bsp_pwm4c.c

IAR 平台ATMEL 的例程, 和说明

/*-----------------------------------------------------------------------------
*   EUROPE TECHNOLOGIES Software Support
*------------------------------------------------------------------------------
* The software is delivered "AS IS" without warranty or condition of any
* kind, either express, implied or statutory. This includes without
* limitation any warranty or condition with respect to merchantability or
* fitness for any particular purpose, or against the infringements of
* intellectual property rights of others.
*------------------------------------------------------------------------------
*
* Processor   : easyCAN
* File Name   : bsp_pwm4c.c
* Description : Function declarations for PWM for the BSP
* Version     : 1.01
*
*       +----- (NEW | MODify | ADD | DELete)                                 
*       |                                                                    
*  No   |   when       who                what               
*-----+---+----------+------------------+--------------------------------------
* 000  NEW  01/05/99   Patrice VILCHEZ    Creation
* 001  MOD  01/04/01   Olivier MAZUYER    Clean up
* 002  MOD  31/01/02   Mahmoud Mesgarzadeh   Clean Up
*----------------------------------------------------------------------------*/


/******************************************************************************
* Includes 
******************************************************************************/
#include "csp.h"
#include "bsp.h"


/******************************************************************************
Function          : BSP_PWM4CSetOuput
Description       : Set the pwm4c system to a particular 
                    frequency and dutycycle.
Input             : *pwm4c, frequency, dutycycle
Functions called  : CSP_PWMInit, CSP_PWMStart, CSP_PWMSetOffstate
Returns           : None
******************************************************************************/
void BSP_PWM4CSetOuput(CSP_PWM4C_T *pwm4c, U8_T channel_u8, U32_T frequency_u32, U16_T dutycycle_u16)
{
  /* local variables */
  U8_T  i_u8 = 0;
  U32_T delay_u32;
  U32_T pulse_u32;
  U32_T mode_u32;
  U32_T clk_u32;

  /* Switch On PWM Controller (To be sure) */
  CSP_PWM4C_SET_ECR(pwm4c, PWM); 

  /* Clear Current Clock Divider */
  CSP_PWM4C_SET_MR(pwm4c, CSP_PWM4C_GET_MR(pwm4c) & ~(0x1F << (channel_u8 * 8)));
    
  if( frequency_u32 != 0 )
  {
     /* Define delay & pulse function(frequency/dutycycle/prescalar) */
     clk_u32     = (BSP_SYSTEM_CLOCK / 2);
     delay_u32   = ((clk_u32 * dutycycle_u16) / frequency_u32);
     pulse_u32   = (clk_u32 / (frequency_u32/256)) - delay_u32;
  
     /* Condition about cycle of clock */
     while((delay_u32 > 0xFFFF) | (pulse_u32 > 0xFFFF))
     {
        /*  Compute delay_u32 & pulse_u32, increment i_u8 and divide clk_u32 */
        i_u8++;
        clk_u32 /= 2;
        /* Define delay & pulse function(frequency/dutycycle/prescalar)*/
        delay_u32   = ((clk_u32 * dutycycle_u16) / frequency_u32);
        pulse_u32   = (clk_u32 / (frequency_u32/256)) - delay_u32;
     }
   /* Define Mode */
     mode_u32 = i_u8;

     /* Init PWM Module */
     CSP_PWM4CInit(pwm4c);
     CSP_PWM4CConfigureChannel(pwm4c, channel_u8, mode_u32, (U16_T) delay_u32, (U16_T) pulse_u32);

     /* start PWM Module */
     CSP_PWM4CEnable(pwm4c , channel_u8);
   }
   else
   {
     /* Stop PWM Module */
     if( dutycycle_u16 == 100 )
     {
         CSP_PWM4CSetOffstate(pwm4c, 1, channel_u8);
     }
     else
     {
         CSP_PWM4CSetOffstate(pwm4c, 0, channel_u8);
     }
   } 
}