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MSP430f5510 ADC Vref 3.3V

Jeff Klaassen
Prodigy 90 points

Hallo everybody,

This is a very silly question but i was wondering if the vref+ for ADC can be set to 3.3V or use the Avcc as ref that runs on 3.3V?

I looked in the datasheet and in the ref document (SLAU208) but cant really figure it. The problem is that i have a sensor running on 3.3V (also the MCu runs on 3.3V) but as far as i can tell the ref can not be set higher than 2.5V that would mean i need some extra IC or something to interface them together.

Any tips or feedback would be very helpfull and please bear with me im still a student and (unfortunately) a slow learner.

Thanks in advance,

jeff

  • 0
    Guru 227245 points

    See the users guide, ADC10 chapter.
    Reference for the ADC10 can be either (A)Vcc or the internal reference module (with selectable 1.5V, 2V or 2.5V precision reference)

    The sensor running on 3.3V does not necessarily mean that its output spans to 3.3V too. Well, if it does, and if both have the same 3.3V supply, then you can use AVcc as reference (ADC10SREF_0 in ADC10MCTL0 register) and directly convert the ADC10 reading in sensor output percentage: 100% sensor output gives 1023 conversion result. 0% gives 0 (besides noise)

  • 0 in reply to Jens-Michael Gross
    Prodigy 90 points

    thanks Gross,

    ones again you helped me out. I just wanted to make sure i was doing it right. ADC10SREF_0 did the trick.

    some how i could only find information about the internal ref. And the sensor Vout equals the Vcc so thats why it was important.

     

    Thanks again! 

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