Archived Forum

What do you mean by 18%?  Are you saying it is correct at 0 °C but 20 °C reads as 23.6 °C?

Where is your sensor positioned? Is it subject to local heating? There is a small self-heating effect, I have measured it and of course the sensor itself has an accuracy tolerance of ± 0.5 °C. See http://openenergymonitor.org/emon/node/2484

It is correct! The sensor is direct attached to emonTx Temperature Node (on the board) and there is no other heat source around it! I have two emonTx Temperature Node and it's the same for both!

I'm not 100% sure if the sensor is reading the temp with 18% to high temp, but it's not correct anyway... 

I have read the thread you posted, but I'm not sure if any information in this will help me!

Sorry for my bad English, I'm from Sweden =)

Don't worry about your English - it is much better than my Swedish!

Can you record the actual temperature and the temperature that the Temperature Node displays, over as wide a range of temperatures as possible, and post the results?

The Temperature Node sketch does not print the temperature to the serial monitor, so where do you read the data? For testing, you could modify your sketch to print the temperature: after line 110 "float temp = ..." add a new line:

Serial.println(temp);

and that will display the temperature as the sensor reads it. The number that is sent by radio is an integer that is 100 times this to give you 2 decimal digits in the reading.

If this reads the wrong temperature, comment out the old line 111 "digitalWrite(7,LOW);".  This will leave the temperature sensor powered all the time and will show if there is a problem with the sensor not being stable when the command to read the temperature is sent. Remember to put the line back in and remove the "print" when you have finished testing, or your battery will die very quickly.