f93x_timer0_8bitreloadtimer.c

芯科原厂所有c8051fxx程序的例子。

//-----------------------------------------------------------------------------
// F93x_Timer0_8bitReloadTimer.c
//-----------------------------------------------------------------------------
// Copyright 2007 Silicon Laboratories, Inc.
// http://www.silabs.com
//
// Program Description:
//
// This program presents an example of use of the Timer0 of the C8051F93x in
// 8-bit counter/timer with reload mode. It uses the 'F930DK as HW platform.
// It uses the Timer0 to create an interrupt at a certain rate and when the
// user's interrupt counter reaches the selected value the LED is toggled.
//
// Pinout:
//
//    P1.6 -> LED
//
//    all other port pins unused
//
// How To Test:
//
// 1) Load the F93x_Timer0_8bitReloadTimer.c file in the Silicon Labs IDE.
// 2) If a different LED blink rate is required change the following constant:
//       -> LED_TOGGLE_RATE in milliseconds
// 3) Compile and download code to a 'F336 device
// 4) Verify the LED pins of J8 are populated on the 'F930 TB.
// 5) Run the code
// 6) Check the toggling of the LED (P1.6)
//
//
// Target:         C8051F93x
// Tool chain:     Generic
// Command Line:   None
//
// Release 1.0
//    -Initial Revision (FB)
//    -20 NOV 2007
//
// Note: All time estimates are for SYSCLK freq ~ 20 MHz
//
//-----------------------------------------------------------------------------
// Includes
//-----------------------------------------------------------------------------

#include <compiler_defs.h>
#include <C8051F930_defs.h>            // SFR declarations

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

#define SYSCLK             20000000/8  // SYSCLK in Hz (20 MHz internal
                                       // low power oscillator / 8)
                                       // the low power oscillator has a
                                       // tolerance of +/- 10%
                                       // the precision oscillator has a 
                                       // tolerance of +/- 2%

#define TIMER_PRESCALER            48  // Based on Timer CKCON settings

// There are SYSCLK/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 timer

#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 TIMER0_RELOAD_HIGH       AUX2  // Reload value for Timer0 high byte

SBIT (LED, SFR_P1, 6);                 // LED==1 means ON

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

void Port_Init (void);                 // Port initialization routine
void Timer0_Init (void);               // Timer0 initialization routine
INTERRUPT_PROTO (TIMER0_ISR, INTERRUPT_TIMER0);

//-----------------------------------------------------------------------------
// main() Routine
//-----------------------------------------------------------------------------

void main (void)
{
   PCA0MD &= ~0x40;                    // WDTE = 0 (clear watchdog timer
                                       // enable)
   Timer0_Init ();                     // Initialize the Timer0
   Port_Init ();                       // Init Ports
   EA = 1;                             // Enable global interrupts

   while (1);                          // Loop forever
}

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

//-----------------------------------------------------------------------------
// Port_Init
//-----------------------------------------------------------------------------
//
// Return Value : None
// Parameters   : None
//
// This function configures the crossbar and GPIO ports.
//
// P1.6   digital  push-pull  LED
//
//-----------------------------------------------------------------------------
void Port_Init (void)
{
   XBR2 = 0x40;                        // Enable crossbar
   P1MDOUT = 0x40;                     // Set LED
}

//-----------------------------------------------------------------------------
// Timer0_Init
//-----------------------------------------------------------------------------
//
// Return Value : None
// Parameters   : None
//
// This function configures the Timer0 as a 8-bit timer with reload, interrupt
// enabled.
// Using the internal osc. at 24.5MHz with a prescaler of 1:8 and reloading
// TL0 register with TH0 it will interrupt aproximately one time every 1msec.
//
// Note: The Timer0 uses a 1:48 prescaler.  If this setting changes, the
// TIMER_PRESCALER constant must also be changed.
//-----------------------------------------------------------------------------
void Timer0_Init(void)
{
   TH0 = TIMER0_RELOAD_HIGH;           // Init Timer0 High register
   TL0 = TH0;                          // Set the intial Timer0 value

   TMOD = 0x02;                        // Timer0 in 8-bit reload mode
   CKCON = 0x02;                       // Timer0 uses a 1:48 prescaler
   ET0=1;                              // Timer0 interrupt enabled
   TCON = 0x10;                        // Timer0 ON
}


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

//-----------------------------------------------------------------------------
// Timer0_ISR
//-----------------------------------------------------------------------------
//
// Here we process the Timer0 interrupt and toggle the LED when appropriate
//
//-----------------------------------------------------------------------------
INTERRUPT (TIMER0_ISR, INTERRUPT_TIMER0)
{
   static int counter = 0;

   if((counter++) == LED_TOGGLE_RATE)
   {
      LED = !LED;                      // Toggle the LED
      counter = 0;
   }
}

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