f53xa_timer2_two_8bittimers.c

c8051f52X单片机的定时器的源代码

//-----------------------------------------------------------------------------
// F53xA_Timer2_two_8bitTimers.c
//-----------------------------------------------------------------------------
// Copyright 2007 Silicon Laboratories, Inc.
// http://www.silabs.com
//
// Program Description:
//
// This program presents an example of use of the Timer2 of the C8051F53xA's in
// two 8-bit reload counter/timer mode. It uses the 'F530A TB as the HW
// platform.
//
// It sets the two timers to interrupt every millisecond.
//
// When the timer low interrupts a counter (low_counter) increments and upon
// reaching the value defined by LED_TOGGLE_RATE toggles the LED.
// When the timer high interrupts a counter (high_counter) increments and upon
// reaching the value defined by SIGNAL_TOGGLE_RATE toggles the SIGNAL pin.
//
// Pinout:
//
//    P1.3 -> LED (toggled by TL0)
//
//    P1.7 -> SIGNAL (toggled by TH0)
//
//    all other port pins unused
//
// How To Test:
//
// 1) Open the F53xA_Timer2_two_8bitTimers.c file in the Silicon Labs IDE.
// 2) If desired, change the number of interrupts (ms) to toggle an output:
//    LED_TOGGLE_RATE
//    SIGNAL_TOGGLE_RATE
// 3) Compile the project.
// 4) Download code to a 'F53xA device (either device A or B on the TB).
// 5) Verify the LED jumper is populated (HDR4 for device A and HDR3 for
//    device B).
// 6) If using device A on the TB, verify the P1.7 jumper (J4) is installed.
// 7) Run the code the code.
// 8) Verify that the LED is blinking and SIGNAL is toggling.
//
//
// Target:         C8051F52xA/F53xA (C8051F530A TB)
// Tool chain:     KEIL C51 7.20 / KEIL EVAL C51
// Command Line:   None
//
// Release 1.1
//    -Updated for 'F530A TB (TP)
//    -31 JAN 2008
//
// Release 1.0
//    -Initial Revision (SM)
//    -11 JUN 2007
//

//-----------------------------------------------------------------------------
// Includes
//-----------------------------------------------------------------------------

#include "compiler_defs.h"
#include "C8051F520A_defs.h"

//-----------------------------------------------------------------------------
// Global Constants
//-----------------------------------------------------------------------------

#define SYSCLK             24500000/8  // Internal oscillator frequency in Hz

#define TIMER_PRESCALER            12  // Based on Timer2 CKCON and TMR2CN
                                       // settings

// There areSYSCLK/TIMER_PRESCALER timer ticks per second, so
//SYSCLK/TIMER_PRESCALER/1000 timer ticks per millisecond.
#define TIMER_TICKS_PER_MS SYSCLK/TIMER_PRESCALER/1000

// Note: TIMER_TICKS_PER_MS should not exceed 255 (0xFF) for the 8-bit timers

#define AUX1     TIMER_TICKS_PER_MS
#define AUX2     -AUX1

#define LED_TOGGLE_RATE           100  // LED toggle rate in milliseconds
                                       // if LED_TOGGLE_RATE = 1, the LED will
                                       // be on for 1 millisecond and off for
                                       // 1 millisecond

#define SIGNAL_TOGGLE_RATE         40  // SIGNAL pin toggle rate in
                                       // milliseconds
                                       // if SIGNAL_TOGGLE_RATE = 1, the
                                       // SIGNAL output will be on for 1
                                       // millisecond and off for 1
                                       // millisecond

#define TIMER2_RELOAD_HIGH       AUX2  // Reload value for Timer2 high byte
#define TIMER2_RELOAD_LOW        AUX2  // Reload value for Timer2 low byte

SBIT (LED, SFR_P1, 3);                 // LED='1' means ON
SBIT (SIGNAL, SFR_P1, 7);              // SIGNAL to be used also by Timer2



//-----------------------------------------------------------------------------
// Function Prototypes
//-----------------------------------------------------------------------------

void Oscillator_Init (void);
void Port_Init (void);
void Timer2_Init(void);

