VTech Alphabert s Magic Readport User Manual download pdf (Page 72)

Lab Manual of Microcontroller & Interfacing Page 72

EXPERIMENT NO. 16

AIM: Interface ADC0808 with AT89C51 microcontroller. Write a program to read analog

voltage applied at the input of ADC. Display hex code of analog value on LEDs connected

at port P0.

Circuit diagram:

Program:

; Microcontroller connections to ADC0808/9 lines.

START EQU P3.6 ; Pin 6 Start

EOC EQU P3.2 ; Pin 7 EOC

OE EQU P3.7 ; Pin 9 Output Enable

ALE EQU P3.6 ; Pin 22 ALE

ORG 00h

MOV P0,#00h ; P0 OUTPUT PORT TO DRIVE LEDs

MOV P1,#0FFH ; P1 INPUT PORT TO READ ADC

MOV P2,#00H ; P2 OUTPUT PORT TO SELECT CHANNEL

MOV R0,#05H

LOOP: MOV P0,#0FFH

ACALL DELAY

MOV P0,#00H

ACALL DELAY

DJNZ R0,LOOP

BACK:

MOV P2,#00H ; SELECT ADC CHANNEL 0

ACALL SDELAY

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VTech Alphabert s Magic Readport User Manual Page 72