这个暑假没有回家，在学校准备九月份的电子设计竞赛。今天想给大家分享一下STM32高级定时器输出PWM波驱动直流电机的问题。。
要想用定时器输出的PWM控制直流电机，，首先要理解“通道”的概念。。一个定时器可以支持一个PWM，要支持多个，就需要各路PWM周期相同而占空比不同。。利用定时器的通道这一概念就可以实现。STM32单片机定时器有四个通道，每个通道的TIM1——CCRx（x=1、2、3、4）存放一个值。。计数器从0开始计数，此时PWM输出为0。。当计数值达到寄存值时，此时PWM电平发生翻转，输出1。。所以设置四个不同的占空比的值，就可以产生四路PWM波。
本例程使用高级定时器TIM1输出两路PWM波分别控制左边两个轮子轮和右边两个轮子。TIM1时钟频率是72MHz，如果要输出20KHz的PWM波，，应该把TIM1_Period设为3600-1。具体代码如下所示：
void TIM_Configuration(vu16 CCR1,vu16 CCR2)
{
TIM1_TimeBaseInitTypeDef TIM1_TimeBaseStructure;
TIM1_OCInitTypeDef TIM1_OCInitStructure;
TIM1_CtrlPWMOutputs(DISABLE);
/* TIM1 Peripheral Configuration */
TIM1_DeInit();
/* Time Base configuration */
TIM1_TimeBaseStructure.TIM1_Prescaler = 0;
TIM1_TimeBaseStructure.TIM1_CounterMode = TIM1_CounterMode_Up;
TIM1_TimeBaseStructure.TIM1_Period = 3599;
TIM1_TimeBaseStructure.TIM1_ClockDivision = 0;
TIM1_TimeBaseStructure.TIM1_RepetitionCounter = 0;
TIM1_TimeBaseInit(&TIM1_TimeBaseStructure);
/* Channel 1, 2,3 and 4 Configuration in PWM mode */
TIM1_OCInitStructure.TIM1_OCMode = TIM1_OCMode_PWM2;
TIM1_OCInitStructure.TIM1_OutputState = TIM1_OutputState_Enable;
TIM1_OCInitStructure.TIM1_OutputNState = TIM1_OutputNState_Enable;
TIM1_OCInitStructure.TIM1_Pulse = CCR1;
TIM1_OCInitStructure.TIM1_OCPolarity = TIM1_OCPolarity_Low;
TIM1_OCInitStructure.TIM1_OCNPolarity = TIM1_OCNPolarity_Low;
TIM1_OCInitStructure.TIM1_OCIdleState = TIM1_OCIdleState_Set;
TIM1_OCInitStructure.TIM1_OCNIdleState = TIM1_OCIdleState_Reset;
TIM1_OC1Init(&TIM1_OCInitStructure);
TIM1_OCInitStructure.TIM1_Pulse = CCR2;
TIM1_OC2Init(&TIM1_OCInitStructure);
/* TIM1 counter enable */
TIM1_Cmd(ENABLE);
/* Main Output Enable */
TIM1_CtrlPWMOutputs(ENABLE);
}
最后可以调用这个函数实现小车的前进，后退，左转，右转。。好的，，今天就写到这里，希望地大家有用。。