digital thermometer with 8051

[Shane Culhane]

hi,im am building a digital thermometer with 8051 and am seeking help…rough ideas = inputs of thermistor and keypad to change max/min temp for alarm to go off,ADC,microcontroller (AT89C51),outputs of LED showing Fan goes on/off if temp goes over max/min and display with temp 

[Amol Shah]

Quite simple dude use LM35 because its o/p is linear and you can calibrate it easily.

For ADC you can use ADC0804 single channel 8 bit ADC.

For keypad even two switches are sufficient one for increment and another for decrement.

Instead of showing lights on/off on led use a relay, you will require relay driver circuit to drive the relay using which you can acutually turn on/off fan. check this link for relay driver circuit: http://www.dnatechindia.com/Tutorial/8051-Tutorial/Interfacing-Relay-to-Microcontroller.html

[Shane Culhane]

Thanks Amol Shah for your help….im a beginner to this so my knowledge is slim,any ideas on display to be used…..im also dreading the code,C ++ is best i believe?

[Amol Shah]

You can use 16×2 alphanumeric display….its very simple to interface…check this link to know how to interface lcd to 8051 controller: http://www.dnatechindia.com/Tutorial/8051-Tutorial/Interfacing-LCD-to-8051.html

 

here is a link for code in C language: http://www.dnatechindia.com/Code-Library/C-Code-Library/LCD-INTERFACING-TO-8051-IN-8-BIT-MODE.html

 

and here is a link for code in assembly language: http://www.dnatechindia.com/Code-Library/8051-Assembly/LCD-Interfacing-To-8051-in-8-bit-mode.html

[Shane Culhane]

made attempt at code and isis

 

 

#include <reg52.h>

 

#define upper 22

#define lower 17

#define ON 1

#define OFF 2

 

unsigned char a2d_val;

 

sbit fan = P2^0;

sbit heater = P2^1;

sbit start_con = P3^0;

sbit eoc = P3^7;

 

void delay_50 (void);

 

void main (void)

{

eoc = 1;

P1 = 0xFF;

fan = heater = OFF;

while (1)

{

start_con = 1;

start_con = 0;

while (eoc == 0)

{

}

a2d_val = P1;

if (a2d_val > upper)

{

fan = ON;

heater = OFF;

}

else if (a2d_val<lower)

{

fan = OFF;

heater = ON;

}

else 

{

fan = heater = OFF;

}

delay_50();

}

}

void delay_50 (void)

{

TMOD = 0x01;

TL0 = 0x60;

TH0 = 0x3c;

TF0 = 0;

TR0 = 1;

while (TF0 == 0)

{

}

TR0 = 0;

}

 

 

 

 

code worked i think but problems building it

 

 

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