Teensyduino analogReference (INTERNAL) same as default?

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astroyam

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Hi,

It seems from some posts that to get stabler analogRead voltages, it is best to use analogReference(INTERNAL) for Teensy 3.0 using TeensyDuino. Using a voltmeter, the ARef seems to be 3.3V. Is this a different regulator than using no call to analogReference? Is it in fact 3.3V or something else, and is it more stable than using the default? (I'm assuming the default is 3.3V as in the 3.3V pin, not 5 V off the USB entry point?)
Basically, I'm confused on what the difference between INTERNAL and no call is...

Thanks for any feedback...
 
Yes, the default is the 3.3 volt power.

INTERNAL will use the 2.56 volt reference on Teensy 2.0, or the 1.2 volt reference on Teensy 3.0.
 
Hi, I read above that the Teensy++2 aref(INTERNAL) uses the 2.56 volt ref. Is this the default ? Or does it default to VCC (5 volts) ? I read elsewhere that the 5 volt input is the default. It seems to act like it is using the 2.56 volt ref that leads to a full scale reading at 2.56 volts input.

THanks,
Brian
 
Im curious, my signal coming in is biased at 2.5V and Id like my reference to be to 5V.

The system is powered by 5V overall. What call do I make on analogReference() to make this happen?

Thank you!
 
On Teensy 3.0 & 3.1, there is no way to get a 5V analog input range. 3.3V is the maximum possible range.

For a larger range, you'll need to use resistors or some other attenuator circuit to reduce the signal to the ADC input range.
 
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