f300pwm8_1.c

使用Silicon Labs C8051f300 實現PWM

/*
 **************************************************************************
 *
 * Module         :  PWM of C8051F300
 * File Name      :  F300PWM8_1.c
 * Designed by    :  James Chan
 * Coded by       :  James Chan
 * Tested by      :  
 * Creation Date  :  16 Dec 2005
 * Descriptions   :  PWM demo.
 *                      PWM function setting: 1. 8-Bit Pulse Width Modulator
 *                                            2. 1 channel output
 *                                            3. Base frequency is 1 kHz
 *
 * Copyright (c) 2005 MAXTEK Corporation Taiwan.                            
 * All rights reserved.
 *
 **************************************************************************
 */
/*
 **************************************************************************
 *      
 *      Revision History
 *      ================
 *
 *      Rev     Date                    Who            Description
 * ------------------------------------------------------------------------
 *
 **************************************************************************
 */

/*
 **************************************************************************
 *              Include Files
 **************************************************************************
 */
#include <c8051F300.h>		// SFR declarations

/*
 **************************************************************************
 *              Gobal Constants
 **************************************************************************
 */
#define PWM_START		0x01 		// starting value for the PWM high time
sbit	PWM_OUT = P0^0;				// define PWM output port pin
sbit    SW = P0^3;					// button switch input pin

/*
 **************************************************************************
 *              Variables
 **************************************************************************
 */
unsigned int PWM = PWM_START;	    // Number of PCA clocks for waveform
									// to be high
									// duty cycle = PWM / 256
									// Note: this is a 8-bit value
//
//*************************************************************************
//
// Main Code
//
//*************************************************************************
//


//------------------------------------------------------------------------------------
// Function PROTOTYPES
//------------------------------------------------------------------------------------
void Reset_Source_Init(void)
{
	// disable watchdog timer
	PCA0MD &= ~0x40;				// WDTE = 0 (clear watchdog timer enable)
}

void Oscillator_Init (void)
{
	OSCICN		= 0x06;				// Use internal oscillator to 3.125MHz(SYSCLK / 8)
}

void Port_IO_Init (void)
{
	XBR1 = 0x40;					// Enable crossbar and weak pull-ups
	XBR2 = 0x40;					// Enable CEX0 at P0.0
	P0MDOUT = 0x01;					// P0.0as push-pull output
}

void PCA_Init (void)
{
	// configure the PCA
	PCA0CN = 0x40;					// enable PCA counter
	PCA0MD |= 0x00;					// disable CF interrupt
									// PCA time base = SYSCLK / 12
	// CCM0
	//PCA0CPL0 = 0x8F;			
	PCA0CPH0 = 0x80;
	PCA0CPM0 = 0x42;				// CCM0 in 8-Bit Pulse Width Modulator Mode

	
	// CCM0
	//PCA0CPL0 = 0x8F;			
	PCA0CPH1 = 0x80;
	PCA0CPM1 = 0x42;				// CCM0 in 8-Bit Pulse Width Modulator Mode
}

void Device_Init (void)
{
	Reset_Source_Init();
	Oscillator_Init();
	Port_IO_Init();
	PCA_Init();
}

//------------------------------------------------------------------------------------
// MAIN Routine
//------------------------------------------------------------------------------------
void main (void)
{
	Device_Init();
	while (1)
	{
		// Press the button switch to change to Hi pulse width
		if(SW == 0)
		{
			while(SW == 0);
			//PCA0CPL0 = 0x00;			
			PCA0CPH0 = PWM++;
		    PCA0CPH1 = PWM++;
			
			
		}
	}
}