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EBayo
Beginner
1,449 Views

Read correctly with AREF 2.5V J2. Arduino Kit

Hi!

I have changed the position of the jump 8 (AREF) to be able to read lower voltage (2.5V/1024 = 2.44mV and not 5V/1024 = 4.88mV) but when I do an analogRead, it read all time the maximum 1024. I don't know why. I tried to change to the j9 ioref, but I've not benn successful.

Any recommendation?

Thanks

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6 Replies
idata
Community Manager
74 Views

Hello Eduardo,

 

 

Thank you for your interest in our Intel products.

 

 

You can find in this guide the specifications and steps to set the voltage on the Edison board: https://cdn.instructables.com/ORIG/F2O/8U4Y/I1942TZ5/F2O8U4YI1942TZ5.pdf

 

Let me know if it works out.

 

 

Hope this helps.

 

 

Regards,

 

Octavian
idata
Community Manager
74 Views

Hello Eduardo,

 

 

Are you still encountering any issues?

 

 

Regards,

 

Octavian
EBayo
Beginner
74 Views

Hello Octavian,

I still don't know how to do. I read the documentation you indicated to me but or I don't understand, or it doesn't work.

Why always read 1023? I have connected a simple LM35...

If I put the Jumps J9 and J8 at bottom, it woks well in the range of 0-5V

But at top in range 0- 2.5V not.

idata
Community Manager
74 Views

Hello Eduardo,

 

The LM35 datasheet specifies the sensor operates between 4V and 30V, changing IOREF (J9), this pin will select between 3.3V or 5V logic level. I'd suggest to leave the J9 jumper at the default location. Regarding the AREF (J8) pin, this will select between 3.3V and 5V input.

The LM35 produces voltages from 0 to 1V, ideally the AREF should be selected to 1.1V to get the highest resolution possible. However, this is not possible with Edison. I'd recommend you to revisit the equation used in the sketch.

What is the raw value read from the ADC pin?

Take a look at the following Arduino page:

https://playground.arduino.cc/Main/LM35HigherResolution https://playground.arduino.cc/Main/LM35HigherResolution

 

Hope this helps.

 

 

Regards,

 

Octavian
idata
Community Manager
74 Views

Hello Eduardo,

 

 

Are you still facing this issue?

 

 

Regards,

 

Octavian
EBayo
Beginner
74 Views

No! Thank you so much

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