Analogue to digital convertor ADC

Discussion in 'The Projects Forum' started by siraqieng, May 8, 2009.

  1. siraqieng

    Thread Starter New Member

    May 4, 2009
    8
    0
    Hello


    how can i make 16 bit analogue to digital converter 12 bit or 8 bit .
    even if we can cheat.


    thanks

    sam
     
  2. StarfleetRP

    Member

    Mar 23, 2009
    24
    0
    Do you mean change the 16bit number into an 8 or 12 bit number? If that is the case just do a bit shift to the right.

    unsigned int ADCvalue = 32767; //16 bit

    unsigned char ADC8bit = ADCvalve >> 8;

    this way you keep the 8 most significant bits for an 8 bit number. To make it a 12bit number just shift 4 to the right instead of 8.

    Hope this is what your looking for?
     
  3. mik3

    Senior Member

    Feb 4, 2008
    4,846
    63
    Why do you want to make it?

    You can buy one of the shelf.
     
  4. siraqieng

    Thread Starter New Member

    May 4, 2009
    8
    0
    because i need to change the sampling frequancy by changing the bits for example
    if i have cut off frequancy 3.4 it need to be sampled at 8 khz i need to 8 bit ADC if i need to sample at 12 khz or 16 khz at the same IC what i need to do?

    thanks
     
  5. mik3

    Senior Member

    Feb 4, 2008
    4,846
    63
    Some chips are driven by external clock signals which determine the sampling frequency.

    Which ADC chip are you using?
     
  6. NavjeetSingh

    New Member

    Feb 8, 2009
    9
    0
    I think you need to look for a clock signal such as 555 Timer.
     
  7. siraqieng

    Thread Starter New Member

    May 4, 2009
    8
    0
    Hi mik3
    which chip you prefer me to use? for changing the sampling frequency 2 times
    one for sampling frequency= 8 kHz,
    2nd for sampling frequency= 16 kHz

    which IC you prefer ?
     
  8. mik3

    Senior Member

    Feb 4, 2008
    4,846
    63
    I have never used a ADC chip on its own (I used ADC on PICs). Find one which can be clocked externally and use two 555 to choose between two frequencies.
     
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