1000 Temperature sensors

jmspaggi

Hi,

I would like to use a PT1000 temperature sensor with my controller but I'm not really sure how to do that.

PT1000 resistance will vary based on the temperature. I would like to convert the resistance to a frequency so I can ready from the controller. Any clue how I cool do that?

Or maybe it's not a good way and I'm better to read that differently?

I really want to keep this sensor because it can up to +200C.

All the help will be welcome.

Thanks,

JM

Mike Green

You didn't say what kind of controller you're using or what sort of precision you want. For a simple resistance measurement, you could use the RCTIME statement in PBasic. Look at the chapter on the RCTIME statement in the BASIC Stamp Syntax and Reference Manual for details, particularly on the formulas for choosing the capacitor value. If you're using a Propeller, you could get higher precision because of the larger word and higher execution speed.

If you want higher precision and you're willing to use a more complex circuit, you could use an LM331 voltage to frequency converter or a 555 timer in asynchronous mode. With the LM331, you'd have the pulse frequency related to the resistance. With the 555 timer, the pulse width would be related to the resistance. A Stamp would use the COUNT statement for the LM331 or the PULSIN statement for the 555. Again, refer to the Manual for details.

jmspaggi

Hi Mike,

Thanks for your reply. I did not figured that controller can be a variable on this equation.

I'm using a Javelin.

But following your recommation for newbee (RTFM), I was able to find, page 55/56/169, exactly what I was looking for [noparse]:)[/noparse] Thanks to you for providing the RCTIME keyword. That's what I used to find that.

So I will do some testing with rcTime() and see how I can use that with my sensor.

Thanks again,

JM