Discussion in "Project Help" started by    Pater    May 14, 2018.
Mon May 14 2018, 05:36 PM
#1
Basically my project is based on Data Acquisition system, so I want to acquire the data from various sensors in the PC.

For this i have used ADC0808 for converting Analog data to Digital data (8 bits), and these digital bits are given to any one port of micro-controller (89S52). The micro-controller then receives the bits and transmit it serially so that PC can receive the serial bits.

I have used "ADC0808 module with external clock" (By Silicon Technologies) :- attachment-1 &
"89S52 development board" (By Silicon Technologies) :- attachment-2

My code is as follows,
---------------------------------------------------------------------------------------------------------------------------
#include<reg51.h>

void delay_sec(unsigned int);
void delay_us(unsigned int);

void decimal();
void serial(char c);
unsigned char d1,d2,d3,d4;
void InitADC(void);
unsigned char ReadADC(unsigned char);

#define AN0 0
#define AN1 1
#define AN2 2
#define AN3 3

sbit Add_A = P2^0;
sbit Add_B = P2^1;
sbit Add_C = P2^2;
sbit ALE = P2^3;
sbit EOC = P2^4;
sbit OE = P2^5;
sbit START = P2^6;



#define Data_Bus P0
#define HalfCycleDelay 10 // usecs


void main()
{

unsigned char I;
InitADC();

while(1)
{
I= ReadADC(AN0);
}

}

void InitADC(void)
{
Add_A = 0;
Add_B = 0;
Add_C = 0;
ALE = 0;
EOC = 1;
OE = 0;
START = 0;

Data_Bus = 0xFF;
}

unsigned char ReadADC(unsigned char Channel)
{
unsigned int i = 0;
unsigned int ADC_value = 0;

/*Selecting analog Channel by providing respective
bits to A,B,C addresses*/
switch(Channel)
{
case AN0: Add_C = 0; Add_B = 0; Add_A = 0; break;

}

delay_us(HalfCycleDelay); // 250kHz Frequency
ALE = 1; // Enable Address Latch

delay_us(HalfCycleDelay); // 250kHz Frequency

START = 1; // Start ADC Conversion
delay_us(HalfCycleDelay); // 250kHz Frequency

ALE = 0; // Disable Address Latch
delay_us(HalfCycleDelay); // 250kHz Frequency

START = 0; // Complete the start pulse

for(i=0;i<2000;i++)
{

delay_us(HalfCycleDelay); // 250kHz Frequency
if(!EOC) // Wait for EOC to be low
break;
}

for(i=0;i<2000;i++)
{

delay_us(HalfCycleDelay); // 250kHz Frequency
if(EOC) // Wait for EOC to be High
break;
}


OE = 1; // Enable Output
delay_us(HalfCycleDelay); // 250kHz Frequency

delay_us(HalfCycleDelay); // 250kHz Frequency

delay_us(HalfCycleDelay); // 250kHz Frequency


ADC_value = Data_Bus; // Read value

decimal();
serial(d1+0x30);
serial(d4+0x30);
serial(d3+0x30);

delay_sec(1);

delay_us(HalfCycleDelay); // 250kHz Frequency
OE = 0; // Disable Output

delay_us(HalfCycleDelay); // 250kHz Frequency
return ADC_value; // Return ADC value
}


void decimal()
{

d1 = Data_Bus /100;
d2 = Data_Bus %100;
d3 = d2 %10;
d4 = d2/10;

}


void serial(char c)
{

TMOD = 0X20;
TH1 = 0XFD;
SCON = 0X50;
TR1 = 1;
SBUF = c;
while(TI==0);
TI = 0;

}

// Function for approximate delay in Secs.
void delay_sec(unsigned int d)
{
unsigned int i;
for(i=0;i<(d*20);i++)
delay_us(50000);
}

// Function for approximate delay in given uSecs.
void delay_us(unsigned int d)
{
unsigned int i, limit;
limit = d/15;
for(i=0;i<limit;i++);
}

----------------------------------------------------------------------------------------------------------------

So the main problem is that I am not getting Analog to Digital conversion on the port of micro-controller and also no data in the PC (Used hyper-terminal for getting serial data) & if getting, am getting any random data in the PC.

I have made all connections as per the code but it is not working.

So please help in this regard and give suitable solution regarding Hardware part or the Programming part.

Mon May 14 2018, 10:17 PM
#2


So the main problem is that I am not getting Analog to Digital conversion on the port of micro-controller and also no data in the PC (Used hyper-terminal for getting serial data) & if getting, am getting any random data in the PC.

Pater



You code works okay on Proteus.
Random values looks like wiring or power problems.

Where do you get your test input voltage ?

What happens if you connect ADC0809 IN0 directly to ground ?
What happens if you connect ADC0809 IN0 directly to +5volts ?


[ Edited Mon May 14 2018, 10:19 PM ]

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