1.定时器
(1)在RCC初始化函数中设置定时器时钟使能:
/* TIM2 clock enable */
RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM2 , ENABLE);
(2)设置定时器中断向量:
/* Configure one bit for preemption priority */
NVIC_PriorityGroupConfig(NVIC_PriorityGroup_1);
/* Enable the TIM2 Interrupt */
NVIC_InitStructure.NVIC_IRQChannel = TIM2_IRQChannel;
NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 0;//该参数设置了成员NVIC_IRQChannel中的先占优先级
NVIC_InitStructure.NVIC_IRQChannelSubPriority = 0; //该参数设置了成员NVIC_IRQChannel中的从优先级 NVIC_PriorityGroup_0,则参数NVIC_IRQChannelPreemptionPriority对中断通道的设置不产生影响。
NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;//该参数指定了在成员NVIC_IRQChannel中定义的IRQ通道被使能还是失能。这个参数取值为ENABLE或者DISABLE。
NVIC_Init(&NVIC_InitStructure);//把NVIC_InitStruct初始化
(3)初始化定时器并使能:
TIM_DeInit(TIM2);//复位TIM2定时器
TIM_TimeBaseStructure.TIM_Period = 20000; //计数值20000
TIM_TimeBaseStructure.TIM_Prescaler = 719;//(72M/(1+TIM_Prescaler ))/(1+TIM_Period ) = 频率
TIM_TimeBaseStructure.TIM_ClockDivision = 0x0; // 时钟分割
TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up; //计数方向向上计数
TIM_TimeBaseInit(TIM2, &TIM_TimeBaseStructure);
TIM_ClearFlag(TIM2, TIM_FLAG_Update);
TIM_ITConfig(TIM2, TIM_IT_Update, ENABLE);
TIM_Cmd(TIM2, ENABLE);
这里无非就是时钟分频,设置计数模式,设置时钟更行,计时值,然后交给初始化函数。
(4)在定时器中断函数里检查中断状态,清楚标志位,然后在里面做我们想做的事情:
void TIM2_IRQHandler(void)
{
if(TIM_GetITStatus(TIM2, TIM_IT_Update) != RESET)
{
TIM_ClearITPendingBit(TIM2, TIM_IT_Update);
}
}
2.PWM
pwm控制也是使用time,只不过它不再使用中断函数而且发生中断后自动设置
对应的端口电平,所以只需要配置好就好了,记得打开时钟中断的时钟.
(1)设置端口:
//TIM1完全重映射管脚
GPIO_PinRemapConfig(GPIO_FullRemap_TIM1, ENABLE);
/* Configure motor control TIM1_CH2 (PE.11)as output push-pull */
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_11;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP;
GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
GPIO_Init(GPIOE, &GPIO_InitStructure);
即重映射时钟功能,像平时一样设置对应管脚。
(2)初始化时钟:
/* Time base configuration */
TIM_TimeBaseStructure.TIM_Period = 1999;
TIM_TimeBaseStructure.TIM_Prescaler =720-1/*720/8-1*/;
TIM_TimeBaseStructure.TIM_ClockDivision = TIM_CKD_DIV1;//0
TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;
TIM_TimeBaseInit(TIM3, &TIM_TimeBaseStructure);
//==启用ARR的影子寄存器(直到产生更新事件才更改设置)
TIM_ARRPreloadConfig(TIM3, ENABLE);
/* PWM1 Mode configuration: Channel1 */
TIM_OCInitStructure.TIM_OCMode = TIM_OCMode_PWM1;//60
TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable;//配置为互补输出
TIM_OCInitStructure.TIM_OutputNState = TIM_OutputNState_Enable;
TIM_OCInitStructure.TIM_OCPolarity = TIM_OCPolarity_High;
TIM_OCInitStructure.TIM_OCNPolarity = TIM_OCNPolarity_High;
TIM_OCInitStructure.TIM_Pulse = CCR_Val_steer;//150
TIM_OC1Init(TIM3, &TIM_OCInitStructure);
//==启用CCR1寄存器的影子寄存器(直到产生更新事件才更改设置)
TIM_OC1PreloadConfig(TIM3, TIM_OCPreload_Enable);
/* TIM3 enable counter */
TIM_Cmd(TIM3, ENABLE);
/*=== TIM3_OC通道输出PWM ===*/
TIM_CtrlPWMOutputs(TIM3, ENABLE);
这里设置时钟分频,计数值及比较值及启动影子寄存器等,以上的只要修改很少的参数就可
重复使用。