Help: LM35 & ADC0831 interfacing with 8051

bigdogguru said:

Typically, at least in your case, the microcontroller, AT89S52, is the master and the peripheral device, ADC0831, is the slave.

As both MICROWIRE and SPI allow for more than one peripheral device to be connected to the data input and output line at one time, the Slave Select (SS) or Chip Select (CS) line is simply a GPIO line which selects the particular peripheral device with which to communicate.

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Introduction to Serial Peripheral Interface


BigDog

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bigdogguru said:

The ADC0831 has a resolution of 8-bits, range of 0 to 255, therefore you can simply store the conversion in an unsigned char or an array of unsigned char if you wish to store more than one conversion and calculate the average of the set.

I would first recommend supplying the ADC with a stable voltage of known value and then develop your SPI/MICROWIRE read/write/control routines, using the LCD to display the resulting 8-bit value.

Once you'll succeed in transferring and storing the conversion value from the ADC0831 to the AT89S52, you can then connect the LM35 and work on the conversion routines.


BigDog

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#include<reg51.h>

void delay (int);
void lcd_init (void);
void lcd_cmd (char);
void lcd_data (char);
//char read_data (char);

sbit RS = P1^0;
sbit EN = P1^1;
sbit CS = P1^2;
sbit CK = P1^3;
sbit DO = P1^4;
char value;

void delay ( int a )
{
	int i,j;
	for ( i = 0; i < a; i++ )
		for ( j = 0; j < 1275; j++ );
}

void lcd_init ()
{
	lcd_cmd(0x38);		  
	delay(5);
	lcd_cmd(0x0F);      
	delay(5);
	lcd_cmd(0x0C);
	delay(5);
	lcd_cmd(0x80);
	delay(5);
}

void lcd_data ( char y )
{
	RS = 1;
	P2 = y;
	EN = 1;
	delay(5);
	EN = 0;
	delay(5);
}

void lcd_cmd ( char z )
{
	RS = 0;
	P2 = z;
	EN = 1;
	delay(5);
	EN = 0;
	delay(5);
}

unsigned char read_data()
{
	unsigned char i;
	char result;
	
		CS = 1;
		delay(5);
		CS = 0; 
	
		CK = 1;
		delay(5);
		CK = 0;
		delay(5);
		CK = 1;
		delay(5);
		CK = 0;
		delay(5);
	
		for ( i = 0; i < 8; i++ )
		{
			CK = 1;
			delay(5);
			CK = 0;
			delay(5);
			result = result << 1;
			result = result | DO;
			delay(5);
		}
	return result;
}

void main ()
{
	lcd_init();

	while(1)
	{
		value = read_data;
		lcd_data (value);
	}
}