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Interfacing adc

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Interfacing adc

  1. 1. Interfacing ADC
  2. 2. What is ADC? <ul><li>ADC – analog to digital conversion </li></ul><ul><li>It converts the given analog value to a digital value </li></ul><ul><li>There are lot of digital ICs available to convert analog to digital </li></ul><ul><li>In microcontroller interfacing the frequently used ICs are 0804 and 0808 </li></ul>
  3. 3. 0804 – an ADC
  4. 4. Interfacing ADC
  5. 5. Working of ADC <ul><li>For every interfacing initialization is needed, </li></ul><ul><li>For ADC the initial values are </li></ul><ul><ul><ul><li>INTR=1; // interrupt for completion of ADC process </li></ul></ul></ul><ul><ul><ul><li>rd=1; // read from 0804 </li></ul></ul></ul><ul><ul><ul><li>wr=1; // start conversion write.. </li></ul></ul></ul>
  6. 6. Working of ADC contd. <ul><li>Next step is to start the process of converting analog voltage to digital data </li></ul><ul><li>By changing the state of the write pin – a transition from 0 to 1 will start the conversion. </li></ul><ul><li>End of conversion will be acknowledged by a change in the INTR state… </li></ul><ul><li>See the timing diagram of the conversion starts </li></ul>
  7. 7. Timing diagram of START Conv.
  8. 8. Reading the data <ul><li>To read the data from 0804 the read pin state must be ‘0’. </li></ul><ul><li>After reading the data read pin must be change back into ‘1’ </li></ul><ul><li>The data obtained from the 0804 will be from ‘0’ to ‘255’ , since the ADC is a 8 bit adc and obtained value will be inbetween 2 0 to 2 8 . </li></ul>
  9. 9. Timing diagram of reading from 0804
  10. 10. Assignment <ul><li>Convert analog and display in LCD </li></ul><ul><li>Find the room temperature and display the degree Celsius value in LCD. </li></ul>

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