Teensy 3.2's ADC Internal Reference Voltage and its Analog Resolution

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hacmachdien

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Hi guys,

I'm working on a project that measure a voltage signal at 0.3 VDC offset and 0.0015 VAC oscillation. I'm planning to buy a Teensy 3.2 because I could see that it has a 1.2V ADC Internal Reference Voltage, at 12-bit digital resolution the voltage resolution would be 1.2V/2^12 = 0.00029V which is enough for my application. Am I correct in my estimation?

PS: Does Teensy have a technical datasheet that describe control registers of the ARM core? I cannot find it anywhere.
 
Actually achieving noise low enough to really get all 12 bits is not as easy is it might seem. In particular, your signal must have a low source impedance.
 
I agree with Paul, to get 12 real bits you should probably convert at 16 bits, hardware average and a low impedance. It can be done, but it also depends on the speed that you want to get the measurements.
 
If your goal is to have all of it done in the teensy that's cool. Personally for such a small signal I would consider adding an op amp with some gain. It could help with having low impedance to the adc and you might get a better signal to noise ratio.
 
With the PGA the "on paper" resolution is even better than that, I've successfully used the teensy's internal adc and PGA to measure signals smaller than what the op is describing, (I was directly reading a load cell with the teensy) but I had time to do a lot of averaging.
 
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