Nucleo-446re internal adc

[harry123]

Hi everyone

• I want to measure a small voltage of 10mv-50mv of a sine wave.
• Can i use Internal adc of nucleo board ? what is the lowest voltage i can measure using internal adc.

[PGump.1]

Hi,

Is 10mV-50mV peak-to-peak, peak, average, RMS?

What resolution (how many bits) do you need?

Kind regards
Pedro

[harry123]

• Its peak to peak
• 12 or 16 bit

Thank you 

[PGump.1]

Hi,

You'll have to lower your expectations. If you can get the +REF down to 1.7V, you may get 5-6 bits...

I hope that helps.

Kind regards
Pedro

[harry123]

• Is it not possible to measure by keeping vref to 3.3 which is default in nucleo board.
• What will happen if I try to measure, will the adc not give the values or the values it gives is wrong values.

Thank you

[SofLit]

You need to amplify that signal to match the dynamic range of the ADC if you don’t want to change Vref.

Refer to this application note/section 3.2.6:

https://www.st.com/resource/en/application_note/an2834-how-to-optimize-the-adc-accuracy-in-the-stm32-mcus-stmicroelectronics.pdf

[PGump.1 · Accepted solution]

Hi,

You will get scaled down values. Only you can decide if they are any good for your application...

The math behind ADC isn't difficult, start there.

To get the maximum out of an ADC, you need to get a solid understanding of Sampling Theorem...

Kind regards
Pedro