TIM_OCInitTypeDef TIM_OCInitStruct;
        TIM_OCInitStruct.TIM_OCMode=TIM_OCMode_PWM1;
        TIM_OCInitStruct.TIM_OutputState=ENABLE;
        TIM_OCInitStruct.TIM_OCPolarity=TIM_OCPolarity_High;
        TIM_OCInitStruct.TIM_Pulse=100;
        TIM_OC1Init(TIM4,&TIM_OCInitStruct);
        TIM_OC2Init(TIM4,&TIM_OCInitStruct);
        TIM_OC3Init(TIM4,&TIM_OCInitStruct);
        TIM_OC4Init(TIM4,&TIM_OCInitStruct);