Temperature shown on Dashboard for TMP35 is incorrect


#1

Using an Arduino Uno with W5100 ethernet shield and iOS 10.12.2. This is a simple test case of Cayenne IoT using a TMP35 to send a temperature profile to the Cayenne Dashboard. The sensor is connected to A0 on the Uno and Virtual Pin 1 is specified on the sketch. The temperature shown on the Dashboard is in the low 400-deg F. Any obvious thing I’m overlooking? Thanks.


#2

Hi @rkfujita,

Can you confirm that the widget is set to read Virtual Pin 1? It sounds like it may be reading the raw data from the A0 pin instead.

If that’s not it, let me know which of the 3 temperature writing functions you’re using in the sketch (whichever is uncommented).


#3

HI siegel,

Thanks for your response to my inquiry. Today I removed the ethernet shield from my Uno and ran a simple sketch to check my TMP36 sensor. I got the correct temperature w/o the shield, so I went online and found a site that indicated that some ethernet shields cannot use A0 or A1 to send analog data from a sensor. After reinstalling my shield on the Uno and using A3, I was able to get a much lower temperature sent to the TMP36 sensor on the Dashboard. Now it looks like I’ll be able to make a correction to the A3 reading and get the correct temperature showing on the Dashboard. Ever run into this situation before?

Thanks again for you assistance. Looking forward to using your Cayenne system for other projects.

Best regards,
Robert Fujita


#4

I am aware of some restrictions on pins 1 and 0 on some models (though I thought it was the digital pins in this case?) The test I set up to check your issue was on Uno/W5100 and is using A0 and still hooked up. So I’m not convinced it was the reserved pins in this case.

Either way, I’m happy that your readings are looking correct now after rebuilding the project with A3!