Search Results - microcontroller

I am doing a project which requires that I turn on and off two LED’s independently from a computer using serial port communication. I send a character like ‘A’ via the serial port and turn on one LED for say 1 minute and send another character like ‘B’ and turn on another LED for 2 minutes. My problem is that when using Timer0 of pic 18F87k22, I can’t implement the 1 minute and 2 minute delays independently. When I turn on the one LED the other one doesn’t respond and vice versa. I am simulating using Proteus and my code is is in MikroC as shown below:

char uart_rd;
char cnt;

void interrupt () 
{
  if (TMR0IF_bit) 
  {
     cnt++;                 // increment counters
     TMR0IF_bit = 0;        // clear TMR0IF

     TMR0L = 0xDC;             // set TMR0 for aproximetly 1 sec
     TMR0H = 0x0B;
  }
}

void one_min_delay () 
{
  TRISB  = 0;              // PORTB is output
  TMR0H = 0x0B;
  TMR0L = 0xDC;               // Timer0 initial value

  T0CON = 0x84;            // Set TMR0 to 8bit mode and prescaler to 256
  GIE_bit = 1;             // Enable global interrupt
  TMR0IE_bit = 1;          // Enable Timer0 interrupt

  cnt = 0;                 // Initialize cnt

  do 
  {
    if (cnt >= 60) 
    {
      LATB = 0x00;      // turnoff PORTB LEDs
      cnt = 0;             // Reset cnt
    }
  }while(1);
}

void two_min_delay () 
{
  TRISB  = 0;              // PORTB is output
  TMR0H = 0x0B;
  TMR0L = 0xDC;               // Timer0 initial value
  T0CON = 0x84;            // Set TMR0 to 8bit mode and prescaler to 256
  GIE_bit = 1;             // Enable global interrupt
  TMR0IE_bit = 1;          // Enable Timer0 interrupt

  cnt = 0;                 // Initialize cnt

  do 
  {
    if (cnt >= 120) 
    {
      LATB = 0x00;      // turnoff PORTB LEDs
      cnt = 0;             // Reset cnt
    }
  }while(1);
}

void main() 
{
  UART1_Init(9600);               // Initialize UART module at 9600 bps
  Delay_ms(100);                  // Wait for UART module to stabilize
  TRISB = 0x00;

  while (1) 
  {
    if (UART1_Data_Ready()) 
    {     // If data is received,
      uart_rd = UART1_Read();
    }

    if (uart_rd=='A')   
    {
      LATB = 0x01;
      one_min_delay();
    }
    else if (uart_rd == 'B')   
    {
      PORTB = 0x02;
      two_min_delay ();
    }
    uart_rd ='\0';
  }
}