I recently finished a program that uses DS1820 temperature sensor with PIC16F877 to measure its whole range -ve and +ve.
But I don't know how to read a temp. in the code itself, as I just (copy & paste it) slightly modified it from the internet to be able to run on PIC16F877 (I tried the code in MikroC program's Help, but didn't work on Proteus ISIS) .
I want (porta.b5 = 1) when the temp. is +5°C, else porta.b5=0
The problem is I don't understand how the code is running, I tried (text[2] == 5) porta.b5=1, and it didn't work (as text is an array of char)

Here is the code:

sbit LCD_RS at RC4_bit;
sbit LCD_EN at RC5_bit;
sbit LCD_D4 at RC0_bit;
sbit LCD_D5 at RC1_bit;
sbit LCD_D6 at RC2_bit;
sbit LCD_D7 at RC3_bit;
sbit LCD_RS_Direction at TRISC4_bit;
sbit LCD_EN_Direction at TRISC5_bit;
sbit LCD_D4_Direction at TRISC0_bit;
sbit LCD_D5_Direction at TRISC1_bit;
sbit LCD_D6_Direction at TRISC2_bit;
sbit LCD_D7_Direction at TRISC3_bit;
unsigned short C_Neg=0;
char *text = "000.0000";
unsigned temp, templ, temph;
unsigned int temp2write, tempinc, temp_fraction;
char temp_whole;
void main()
{
 trisc = 0;
 portc = 0;
 trisa = 1;
 porta.b0 = 0;
 ADCON1 = 7; // Configure AN pins as digital I/O
 Lcd_Init(); // Lcd_Init_EP4, see Autocomplete
 Lcd_Cmd(_LCD_CURSOR_OFF);
 Lcd_Out(1, 1, " Temperature: ");
 // Print degree character, 'C' for Centigrades
 Lcd_Chr(2,13,223);
 Lcd_Chr(2,14,'C');
    OPTION_REG = 0x00;   // Clear INTEDG, External Interrupt on falling edge
    INTCON.INTF = 0;     // Clear interrupt flag prior to enable
    INTCON.INTE = 1;     // enable INT interrupt
    INTCON.GIE  = 1;     // enable Global interrupts
    //--- main loop
    while (1)
    {
    //--- perform temperature reading
    Ow_Reset(&PORTa,0); // Onewire reset signal
    Ow_Write(&porta,0,0xCC); // Issue command SKIP_ROM
    Ow_Write(&porta,0,0x44); // Issue command CONVERT_T
    INTCON.GIE  = 1;     // 1-wire library disables interrpts
    Delay_ms(750);
    Ow_Reset(&porta,0);
    Ow_Write(&porta,0,0xCC); // Issue command SKIP_ROM
    Ow_Write(&porta,0,0xBE); // Issue command READ_SCRATCHPAD
    templ = Ow_Read(&porta,0);
    TempH = Ow_Read(&PORTA, 0);
    temp = (temph << 8) + templ;   //temp(temp_value)
     // check if temperature is negative
    if (temp & 0x8000) 
    {
      C_Neg = 1;
      text[0] = '-';  //text(tempc)
      temp = ~temp + 1;     //temp(temp_value)
    }
    else C_Neg = 0;
    // extract temp_whole
    temp_whole = temp >> 1;
    if (temp & 0x0001)
    {  // LSB is 0.5C
       temp_fraction = 5;
    }
    else temp_fraction = 0;
    tempinc = temp_whole*10+temp_fraction;
    // convert temp_whole to characters
   if (!C_Neg) 
   {
    if (tempinc/1000) text[0] = tempinc/1000 +48;
    else text[0] = ' ';
   }
   text[1] = (tempinc/100)%10 + 48; // extract tens digit
   text[2] = (tempinc/10)%10 + 48; // extract ones digit
   text[4] =  tempinC%10  + 48;
   Lcd_Out(2, 5, text);
 }
}

 

it looks like the variable temp_whole. Holds the value you are looking for. If this value is greater or equal to 5 turn on your LED.

 

I tried that but nothing happens, and I tried to write it on the LCD and nothing appears.
I need to covert array(text) to a variable with its sign, then convert it to string to be displayed on LCD.