Temperature sensor from Analogue to Digital

Thank you for the overview, I appreciate it. Now I am having a problem on how to convert the incoming 8-bit data from ADC to a temperature reading by using the keil Software. Futhermore, I am using AT89C52 micro-controller.

I am aware that 8-bit data would have 256 combination from 0000 0000 to 1111 1111. Each step from 0000 0000 to 0000 0001 contribute to a certain degree C. However, how can i programme to allow the incoming binary to becoming a temperature reading appearing on the keil?

Thank you for the overview, I appreciate it. Now I am having a problem on how to convert the incoming 8-bit data from ADC to a temperature reading by using the keil Software. Futhermore, I am using AT89C52 micro-controller.

I am aware that 8-bit data would have 256 combination from 0000 0000 to 1111 1111. Each step from 0000 0000 to 0000 0001 contribute to a certain degree C. However, how can i programme to allow the incoming binary to becoming a temperature reading appearing on the keil?

how can i programme to allow the incoming binary to becoming a temperature reading appearing on the keil?

How about using an array? For example:

float temp_table [256] =
{ ... };

"Each step from 0000 0000 to 0000 0001 contribute to a certain degree C."

Exactly - so all you need to do is apply the scale factor that relates the 1-bit step to a certain degree C.

You may also need to add an offset to account for the Celsius temperature corresonding to the 8-bit binay 0000 0000.

Assuming it's linear, it's your good old y = mx + c

Note that this has nothing specifically to do with Keil - the principle is the same whatever tools you use, and whatever language, from whatever vendor!

Try thinking about how you'd do it by hand!

Perhaps you are confused by the fact that there are actually two scale factors involved here:

1. As Drew pointed out, the sensor produces a linear +10 mV per degree C.
So that's an easy one - you can easily get from mV to degrees C, can't you?

2. There's the scale factor of the ADC:
* what voltage (and, thus, temperature) does the value 0x00 represent?
* what voltage (and, thus, temperature) does the value 0xFF represent?

From there you can easily deduce what voltage step (and, thus, temperature step) produces a 1-bit step in the ADC value (eg, 0x00 to 0x01)

"Futhermore, I am using AT89C52 micro-controller."

Again, that's irrelevant - the principle is the same irrespective of what you run it on!

thanks! by the way, which port would i acquire the 8bit data because the AT89C52 have 4 port?

Futhermore, i have set aside P0 to LCD display and P1 to keypad.

"which port would i acquire the 8bit data because the AT89C52 have 4 port?"

You choose!

Below is the C prog. I notice that the problem is lies with "OPORT = instr;"
because it suppose to move what is in instr into OPORT which is in Xdata at location 0000h but it did not.

#include <reg51.h>

void delay5ms(void);
void delay1ms(void);

void lcdWriteInstrReg(char instr);
void lcdInit(void);
void lcdClrScr(void);

char xdata OPORT _at_ 0x0000;

sbit pinRW = P3^3;
sbit pinRS = P3^4;
sbit pinE = P3^5;

void main(void)
{

lcdInit();
while(1);
}//end main

void lcdWriteInstrReg(char instr)
{

OPORT = instr; //o/p to D0-D7
pinRW = 0; //write
pinRS = 0; //RS=0 for instr Reg
pinE = 0;
pinE = 1;
pinE = 0;
}


void lcdInit(void)
{
delay5ms();
delay5ms();
delay5ms();
delay5ms();
lcdWriteInstrReg(0x38);
delayms();
lcdWriteInstrReg(0x38);
delay1ms();
lcdWriteInstrReg(0x38);
delay1ms();
lcdWriteInstrReg(0x06);
delay1ms();
lcdWriteInstrReg(0x0f);
delay1ms();
lcdClrScr();
}

void lcdClrScr(void)
{
lcdWriteInstrReg(0x01);
delay1ms();
delay1ms();
}

Make OPORT volatile.

Stefan

void main(void)
{
char ebit,ans;

ebit = 0x01;
ans = ebit*(100/256);
}

how can i display the value in ans on LCD
?

void lcdPutStr (char *string)
{
char i;
i=0;
while(string[i])
{
lcdPutCh (string[i++]);
}
}

this is the program segment for putting the characters into LCD.