#include "pwm.h"
#include "led.h"


//PWM输出初始化
//arr：自动重装值
//psc：时钟预分频数
void PWM_Init(u16 arr,u16 psc)
{  
	GPIO_InitTypeDef GPIO_InitStructure;
	TIM_TimeBaseInitTypeDef  TIM_TimeBaseStructure;
	TIM_OCInitTypeDef  TIM_OCInitStructure;

	RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM3, ENABLE);
 	RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA  | RCC_APB2Periph_AFIO, ENABLE);  //使能GPIO外设和AFIO复用功能模块时钟使能
	                                                                         	 //用于TIM3的CH2输出的PWM通过该LED显示
					
	GPIO_InitStructure.GPIO_Pin = GPIO_Pin_8;
	GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IN_FLOATING;
	GPIO_Init(GPIOA, &GPIO_InitStructure);

   //设置该引脚为复用输出功能,输出TIM3 CH2的PWM脉冲波形
	GPIO_InitStructure.GPIO_Pin = GPIO_Pin_7; //TIM_CH2
	GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP;  //复用推挽输出
	GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
	GPIO_Init(GPIOA, &GPIO_InitStructure);
	//GPIO_WriteBit(GPIOA, GPIO_Pin_7,Bit_SET); // PA7上拉	

	TIM_TimeBaseStructure.TIM_Period = arr; //设置在下一个更新事件装入活动的自动重装载寄存器周期的值	 80K
	TIM_TimeBaseStructure.TIM_Prescaler =psc; //设置用来作为TIMx时钟频率除数的预分频值  不分频
	TIM_TimeBaseStructure.TIM_ClockDivision = 0; //设置时钟分割:TDTS = Tck_tim
	TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;  //TIM向上计数模式
	TIM_TimeBaseInit(TIM3, &TIM_TimeBaseStructure); //根据TIM_TimeBaseInitStruct中指定的参数初始化TIMx的时间基数单位
	
	 
	TIM_OCInitStructure.TIM_OCMode = TIM_OCMode_PWM2; //选择定时器模式:TIM脉冲宽度调制模式2
	TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable; //比较输出使能
	TIM_OCInitStructure.TIM_Pulse = 0; //设置待装入捕获比较寄存器的脉冲值
	TIM_OCInitStructure.TIM_OCPolarity = TIM_OCPolarity_High; //输出极性:TIM输出比较极性高
	TIM_OC2Init(TIM3, &TIM_OCInitStructure);  //根据TIM_OCInitStruct中指定的参数初始化外设TIMx
	TIM_OC2PreloadConfig(TIM3, TIM_OCPreload_Enable);  //使能TIMx在CCR2上的预装载寄存器
	
	TIM_ARRPreloadConfig(TIM3, ENABLE); //使能TIMx在ARR上的预装载寄存器
	
 
	TIM_Cmd(TIM3, ENABLE);  //使能TIMx外设
 

}
