what's the input voltage of ADC of PIC16F877A ?

Discussion in 'Programmer's Corner' started by alarassi, Feb 6, 2010.

  1. alarassi

    Thread Starter Member

    Feb 6, 2010
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    hello everybody

    i have simple Question here but since im new dealing with PICs i need an answer for my question!!

    i'll be using pic16F877A to display a waveform of heart sound of graphic LCD!

    i just wanted to know the range of maximum and minimum input voltages to the ADC of the PIC16F877A ! in other word how much the voltage range of the amplified signal must be in order to be received by the ADC ??


    thank you :)
     
  2. spinnaker

    AAC Fanatic!

    Oct 29, 2009
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    Did you read the datasheet? It is in there. Probably0-5VDC or maybe 0-3.3 .

    But is will be in the datasheet.
     
  3. t06afre

    AAC Fanatic!

    May 11, 2009
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  4. alarassi

    Thread Starter Member

    Feb 6, 2010
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    i did read the data sheet but since im new to it i couldn't understand! bcz it mentions something about Vref and i don't undrestand what's meant by Vref!!?

    how if i have a bipolar signal, how can pic read it !!?

    thank you
     
  5. alarassi

    Thread Starter Member

    Feb 6, 2010
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  6. BMorse

    Senior Member

    Sep 26, 2009
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    Vref is the voltage reference for the pic's ADC, you can set this as an internal referrence or use an external reference tied to the Vref pin (RA3).... these settings can be found in the datasheet as well...


    The maximum voltage the Pic ADC can accept is 5 volts.

    My .02
     
  7. spinnaker

    AAC Fanatic!

    Oct 29, 2009
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    You need to convert the signal from + - to 0 - 5VDC. 2.5 Volts would be your "zero". There are a number of oscope pic projects on the internet.

    But this is a very big project for a newb. I should know. I am one. :)

    You really should start with something like a DMM.
     
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