keil开发arm例程

				/*****************************************************************************
				 *   pwm.c:  PWM module file for Philips LPC214x Family Microprocessors
				 *
				 *   Copyright(C) 2006, Philips Semiconductor
				 *   All rights reserved.
				 *
				 *   History
				 *   2005.10.01  ver 1.00    Prelimnary version, first Release
				 *
				******************************************************************************/
				#include "LPC214x.H"                        /* LPC21xx definitions */
				#include "type.h"
				#include "irq.h"
				#include "timer.h"
				#include "pwm.h"
				
				DWORD match_counter;
				
				/******************************************************************************
				** Function name:		PWMHandler
				**
				** Descriptions:		PWM interrupt handler
				**				For now, it only deals with PWM match 0
				**
				** parameters:			None
				** Returned value:		None
				** 
				******************************************************************************/
				void PWMHandler (void) __irq 
				{
				    DWORD regVal;
				
				    regVal = PWMIR;
				    IENABLE;			/* handles nested interrupt */
				    if ( regVal & MR0_INT )
				    {
					match_counter++;	
				    }
				    PWMIR |= regVal;		/* clear interrupt flag on match 0 */
				    IDISABLE;
				    VICVectAddr = 0;		/* Acknowledge Interrupt */
				}
				
				/******************************************************************************
				** Function name:		PWM_Init
				**
				** Descriptions:		PWM initialization, setup all GPIOs to PWM0~6,
				**				reset counter, all latches are enabled, interrupt
				**				on PWMMR0, install PWM interrupt to the VIC table.
				**
				** parameters:			Duty cycle
				** Returned value:		true or fase, if VIC table is full, return false
				** 
				******************************************************************************/
				DWORD PWM_Init( DWORD cycle )
				{
				    match_counter = 0;
				    PINSEL0 = 0x000A800A;	/* set GPIOs for all PWMs */
				    PINSEL1 = 0x00000400;
				
				    PWMTCR = TCR_RESET;		/* Counter Reset */ 
						
				    PWMPR = 0x00;		/* count frequency:Fpclk */
				    PWMMCR = PWMMR0I | PWMMR0R;	/* interrupt on PWMMR0, reset on PWMMR0, reset 
								TC if PWM0 matches */				
				    PWMMR0 = cycle;		/* set PWM cycle */
				    PWMMR1 = cycle * 5/6;
				    PWMMR2 = cycle * 2/3;
				    PWMMR3 = cycle * 1/2;
				    PWMMR4 = cycle * 1/3;
				    PWMMR5 = cycle * 1/6;	
				
				    /* all PWM latch enabled */
				    PWMLER = LER0_EN | LER1_EN | LER2_EN | LER3_EN | LER4_EN | LER5_EN | LER6_EN;
				
				    if ( install_irq( PWM0_INT, (void *)PWMHandler ) == FALSE )
				    {
					return (FALSE);
				    }
				    return (TRUE);
				}
				
				/******************************************************************************
				** Function name:		PWM_Set
				**
				** Descriptions:		PWM cycle setup
				**
				** parameters:			PWM cycle and offset
				** Returned value:		None
				** 
				******************************************************************************/
				void PWM_Set( DWORD cycle, DWORD offset )
				{			
				    PWMMR0 = cycle;		/* set PWM cycle */
				    PWMMR1 = cycle * 5/6 + offset;
				    PWMMR2 = cycle * 2/3 + offset;
				    PWMMR3 = cycle * 1/2 + offset;
				    PWMMR4 = cycle * 1/3 + offset;
				    PWMMR5 = cycle * 1/6 + offset;
				
				    /* The LER will be cleared when the Match 0 takes place, in order to
				    load and execute the new value of match registers, all the PWMLERs need to
				    reloaded. all PWM latch enabled */
				    PWMLER = LER0_EN | LER1_EN | LER2_EN | LER3_EN | LER4_EN | LER5_EN | LER6_EN;    
				    return;
				}
				
				/******************************************************************************
				** Function name:		PWM_Start
				**
				** Descriptions:		Enable PWM by setting the PCR, PTCR registers
				**
				** parameters:			None
				** Returned value:		None
				** 
				******************************************************************************/
				void PWM_Start( void )
				{
				    /* All single edge, all enable */
				    PWMPCR = PWMENA1 | PWMENA2 | PWMENA3 | PWMENA4 | PWMENA5 | PWMENA6;
				    PWMTCR = TCR_CNT_EN | TCR_PWM_EN;	/* counter enable, PWM enable */
				    return;
				}
				
				/******************************************************************************
				** Function name:		PWM_Stop
				**
				** Descriptions:		Stop all PWM channels
				**
				** parameters:			None
				** Returned value:		None
				** 
				******************************************************************************/
				void PWM_Stop( void )
				{
				    PWMPCR = 0;
				    PWMTCR = 0x00;		/* Stop all PWMs */
				    return;
				}