Svenska ElektronikForumet

Kod: Markera allt

//******************************************************************************
// microcontroller : P16F877A
//
// Project: onewire
// This project is designed to work with PIC 16F877A;
// with minor adjustments, it should work with any other PIC MCU
//
// The code demonstrates one-wire communication with temperature sensor DS1820
// connected to RA5 pin.
// After reset, PIC obtaines temperature from sensor and prints it on LCD.
//******************************************************************************

// Set TEMP_RESOLUTION to the corresponding resolution of your DS18x20 sensor:
//  18S20: 9
//  18B20: 12 (default setting; can be 9,10,11,or 12)
const unsigned short TEMP_RESOLUTION = 12;

const int RES_FACTOR_1[4] = {5000, 2500, 1250, 625};
const unsigned int RES_FACTOR_2[4] = {0x0001, 0x0003, 0x0007, 0x000F};
const unsigned int RES_FACTOR_3[4] = {0x8000, 0xC000, 0xE000, 0xF000};

unsigned temp;
unsigned short  j, RES_SHIFT;

void Display_Temperature(unsigned int temp) {
  const unsigned short RES_SHIFT = TEMP_RESOLUTION - 8;
  unsigned int temp_whole, temp_fraction;
  unsigned short i;
  char text[8];

  // Isolate the fraction and make it a 4-digit decimal integer (for display)
  temp_fraction = temp & RES_FACTOR_2[RES_SHIFT - 1];
  temp_fraction = temp_fraction * RES_FACTOR_1[RES_SHIFT - 1];
  //portc = temp_fraction;
  // Handle the whole part of temperature value
  temp_whole = temp;

  // Is temperature negative?
  if ((temp_whole & 0x8000) != 0u) i = 1;  // Yes, i = 1
  else i = 0;                             // No,  i = 0
  portc = i;
  // Remove the fractional part
  temp_whole >>= RES_SHIFT;

  // Correct the sign if necessary
  if (i) temp_whole |= RES_FACTOR_3[RES_SHIFT - 1];

  //portd = temp_whole;
  IntToStr(temp_whole, text);  // Convert whole part to string
  LCD_Out(2, 6, text);         // Print whole part on LCD
  LCD_Chr_CP('.');             // Print dot to separate fractional part


  IntToStr(temp_fraction, text); // Convert fractional part to string

  // Add leading zeroes (we display 4 digits fractional part)
  if (temp_fraction < 1000u) LCD_Chr_CP('0');
  if (temp_fraction < 100u)  LCD_Chr_CP('0');
  if (temp_fraction < 10u)   LCD_Chr_CP('0');
  
  LCD_Out_CP(text);            // Print fractional part on LCD

  LCD_Chr_CP(223);             // Print degree character
  LCD_Chr_CP('C');             // Print 'C' for Centigrades
}//~

void main() {
  ADCON1 = 0xFF;               // Configure RA5 pin as digital I/O
  PORTE  = 0xFF;
  TRISE  = 0x0F;               // PORTE is input
  PORTB  = 0;
  TRISB  = 0;                  // PORTB is output
  TRISD = 0 ;
  TRISC = 0 ;
  // Initialize LCD on PORTB and prepare for output
  LCD_Init(&PORTB);
  LCD_Cmd(LCD_CURSOR_OFF);
  LCD_Out(1, 1, " Temperature:   ");

  do { // main loop

    OW_Reset(&PORTE,2);        // Onewire reset signal
    OW_Write(&PORTE,2,0xCC);   // Issue command SKIP_ROM
    OW_Write(&PORTE,2,0x44);   // Issue command CONVERT_T
    Delay_us(120);
    
    OW_Reset(&PORTE,2);
    OW_Write(&PORTE,2,0xCC);   // Issue command SKIP_ROM
    OW_Write(&PORTE,2,0xBE);   // Issue command READ_SCRATCHPAD
    Delay_ms(400);
       
    j = OW_Read(&PORTE,2);     // Get temperature LSB
    temp = OW_Read(&PORTE,2);  // Get temperature MSB
    //portc = temp;
    //portd = j;
    temp <<= 8; temp += j;     // Form the result
    Display_Temperature(temp); // Format and display result on LCD
    Delay_ms(500);
    
  } while (1);


}//~!