ds18b20.c

cvavr ds18b20源程序及仿真的例子,修正了cvavr中显示负温度时出的错误

/* 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
   
   THE ATmega8515 CLOCK FREQUENCY MUST BE 3.6864 MHz

   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.h> // LCD driver routines
#include <ds18b20.h>
#include <delay.h>
#include <stdio.h>

char lcd_buffer[33];


main()
{
//unsigned char i,j,devices;
float aa;
lcd_init(16);
lcd_putsf("CodeVisionAVR\n1 Wire Bus Demo");
delay_ms(2000);
lcd_clear();

    if(ds18b20_init(0,25,35,DS18B20_12BIT_RES)==0)
       {
      
       while (1); /* stop here if init error */
       };

   
while (1)
      {
      //j=1;
      //for (i=0;i<1;i++)
        //  {  
        aa=ds18b20_temperature(0); 
        if(aa>125) 
        sprintf(lcd_buffer,"t=%+.1f\xdfC",aa-4096);
        else
          sprintf(lcd_buffer,"t=%+.1f\xdfC",aa);
          lcd_clear();
          lcd_puts(lcd_buffer);
          delay_ms(500);
          //};
      };
}