# Interfacing of Digital to Analog Converter

Updated on 2017/08/10 10:38

## Syllabus

• Interfacing of 8051 Microcontroller with DAC (Digital to Analog Converter)

## Introduction to DAC

$I_{out}=I_{ref}\left [ \frac{D7}{2}+\frac{D6}{4}+\frac{D5}{8}+\frac{D4}{16}+\frac{D3}{32}+\frac{D2}{64}+\frac{D1}{128}+\frac{D0}{256} \right ]$

where, Iref=Reference current=2mA
D7 = MSB bit
D0=LSB bit

How to convert Iout to voltage in DAC0808?
DAC gives output in the form of cureent, so outside of the DAC current(I) to voltage(V) converter is connected, which is then provided to oscilloscope.

## Interfacing

### Interfacing Diagram

1DAC interfacing with 8051 microcontroller

### Assembly Language Programs

Program: Write an ALP to generate Square wave form on port P1 of 8051 microcontroller using DAC.

Flowchart for Square Wave generation using DAC

Square Wave Generation using DAC
ORG 0000h
mov P1,#00H
repeat:Acall squarwave
sjmp repeat
squarwave:mov P1,#FFH
Acall delay
mov P1,#00H
Acall delay
ret
delay:mov r0,#20
up2:mov r1,#250
up1:mov r2,#250
Here:djnz r2,Here
djnz r1,up1
djnz r0,up2
ret
END

Program: Write an ALP to generate Triangular wave form on port P1 of 8051 microcontroller using DAC.

Flowchart for Tringular Wave Generation using DAC

ORG 0000h
mov P1,#00H
repeat:Acall triwave; generate triangular wave
sjmp repeat
triwave:mov A,#00H
INCR:mov P1,A
INC A
CJNE A,#0FFH,INCR
DECR:mov P1,A
DEC A
CJNE A,#00H,DECR
ret
END

Program: Write an ALP to generate Stair-case wave form (with 5-steps) on port P1 of 8051 microcontroller using DAC.
Solution:- As we need 5-Step staircase waveform.Hence Accumulator can have maximum value of 255 hence to get 5 steps initial value to be added is 51H

ORG 0000h
mov P1,#00H
repeat:Acall stair_case_wave; generate staircase wave
sjmp repeat
stair_case_wave:mov A,#00H
mov P1,A
Acall delay
mov P1,A
Acall delay
CJNE A,#0FFH,Back
SJMP stair_case_wave
delay:mov r0,#20
up2:mov r1,#250
up1: mov r2,#250
here:djnz r2,here
djnz r1,up1
djnz r0,up2
ret
END

## References

• Interfacing diagram by Jayesh Gopal, WikiNote Volunteer, SKNCOE,Pune
• Created and developed by Prof. S.M.Wagh, SKNCOE, Pune
• WikiNote Foundation
1. ^ Image by Jayesh Gopal, SKNCOE, Pune
Tags:
Created by Sujit Wagh on 2017/08/03 16:36

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