//-----------------------------------------------------------------------------
// main() Routine
//-----------------------------------------------------------------------------
void main (void)
{
   PCA0MD &= ~0x40;                    // Disable watchdog timer

   Oscillator_Init ();
   Timer2_Init ();                     // Initialize the Timer0
   Port_Init ();                       // Init Ports
   EA = 1;                             // Enable global interrupts

   while (1);                          // Loop forever

}

//-----------------------------------------------------------------------------
// Initialization Subroutines
//-----------------------------------------------------------------------------

//-----------------------------------------------------------------------------
// Oscillator_Init
//-----------------------------------------------------------------------------
//
// Return Value : None
// Parameters   : None
//
// This function initializes the system clock to use the internal oscillator
// at 24.5/8 MHz.
//
//-----------------------------------------------------------------------------
void Oscillator_Init (void)
{
   OSCICN = 0x84;                      // Set the internal oscillator to
                                       // 24.5/8 MHz
}

//-----------------------------------------------------------------------------
// Port_Init
//-----------------------------------------------------------------------------
//
// Return Value : None
// Parameters   : None
//
// This function configures the crossbar and GPIO ports.
//
// Pinout:
//
//    P1.3 -> LED (toggled by TL0)
//
//    P1.7 -> SIGNAL (toggled by TH0)
//
//    all other port pins unused
//
//-----------------------------------------------------------------------------
void Port_Init (void)
{
   P1MDOUT = 0x88;                     // Set LED and SIGNAL to
                                       // be used as push-pull

   XBR1 = 0xC0;                        // Enable crossbar
}

//-----------------------------------------------------------------------------
// Timer2_Init
//-----------------------------------------------------------------------------
//
// Return Value : None
// Parameters   : None
//
// This function configures Timer2 as two 8-bit reload timers with interrupt.
// Using the internal osc. at 24.5MHz/8 with a timer prescaler of 1:12
// reloading the TMR2H register with TIMER2_RELOAD_HIGH and TMR2L with
// TIMER2_RELOAD_HIGH.
//
// Note: The Timer2 uses a 1:12 prescaler.  If this setting changes, the
// TIMER_PRESCALER constant must also be changed.
//-----------------------------------------------------------------------------
void Timer2_Init(void)
{
   CKCON &= ~0x60;                     // Timer2 usesSYSCLK/12
   TMR2CN &= ~0x01;

   TMR2RLH = TIMER2_RELOAD_HIGH;       // Init Timer2 Reload High register
   TMR2RLL = TIMER2_RELOAD_LOW;        // Init Timer2 Reload Low register

   TMR2H = TIMER2_RELOAD_HIGH;         // Init Timer2 High register
   TMR2L = TIMER2_RELOAD_LOW;          // Init Timer2 Low register

   TMR2CN = 0x2C;                      // Low byte interrupt enabled
                                       // Timer2 enabled
                                       // and Split-Mode enabled
   ET2 = 1;                            // Timer2 interrupt enabled
}


//-----------------------------------------------------------------------------
// Interrupt Service Routines
//-----------------------------------------------------------------------------

//-----------------------------------------------------------------------------
// Timer2_ISR
//-----------------------------------------------------------------------------
//
// This function processes the Timer2 interrupt. It checks both counters for
// matches and, upon a match, toggles the LED and SIGNAL.
//
//-----------------------------------------------------------------------------
void Timer2_ISR (void) interrupt 5
{
   static unsigned int low_counter=0;  // Define counter variables
   static unsigned int high_counter=0;

   if(TF2L == 1)
   {
      if((low_counter++) == LED_TOGGLE_RATE)
      {
         low_counter = 0;              // Reset interrupt counter
         LED = ~LED;                   // Toggle the LED
      }
      TF2L = 0;
   }
   if(TF2H == 1)
   {
      if((high_counter++) == SIGNAL_TOGGLE_RATE)
      {
         high_counter = 0;             // Reset interrupt counter
         SIGNAL = ~SIGNAL;             // Toggle the SIGNAL pin
      }
      TF2H = 0;
   }
}

//-----------------------------------------------------------------------------
// End Of File
//----------------------------------------------------------------------------