TIM1的步进电机驱动问题

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STM32中的高级定时器TIM1可作为专门的电机驱动定时器。通过设置TIM1_CCER寄存器的CCxE、CCxNE位。

	A	B	C	D
	CH1	CH1N	CH2	CH2N	CC1E/CC1EN	CC2E/CC2EN	TIM1_CCER Step[N]
1	PWM	-	PWM	-	10	10	0x0011
2	PWM	-	-	PWM	10	01	0x0041
3	-	PWM	-	PWM	01	01	0x0044
4	-	PWM	PWM	-	01	10	0x0014

CCER_MASK = 0x0055
TIM1_CCER &= ~ CCER_MASK;
TIM1_CCER |= Step[N], N=0,1,2,3


TIM1时钟FTIM1_CLK = 72M/72=1MHz。ARR值（Period）为400。
则：PWM周期TPWM = 1us × 400 ＝ 400us
CCR1、CCR2值为100。则占空比τ＝100/400。

TIM1初始化如下：
void TIM1_Configuration(void)
{

u16 tempCR2;



TIM_TimeBaseInitTypeDef  TIM_TimeBaseStructure;

TIM_OCInitTypeDef TIM_OCInitStructure;

TIM_BDTRInitTypeDef TIM_BDTRInitStructure;


TIM_DeInit(TIM1);



/* Time base configuration - 2.5KHz Period */

//F(CK_CNT) = 72M/(1+TIM_Prescaler )=1MHz

//TIM_Period = 1uS*400=400uS
    /* PWM输出模式*/
    /*A-PA8(TIM1_CH1), B-PA9(TIM1_CH2), C-PB13(TIM1_CH1N), D-PB14(TIM1_CH2N) */


TIM_TimeBaseStructure.TIM_Period = 400-1;

  //TIMx_ARR  

TIM_TimeBaseStructure.TIM_Prescaler = 71;

  //TIMx_PSC



TIM_TimeBaseStructure.TIM_ClockDivision = 0;






TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;   

TIM_TimeBaseInit(TIM1, &TIM_TimeBaseStructure);

TIM_ARRPreloadConfig(TIM1, ENABLE);

TIM_CCPreloadControl(TIM1, ENABLE);
//CR2寄存器的CCPC置1

tempCR2 = TIM1->CR2;

tempCR2 |= 0x0004;
//bit CCUS of CR2 Register set 1

TIM1->CR2 = tempCR2;



TIM_OCInitStructure.TIM_OCMode = TIM_OCMode_PWM2;

TIM_OCInitStructure.TIM_Pulse = CCR1_VAL;

TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable;

TIM_OCInitStructure.TIM_OutputNState = TIM_OutputNState_Enable;

TIM_OCInitStructure.TIM_OCPolarity = TIM_OCPolarity_Low;

TIM_OCInitStructure.TIM_OCNPolarity = TIM_OCNPolarity_Low;

TIM_OCInitStructure.TIM_OCIdleState = TIM_OCIdleState_Set;

TIM_OCInitStructure.TIM_OCNIdleState = TIM_OCNIdleState_Set;

TIM_OC1Init(TIM1, &TIM_OCInitStructure);

TIM_OC1PreloadConfig(TIM1, TIM_OCPreload_Disable);



TIM_OCInitStructure.TIM_Pulse = CCR1_VAL;

TIM_OC2Init(TIM1, &TIM_OCInitStructure);

TIM_OC2PreloadConfig(TIM1, TIM_OCPreload_Disable);


/* 配置自动输出允许、中止、死区和锁定级别 */

TIM_BDTRInitStructure.TIM_OSSRState = TIM_OSSRState_Enable;

TIM_BDTRInitStructure.TIM_OSSIState = TIM_OSSIState_Enable;

TIM_BDTRInitStructure.TIM_LOCKLevel = TIM_LOCKLevel_OFF;

TIM_BDTRInitStructure.TIM_DeadTime = 0;

TIM_BDTRInitStructure.TIM_Break = TIM_Break_Disable;

TIM_BDTRInitStructure.TIM_AutomaticOutput = TIM_AutomaticOutput_Disable;

TIM_BDTRConfig(TIM1, &TIM_BDTRInitStructure);


TIM1->EGR = 0x0020;
//COM置1


/* TIM IT enable [使能TIM1更新中断]*/

//TIM_ITConfig(TIM1, TIM_IT_Update, ENABLE);


TIM_ITConfig(TIM1, TIM_IT_CC1, ENABLE);


TIM_ITConfig(TIM1, TIM_IT_COM, ENABLE);




TIM_Cmd(TIM1, ENABLE);




/* MOE置1 - 主输出允许  */

TIM_CtrlPWMOutputs(TIM1, ENABLE);


}

在比较中断服务程序中调整TIM1_CCER寄存器的CCxE、CCxNE位。

#define CCER_MASK  0x00FF

const unsigned int StepperValue[4] =
{

0x0011, 0x0041, 0x0044, 0x0014
};

void TIM1_CC_IRQHandler(void)
{

u16 tmpccer = 0;



if ((TIM1->SR & 0x0002) != 0)

{


TIM1->SR &= ~(1<<1);
// clear UIF flag



TIM_CtrlPWMOutputs(TIM1, DISABLE);





/* Get the TIMx CCER register value */


tmpccer = TIM1->CCER;



tmpccer &= ~CCER_MASK;





StepMotor_Step_Num ++;


if(StepMotor_Step_Num == 4) StepMotor_Step_Num = 0;



tmpccer |= StepperValue[StepMotor_Step_Num];





/* Write to TIMx CCER */


TIM1->CCER = tmpccer;



TIM_CtrlPWMOutputs(TIM1, ENABLE);


}
}

然而，问题出在比较中断后输出波形有一小段抖动，而且PB14输出极性也产生变化。如下图所示：

图片2.jpg

期望的波形如下：

图片3.jpg

void TIM1_CC_IRQHandler(void)
{
u16 tmpccer = 0;
if ((TIM1->SR & 0x0001) != 0)
。。
}
在更新UIF标记中进行操作。软件仿真波形如下：
[img][/img]

但是在烧录到芯片后，PA8/PA9/PB13/PB14都为低电平，为什么？

波形没有插入，重新插入波形：

看不明白也要顶一把