www.pudn.com > DS18B20.rar > ds18b20__.c

/* Multipoint thermometer with LCD display 
   using the Maxim DS18B20 
   1 Wire bus temperature sensors 
 
   CodeVisionAVR C Compiler 
   (C) 2000-2005 HP InfoTech S.R.L. 
   www.hpinfotech.ro 
 
   Chip: ATmega8515 
   Memory Model: SMALL 
   Data Stack Size: 128 bytes 
 
   PLEASE MAKE SURE THAT THE CKSEL0..3 FUSE 
   BITS ARE PROGRAMMED TO USE THE EXTERNAL 
   3.6864MHz CLOCK SOURCE OF THE STK500 AND NOT 
   THE INTERNAL 1MHz OSCILLATOR. 
   The ATmega8515 chip comes from the factory 
   with CKSEL0..3 fuse bits set to use the 
   internal 1 MHz oscillator. 
 
   The DS18B20 sensors are connected to 
   bit 6 of PORTA of the ATmega8515 as follows: 
 
   [DS18B20]     [STK500 PORTA HEADER] 
    1 GND         -   9  GND 
    2 DQ          -   7  PA6 
    3 VDD         -  10 +5V 
 
   All the temperature sensors must be connected 
   in parallel 
 
   AN 4.7k PULLUP RESISTOR MUST BE CONNECTED 
   BETWEEN DQ (PA6) AND +5V ! 
*/ 
#asm 
    .equ __w1_port=0x1b 
    .equ __w1_bit=6 
#endasm 
 
/* Use an 2x16 alphanumeric LCD connected 
   to PORTC as follows: 
 
  [LCD]   [STK500 PORTC HEADER] 
   1 GND- 9  GND 
   2 +5V- 10 VCC 
   3 VLC- LCD contrast control voltage 0..1V 
   4 RS - 1  PC0 
   5 RD - 2  PC1 
   6 EN - 3  PC2 
  11 D4 - 5  PC4 
  12 D5 - 6  PC5 
  13 D6 - 7  PC6 
  14 D7 - 8  PC7 
*/ 
 
#asm 
    .equ __lcd_port=0x15 
#endasm 
 
#include  // LCD driver routines 
#include  
#include  
#include  
 
char lcd_buffer[33]; 
 
/* maximum number of DS18B20 connected to the 1 Wire bus */ 
#define MAX_DEVICES 8 
 
/* DS18B20 devices ROM code storage area */ 
unsigned char rom_code[MAX_DEVICES][9]; 
 
main() 
{ 
unsigned char i,j,devices; 
float tmp; 
lcd_init(16); 
lcd_putsf("CodeVisionAVR\n1 Wire Bus Demo"); 
delay_ms(200); 
lcd_clear(); 
 
/* detect how many DS18B20 devices 
   are connected to the 1 Wire bus */ 
devices=w1_search(0xf0,rom_code); 
sprintf(lcd_buffer,"%u DS18B20\nDevice detected",devices); 
lcd_puts(lcd_buffer); 
delay_ms(800); 
 
/* display the ROM codes for each device */ 
if (devices) 
   { 
   for (i=0;i125) 
          sprintf(lcd_buffer,"t%u=%+.3f\xdfC",i+1,tmp-4096); 
          else 
          sprintf(lcd_buffer,"t%u=%+.3f\xdfC",i+1,tmp); 
          lcd_clear(); 
          lcd_puts(lcd_buffer); 
          delay_ms(1000); 
          }; 
      }; 
}