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Interfacing ADC and DAC with 8085 using 8255

Interfacing ADC and DAC with 8085 using 8255. Interfacing adc with 8085 using 8255. Interfacing ADC with 8085 using 8255. Interface 8255 with 8085 that are explained before. The ADC 0808 is 8-channel 8-bit ADC chip. It has 8 analog inputs i.e. IN0-IN7.

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Interfacing ADC and DAC with 8085 using 8255

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  1. Interfacing ADC and DAC with 8085 using 8255

  2. Interfacing adc with 8085 using 8255

  3. Interfacing ADC with 8085 using 8255 • Interface 8255 with 8085 that are explained before. • The ADC 0808 is 8-channel 8-bit ADC chip. • It has 8 analog inputs i.e. IN0-IN7. • One of these channels is selected by sending address to a address line of ADC. The logic level and selected channel is as shown:

  4. The analog signal is connected to channel 3. The digital equivalent data D0-D7 is connected to PA0-PA7 of Port A. The PC0, PC1 and PC2 lines of Port C are connected to channel select address lines of 8255. PC3 is connected to SOC (Start of conversion) and ALE signal (Input signal). EOC (End of conversion) which is an output signal of 8255 connected to PC7 of Port C.

  5. Interfacing ADC with 8085 using 8255 • The PB0 of Port B is connected to OE (Output Enable) input signal of ADC. • The control word format for above interface Is given as: • Control word= 98H

  6. Interfacing ADC with 8085 using 8255 • Data from channel selection: A high to low signal is applied for obtaining data from ADC. • Step – 1 • Data to Port C Address=0BH (SOC= HIGH)

  7. Interfacing ADC with 8085 using 8255 • Step – 2 • Data to Port C Address=03H (SOC= LOW)

  8. Interfacing ADC with 8085 using 8255 • Step – 3 Output Enable(OE) • Data to Port B Address=01H (OE= HIGH)

  9. PROGRAM CODE

  10. Interfacing DAc with 8085 using 8255

  11. Follow the initial 3 steps of interfacing of 8255 with 8085 that are explained before. • The DAC 0808 is 8-bit digital to analog convertor IC. • It converts digital data into equivalent analog current. • Therefore I to V converter is used to convert analog output current of DAC to equivalent analog voltage. • PA0-PA7 pins of Port A are connected to D0-D7 pins of DAC. • In above DAC dual power supply of +/- 10V is applied with reference voltage 10V as shown in diagram. • According to theory of DAC Equivalent analog output is given as:V0=Vref

  12. Ex:1. If data =00H [00000000], Vref= 10VV0= 0 Volts.2. If data is 80H [10000000], Vref= 10V V0= 5 Volts.

  13. The control word format of 8255 for above interfacing is given as: • Control word = 80H

  14. Program: PROGRAM CODE

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