STM32f103ZET6 drives a 42-step motor

STM32f103ZET6 Using PWM output and timer interrupt to control the stepper motor rotation fixed number of laps problem

Specific configuration:
TB6600 stepper motor driver, dip is subdivided into 200 pulse turn a circle;
Stepper motor is 42 stepper motor;
SCM PWM output pin PA0, PC13 to control the positive and negative rotation
timer uses TIM5, channel TIM5_CH1;

This is the timer and PWM configuration:

void TIM5_Init(u16 arr,u16 psc)
{ 
    GPIO_InitTypeDef GPIO_InitStructure;
    TIM_TimeBaseInitTypeDef TIM_TimeBaseStructure;
    TIM_OCInitTypeDef  TIM_OCInitStructure;
    
//1、使能时钟，此处使用的是TIM5，相关引脚为PA0：TIM5_CH1
    RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM5,ENABLE);
    RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA,ENABLE);
    
//2、设置GPIO口为复用功能
    GPIO_InitStructure.GPIO_Pin = GPIO_Pin_0;
    GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
    GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP;
    GPIO_Init(GPIOA,&GPIO_InitStructure);

//3、初始化定时器TIM5
    TIM_TimeBaseStructure.TIM_Period = arr;
    TIM_TimeBaseStructure.TIM_Prescaler = psc;
    TIM_TimeBaseStructure.TIM_ClockDivision = 0;
    TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;
    TIM_TimeBaseInit(TIM5,&TIM_TimeBaseStructure);


//4、初始化PWM
    TIM_OCInitStructure.TIM_OCMode = TIM_OCMode_PWM2; 
    TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable; 
    TIM_OCInitStructure.TIM_OCPolarity = TIM_OCPolarity_High; 
    TIM_OC1Init(TIM5, &TIM_OCInitStructure);
    
//5、使能PWM的预装载和重装载功能
    TIM_OC1PreloadConfig(TIM5, TIM_OCPreload_Enable);
    TIM_ARRPreloadConfig(TIM5,ENABLE);
    
//6、启动定时器
    TIM_ITConfig(TIM5, TIM_IT_Update, ENABLE);
    TIM_Cmd(TIM5,ENABLE);
    

}

This is the timer interrupt handler

void TIM5_IRQHandler(void)
{
    static int count = 1;
    if (TIM_GetITStatus(TIM5, TIM_IT_Update) != RESET) 
    {
        TIM_ClearITPendingBit(TIM5, TIM_IT_Update);  
        u1_printf("%d  ",count);

        count++;
        if(count == 200){             
            TIM_Cmd(TIM5,DISABLE);
        }
    }
}

This is the main function

int main()
{
    //使用的PC13来控制步进电机正反转
    PCout(13) = 1;

    //计数值为99+1，周期为719+1
    TIM5_Init(99,719);

    //设置占空比50%
    TIM_SetCompare1(TIM5,50); 
    NVIC_Config();
    
}

Supposedly, 200 pulses rotate once, but in fact, the motor rotates many times. I really can't find the problem, please give me some advice, thank you!