CP/PC364 Data Communications & Networks Laboratory

D/A and A/D Conversion


Digital transmission of analog data, (such as sound and video), requires analog input signals to be converted to digital signals for processing. Once received, the signals then have to be converted to back analog. These conversions are done by analog to digital (A/D) and digital to analog (D/A) converters, respectively. Although you could construct these converters from discrete components, integrated circuits specifically designed for these purposes are usually used.


The objectives for this lab are:

At the beginning of the lab, you should have an Arduino connected to an LCD display and an SPI D/A converter.


image Great care should be taken to avoid static discharge into CMOS based chips.
  1. Combine the sketches for the DAC and ADC circuits so that output from the ADC can be fed to the DAC. Since the ADC is 10 bits, but the DAC is only 8 bits, which bits will you want to send; the most significant or the least significant?
    Drive the ADC input with a sine wave of the appropriate amplitude. Compare the analog output of the DAC with the original sine wave and sketch the signals.
    • How high a frequency can this system accept before the output becomes too distorted?
    • At what frequency do you start to observe aliasing? Does this fit with the conversion time?

    Demonstrate your circuit to the lab supervisor.


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