VTech Alphabert s Magic Readport User Manual download pdf (Page 77)

BM Dept., Govt. Engg. College, Gandhinagar Page 77

EXPERIMENT NO. 17

AIM: Interface 8 bit DAC chip with 89C51 microcontroller. Write a program to generate sine

wave using look up table.

Circuit diagram:

Interfacing details:

• Data lines of DAC-0808 are connected with Port P1 of the microcontroller AT89C51.

• Zener diode is used to provide reference voltage to the DAC.

• Current output of the DAC is converted into voltage by I to V converter circuit formed by

Op-AMP 741.

• Connect C.R.O. at the output of DAC to observe analog signal.

Program:

org 30h

rept: mov dptr,#0400h

mov P1,#00h

start: clr a

movc a,@a+dptr

jz rept

add a,#127

mov P1,a

setb P0.7

acall delay

inc dptr

ajmp start

delay: mov R7,#0ffh

loop: djnz R7,loop

ret

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VTech Alphabert s Magic Readport User Manual Page 77