ADC interfacing with Microcontrollers: Programming for ADC0804
►Programming 8051 Microcontroller ►8051 Assembly Programming for ADC0804CODE:
rd equ P1.0 ;Read signal P1.0
wr equ P1.1 ;Write signal P1.1
cs equ P1.2 ;Chip Select P1.2
intr equ P1.3 ;INTR signal P1.3
adc_port equ P2 ;ADC data pins P2
adc_val equ 30H ;ADC read value stored here
org 0H
start: ;Start of Program
acall conv ;Start ADC conversion
acall read ;Read converted value
mov P3,adc_val ;Move the value to Port 3
sjmp start ;Do it again
conv: ;Start of Conversion
clr cs ;Make CS low
clr wr ;Make WR Low
nop
setb wr ;Make WR High
setb cs ;Make CS high
wait:
jb intr,wait ;Wait for INTR signal
ret ;Conversion done
read: ;Read ADC value
clr cs ;Make CS Low
clr rd ;Make RD Low
mov a,adc_port ;Read the converted value
mov adc_val,a ;Store it in local variable
setb rd ;Make RD High
setb cs ;Make CS High
ret ;Reading done
CODE:
#include <REGX51.H>#define adc_port P2 //ADC Port
#define rd P1_0 //Read signal P1.0
#define wr P1_1 //Write signal P1.1
#define cs P1_2 //Chip Select P1.2
#define intr P1_3 //INTR signal P1.3
void conv(); //Start of conversion function
void read(); //Read ADC function
unsigned char adc_val;
void main(){
while(1){ //Forever loop
conv(); //Start conversion
read(); //Read ADC
P3 = adc_val; //Send the read value to P3
}
}
void conv(){
cs = 0; //Make CS low
wr = 0; //Make WR low
wr = 1; //Make WR high
cs = 1; //Make CS high
while(intr); //Wait for INTR to go low
}
void read(){
cs = 0; //Make CS low
rd = 0; //Make RD low
adc_val = adc_port; //Read ADC port
rd = 1; //Make RD high
cs = 1; //Make CS high
}
The next section of the tutorial will cover the programming of 8051 for ADC0804.
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