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Thermometer (3-pin e-block) powered with 3.3 volts. Possible?


#1

Hello,

I’m a newbie. I have a fez domino + fez connect shield + 3-pin thermometer
http://www.ghielectronics.com/catalog/product/156

The thermometer is connected to An2 on the fez connect shield. The thermometer works fine with power 5 volt. But if I move the jumper to power the connectors An2 and An3 with 3.3 volt, the termometer gives me wrong temperature.

An example: with 5 volts gives me 22 Celsius (ok). With 3.3 voltes give me 9 Celsius (wrong). Is there a way to adjust it? In the driver I found:
adc = new AnalogIn((AnalogIn.Pin)pin);
adc.SetLinearScale(-22, 56);
Can I adjust it changing the two values? What are the right values for 3,3 volt?

Thank you very much

Fabrizio


#2

Which jumper are you referring too?


#3

Yes if you use 3.3V then you have to change the drivers. We do not have the values, this i for you to experiment with :slight_smile:


#4

@ Gus: any suggestion on how to get the right values? What steps can I do to get them? thank you


#5

The easiest way is to scale it down (5/3.3)*value? I just woke up and can’t think math just yet :slight_smile: