Timer

Related SFR

• TMOD (Timer Mode) * Select whether you want a timer or a counter * Set a timer to be 8-bit, double 8-bit, 13-bit, or 16-bit timer

• CKCON (Clock Config) * Select whether the clock source is from internal or external * Whether to use the original clock or clock/12

• TCON (Timer Config) * Start/Stop timer/counter * Check whether there is an interrupt flag for certain timer * Determine whether a timer/counter is edge triggered or level triggered

• TLx/THx (Timer Lower/Higher Bytes) * A register storing the value of timer/counter with index x

Typical Code

// Timer Initialization function
void timer_init(){
  // select the clock source
  CKCON &= ~0x08; /* Timer 0 uses SYSCLK/12 as source */

  // select timer and set the working mode
  TMOD &= 0xF0; /* Clear bits 0-3 of the Timer Mode Register */
  TMOD |= 0x01; /* Set Timer 0 to Mode 1 (16-bit counter/timer) */

  // stop timer
  TR0 = 0; /* Disable Timer 0 */

  TMR0 = 0; /* Clear all 16 bits of Timer 0’s count */
  // TL0 = 0; TH0 = 0; /* Or Clear low & high bytes of Timer 0 separately */

}

// in the function where you want to use your timer
TR0 = 1; // enable timer 0

The Interrupt Service Routines read as

void ISR_name(void) __interrupt 1
{
  // the interrupt order of timer 0 is 1. These values can be found in "Interrupts Priority Table"
  // Put code here
}