[SOLVED] Design of a PIC12F683 based temperature controlled DC fan

/*
 * Project name:
     Design of a PIC12F683 based temperature controlled DC fan
 * Revision History:
      29th September 2015:
       - initial release (omega6)[url] https://www.edaboard.com/threads/343938/[/url]
      09th October 2015:
       - modified release (Philippe LE GUEN) [url]https://pleguen.fr/[/url]
 * Description:
      A simple example of using the ADC library.
      ADC results is used to command a fan motor (DC 12V).
 * Test configuration:
     MCU:             PIC12F683
                      [url]https://ww1.microchip.com/downloads/en/DeviceDoc/41211D_.pdf[/url]
     dev.board:       EasyPIC7
                      [url]https://www.mikroe.com/easypic/[/url]
     Oscillator:      Internal Oscillator (HFINTOSC), 8.0000 MHz (no crystal)
     Ext. Modules:    a DC12V motor fan
     SW:              mikroC PRO for PIC
                      [url]https://www.mikroe.com/mikroc/pic/[/url]
 * NOTES:
     - The motor fan is supply by a +12V auxiliary, commanded by a transistor NPN BC547 with the PWM signal on GP2.
 */


//const unsigned short VREF = 5.0;                         // The current value is +5,0V, so is equal to +5000mV...
const unsigned short VREF = 4.90;                          // Warning ! The VDD power on EaysiPIC7 is 4,90V (measured)
unsigned int adc_sample, Temp_C, Temp_Old, offset;

void main() {

  ADC_Init();                                              // Initialize ADC
  ADCON0 = 0b10000011;                                     // Set VDD as Vref, ANO as analog read, Right justified (very important for a good AD Conversion !)
  ANSEL = 0b00110000;                                      // bit 6-4 ADCS<2:0>: A/D Conversion Clock Select bits (see datasheet)
                                                           //   x11 = FRC (clock derived from a dedicated internal oscillator = 500 kHz max)
  TRISIO.B0 = 1;                                           // Set pin 7 (ANO) as input, used for ADC read
  TRISIO.B2 = 0;                                           // Set pin 5 (CCP1) as output, used for PWM

  PWM1_Init(5000);                                         // Initialize PWM at 19.61kHz (per pic spec-sheet allows 10bit resolution)
  PWM1_Start();

  while(1){
    //Read ADC Channel 1
    adc_sample = ADC_Get_Sample(0);                        // Get 10-bit results of AD conversion
    //adc_sample = ADC_Read(0);
                                  // for indication, VREF is a value in Volt...
    Temp_C = (adc_sample * VREF)/10.240;                   // Calculate temperature in Celsuis
                                                           // The LM35 delivers +246mV at room temperature of +22.7°C case (measured)
                                                           //  which corresponds to +10,83700441mV/°C (10mV/°C in theory), due to component tolerance...
    if(Temp_C != Temp_Old) {

      //if(Temp_C >= 30)
      if(Temp_C > 21) {
         PWM1_Set_Duty(255);                               // Set PWM to 100%
      }
      
      /*if(20 <= Temp_C <= 21) {                           // you can adapted this code for your application testing... (is perfectible)
         PWM1_Set_Duty(127);
      }*/

      else
      if(Temp_C < 20) {
         PWM1_Set_Duty(0);                                 // Turn off PWM
      }

      Temp_Old = Temp_C;

    }

    Delay_ms(500);
  }

}