设置定时器的pwm输出时需配置TIM_OCInitTypeDef结构体的参数，输入捕获是用TIM_ICInitTypeDef结构体。
typedef struct
{
uint16_t TIM_OCMode; //
uint16_t TIM_OutputState; //输出状态
uint16_t TIM_OutputNState; //互补通道的输出状态
uint16_t TIM_Pulse; //占空比
uint16_t TIM_OCPolarity; //输出极性
uint16_t TIM_OCNPolarity; //互补通道的输出极性
uint16_t TIM_OCIdleState; //空闲状态
uint16_t TIM_OCNIdleState; //互补通道的空闲状态
} TIM_OCInitTypeDef;
互补通道的参数都有，如果像只用一个通道比如用的T15_CH1N,则配置带N的参数，注意参数值也要选带N的，TIM_OCPolarity_Low和TIM_OCNPolarity_Low值是不一样的，不能混用，因为对应寄存器的控制位不一样。
TIM_OCInitStructure.TIM_OCMode = TIM_OCMode_PWM1; //TIM脉冲宽度调制模式1
TIM_OCInitStructure.TIM_OutputNState = TIM_OutputNState_Enable; //比较输出使能
TIM_OCInitStructure.TIM_OCNPolarity = TIM_OCNPolarity_Low; //输出极性:TIM输出比较极性低
TIM_OCInitStructure.TIM_OCNIdleState = TIM_OCNIdleState_Reset;//输出空闲状态
TIM_OCInitStructure.TIM_Pulse =ChannelPulse; //占空比
TIM_OC1Init(TIM15, &TIM_OCInitStructure);
比如T3_CH2:
TIM_OCInitStructure.TIM_OCMode = TIM_OCMode_PWM2; //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_OCPolarity = TIM_OCPolarity_High; //输出极性:TIM输出比较极性高
TIM_OCInitStructure.TIM_OCIdleState = TIM_OCIdleState_Reset; //空闲状态，低电平
TIM_OCInitStructure.TIM_Pulse = ChannelPulse;//占空比
TIM_OC2Init(TIM3, &TIM_OCInitStructure);
TIM_OCInitStructure的参数配置不涉及通道，通道的选择就是靠TIM_OCxInit区分。
先看第一个参数：TIM_OCMode对应寄存器CCMR1的6：4位:
主要看TIM_OCMode_PWM1 和 TIM_OCMode_PWM2的区别
#define TIM_OCMode_PWM1 ((uint16_t)0x0060)即6：4=110
#define TIM_OCMode_PWM2 ((uint16_t)0x0070) 即6：4=111
那谁是有效电平呢？看寄存器CCER
对应这两句：
TIM_OCInitStructure.TIM_OCPolarity = TIM_OCPolarity_High;//有效电平为高电平，即输出极性CC2P=0
TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable; //比较输出使能，即CC2E=1
还有最后一个参数：TIM_OCInitStructure.TIM_OCIdleState = TIM_OCIdleState_Reset;对应CR2的第8位：
#define TIM_OCIdleState_Set ((uint16_t)0x0100)
#define TIM_OCIdleState_Reset ((uint16_t)0x0000)
知道了定义后看看定时器3的设置会产生什么样的波形：（TIM_OCMode_PWM2，TIM_OCPolarity_High，占空比30%）
占空比30%对应的计数值ChannelPulse = (uint16_t) (((uint32_t) 30 * (周期计数值-1)) / 100);
（TIM_OCMode_PWM1，TIM_OCPolarity_High，占空比30%）
（TIM_OCMode_PWM1，TIM_OCPolarity_Low，占空比30%）
（TIM_OCMode_PWM2，TIM_OCPolarity_Low，占空比30%）
附完整的定时器初始化（stm32f072的PA1引脚对应T15_CH1N）：
/*
PA1--AF5--TIM15CH1N
**************************************************************************
*/
void TIM15_PWM_Init(void)
{
uint16_t ChannelPulse = 0,PWM_TimerPeriod;
GPIO_InitTypeDef GPIO_InitStructure;
TIM_TimeBaseInitTypeDef TIM_TimeBaseStructure;
TIM_OCInitTypeDef TIM_OCInitStructure;
NVIC_InitTypeDef NVIC_InitStructure;
//引脚初始化
RCC_APB2PeriphClockCmd(RCC_APB2Periph_TIM15 , ENABLE);
RCC_AHBPeriphClockCmd(RCC_AHBPeriph_GPIOA, ENABLE);//使能GPIOA时钟和复用功能时钟
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_1; //TIM2二通道PWM波形输出端口PA1
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF;
GPIO_InitStructure.GPIO_OType = GPIO_OType_PP;//设置引脚为推挽输出
GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_NOPULL; //设置引脚为上拉
GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz; //设置引脚速度为50MHZ
GPIO_Init(GPIOA, &GPIO_InitStructure);
GPIO_PinAFConfig(GPIOA, GPIO_PinSource1, GPIO_AF_5);
/*
系统时钟48mhz，要实现150us周期，即6.67khz，48m/6.67k=7196
48M/4800=10khz
*/
PWM_TimerPeriod = (unsigned int)( 4800 ) - 1;
ChannelPulse = (uint16_t) (((uint32_t) 95 * PWM_TimerPeriod ) / 100);//占空比5%
/* Time 定时基础设置*/
TIM_TimeBaseStructure.TIM_Prescaler = 0;
TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up; /* Time 定时设置为上升沿计算模式*/
TIM_TimeBaseStructure.TIM_Period = PWM_TimerPeriod;
TIM_TimeBaseStructure.TIM_ClockDivision = 0;
TIM_TimeBaseStructure.TIM_RepetitionCounter = 0;
TIM_TimeBaseInit(TIM15, &TIM_TimeBaseStructure);
TIM_ARRPreloadConfig(TIM15, ENABLE);
TIM_OCInitStructure.TIM_OCMode = TIM_OCMode_PWM1; //TIM脉冲宽度调制模式1
TIM_OCInitStructure.TIM_OutputNState = TIM_OutputNState_Enable; //比较输出使能
TIM_OCInitStructure.TIM_OCNPolarity = TIM_OCNPolarity_Low; //输出极性:TIM输出比较极性低
TIM_OCInitStructure.TIM_OCNIdleState = TIM_OCNIdleState_Reset;//输出空闲状态
TIM_OCInitStructure.TIM_Pulse =ChannelPulse; //设置待装入捕获比较寄存器的脉冲值,取值必须在0x0000~0xFFFF之间
TIM_OC1Init(TIM15, &TIM_OCInitStructure); //根据TIM_OCInitStruct中指定的参数初始化外设TIMx
TIM_OC1PreloadConfig(TIM15, TIM_OCPreload_Enable); //使能TIMx在CCR1上的预装载寄存器
TIM_Cmd(TIM15, ENABLE);
/* TIM1 Main Output Enable */
TIM_CtrlPWMOutputs(TIM15, ENABLE);
}stm32f103的TIM3_CH2对应引脚PB5初始化：
//arr：自动重装值
//psc：时钟预分频数
void TIM3_PWM_Init(u16 arr,u16 psc)
{
uint16_t ChannelPulse = 0;
GPIO_InitTypeDef GPIO_InitStructure;
TIM_TimeBaseInitTypeDef TIM_TimeBaseStructure;
TIM_OCInitTypeDef TIM_OCInitStructure;
RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM3, ENABLE); //使能定时器3时钟
RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOB | RCC_APB2Periph_AFIO, ENABLE); //使能GPIO外设和AFIO复用功能模块时钟
GPIO_PinRemapConfig(GPIO_PartialRemap_TIM3, ENABLE); //Timer3部分重映射 TIM3_CH2->PB5
//设置该引脚为复用输出功能,输出TIM3 CH2的PWM脉冲波形 GPIOB.5
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_5; //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(GPIOB, &GPIO_InitStructure);//初始化GPIO
ChannelPulse = (uint16_t) (((uint32_t) 30 * (arr+1)) / 100);//占空比30%
//初始化TIM3
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
TIM_TimeBaseStructure.TIM_Prescaler =psc; //设置用来作为TIMx时钟频率除数的预分频值
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_ARRPreloadConfig(TIM3, ENABLE);
//初始化TIM3 Channel2 PWM模式
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_OCPolarity = TIM_OCPolarity_High; //输出极性:TIM输出比较极性高
TIM_OCInitStructure.TIM_OCIdleState = TIM_OCIdleState_Reset;
TIM_OCInitStructure.TIM_Pulse = ChannelPulse;
TIM_OC2Init(TIM3, &TIM_OCInitStructure); //根据T指定的参数初始化外设TIM3 OC2
TIM_OC2PreloadConfig(TIM3, TIM_OCPreload_Enable); //使能TIM3在CCR2上的预装载寄存器
TIM_Cmd(TIM3, ENABLE); //使能TIM3
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