STM32——PWM

#define TIMER4_PWM_GRP      GPIOB
#define TIMER4_PWM_INDEX1    GPIO_Pin_7
#define TIMER4_PWM_INDEX2    GPIO_Pin_6
#define TIMER4_PWM_LOW(grp, index) GPIO_ResetBits(grp, index)
#define TIMER4_PWM_HIGH(grp, index) GPIO_SetBits(grp, index)
#define TIMER4_PWM_CONFIG(grp, index, mode) GPIOConfig(grp, index, mode)

#ifndef _BSP_PWM_H_
#define _BSP_PWM_H_

#include "stm32f10x_gpio.h"
#include "stm32f10x_tim.h"
#include "type.h"

void PwmTimerSet(GPIO_TypeDef* gpio, uint16_t pin, TIM_TypeDef* timer, uint8_t channel,
                 uint32_t freq, uint32_t duty);

#endif /* _BSP_PWM_H_ */

#include "pwm.h"
//#include "target.h"

void pwm_gpio_init(GPIO_TypeDef* gpio, uint16_t pin, GPIOMode_TypeDef mode)
{
  RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM4, ENABLE);
  if(mode == GPIO_Mode_AF_PP)
  {
    RCC_APB2PeriphClockCmd(RCC_APB2Periph_AFIO, ENABLE);
  }
  TIMER4_PWM_CONFIG(gpio, pin, mode);
}

// set freq(Hz) and duty(1/10000); if duty = 2000--- 2000/10000 = 20%
// PwmTimerSet(TIMER4_PWM_GRP, TIMER4_PWM_INDEX1, PWM_TIMER4, 1, 10000, 5000);
void PwmTimerSet(GPIO_TypeDef* gpio, uint16_t pin, TIM_TypeDef* timer, uint8_t channel,
                 uint32_t freq, uint32_t duty)
{
  TIM_TimeBaseInitTypeDef  TIM_TimeBaseStructure;
  TIM_OCInitTypeDef  TIM_OCInitStructure;

  uint16_t period, prescal;
  uint32_t clk;

  if(10000 == duty) // 100%
  {
    TimerDisable(timer);
	pwm_gpio_init(gpio, pin, GPIO_Mode_Out_PP);
	TIMER4_PWM_LOW(gpio, pin);

	return;
  }

  pwm_gpio_init(gpio, pin, GPIO_Mode_AF_PP);

  clk = SystemCoreClock; // 72 * 10^6;

  if(freq < 100)
  {
    prescal = 100 - 1;
    period = (clk / 10000) / freq - 1;
  }
  else if(freq < 3000)
  {
    prescal = 100 - 1;
    period = (clk / 100) / freq - 1;
  }
  else
  {
    prescal = 0;
    period = clk / freq - 1;
  }

  TIM_TimeBaseStructure.TIM_Period = period;
  TIM_TimeBaseStructure.TIM_Prescaler = prescal;
  TIM_TimeBaseStructure.TIM_ClockDivision = 0;
  TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;
  TIM_TimeBaseStructure.TIM_RepetitionCounter = 0;
  TIM_TimeBaseInit(timer, &TIM_TimeBaseStructure);

  TIM_OCStructInit(&TIM_OCInitStructure);

  TIM_OCInitStructure.TIM_OCMode = TIM_OCMode_PWM1;
  TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable;
  TIM_OCInitStructure.TIM_Pulse = (duty * period) / 10000;
  TIM_OCInitStructure.TIM_OCPolarity = TIM_OCPolarity_High;

  if(1 == channel)
  {
    TIM_OC1Init(timer, &TIM_OCInitStructure);
    TIM_OC1PreloadConfig(timer, TIM_OCPreload_Enable);
  }
  else if(2 == channel)
  {
    TIM_OC2Init(timer, &TIM_OCInitStructure);
    TIM_OC2PreloadConfig(timer, TIM_OCPreload_Enable);
  }
  TIM_ARRPreloadConfig(timer, ENABLE);

  /* TIMx enable counter */
  TIM_Cmd(timer, ENABLE);
}