read_me.txt

This is the simple digital thermometer asm source code.

/*----------------------------------------------------------------
 * File:        TEMP.HEX 
 * 
 * Downloaded from www.hamradioindia.org
 * 
 * Microprocessor PIC16F877A
 * 
 * Purpose:     To display Temperature  between 2 to 100 Degree C
 *
 * Inputs:      LM35
 *             
 * Outputs:     Two seven segment common Cathod LED Display
 *
 * LM35 gives 10mv for a 1 degree temperature change
 *
 * Author: C.V. Niras, [e-mail] 
 *-----------------------------------------------------------------*/

PORTA - pin 2 to 7
------------------
pin 2 (input 1) connected to out put of LM 35
pin 3 (input 2) connected to out put of another LM 35 ( if required )
pin 4, 5 unused
pin 6 conneted to VDD via 10 k resistor and connected to ground by a switch ( to select the two input )
pin 7 unused

PORTB - pin 33 to pin 40
------------------------

The two 7 segment LED's anodes are connected in parellel

pin 40 unused and all other pins connected to 7 segment LED(common cathode) display's 7 anodes via 470 Ohm resistors 7Nos ( pin 33 to segment a , pin 34 segment b,... pin 39 segment g )

PORTC
-----
This posrt is used for to ON/OFF something for the following set temperatures

temperature > 39 
RC 0 (pin15) ON

temperature > 40  
RC1 (pin 16) ON

temperature > 42 
RC2 (pin 17) ON
 
temperature > 50 
RC3 (pin 18) On

temperature < 35 
RC4 (pin 23 ) ON

temperature < 32 
RC5 (pin 24) On

temperature < 30 
RC6 (pin 25) ON

temperature < 25
RC7 (pin 26) ON

PORT E - pin 8 to 10
---------------------

pin 8 unused
pin 9 to the first 7 segment LED's cathode ( ie the digit 10 )

pin 10 to the second 7 segment LED's cathode ( ie the digit 1 )


Other connetctions
------------------
4 Mhz crystal connected between pin 13 and 14, these pins conneced to ground via two 22 pf

pin 1 (MCLR) conneted to VDD with a 10 K resistor to ground by a 10 uF

LM 35
-----
pin 1 GND
pin 2 output
pin 3 VDD 

Notes
-----
 The VDD must be a well regulated 5.0 V 
 The programmer circuit is in http://www.hamradioindia.org?name=Circuits&file=feng