stm32定时器输出固定频率10kHZ，固定占空比，用示波器观察，为什么会出现占空比有飘动的现象？

战隼

[mw_shl_code=c,true]void TIM1_PWM_Init(u16 arr,u16 psc) { GPIO_InitTypeDef GPIO_InitStructure; TIM_TimeBaseInitTypeDef TIM_TimeBaseStructure; TIM_OCInitTypeDef TIM_OCInitStructure; RCC_APB2PeriphClockCmd(RCC_APB2Periph_AFIO, ENABLE); RCC_APB2PeriphClockCmd(RCC_APB2Periph_TIM1, ENABLE); RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA, ENABLE); GPIO_InitStructure.GPIO_Pin = GPIO_Pin_10 | GPIO_Pin_11 ; GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz; GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP; //复用满负载输出为3.3V GPIO_Init(GPIOA, &GPIO_InitStructure); TIM_TimeBaseStructure.TIM_Prescaler = psc; TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up; TIM_TimeBaseStructure.TIM_Period = arr; TIM_TimeBaseStructure.TIM_ClockDivision = 0; TIM_TimeBaseStructure.TIM_RepetitionCounter = 0; TIM_TimeBaseInit(TIM1, &TIM_TimeBaseStructure); TIM_OCInitStructure.TIM_OCMode = TIM_OCMode_PWM2; TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable; TIM_OCInitStructure.TIM_OutputNState = TIM_OutputNState_Disable; TIM_OCInitStructure.TIM_OCPolarity = TIM_OCPolarity_Low; TIM_OCInitStructure.TIM_OCNPolarity = TIM_OCNPolarity_High; TIM_OCInitStructure.TIM_OCIdleState = TIM_OCIdleState_Set; TIM_OCInitStructure.TIM_OCNIdleState = TIM_OCIdleState_Reset; TIM_OC3Init(TIM1, &TIM_OCInitStructure); TIM_OC4Init(TIM1, &TIM_OCInitStructure); TIM1->CCR3 = 0; //PA10 上理论能输出0.33V电压 误差0.1V TIM1->CCR4 = 0; //PA9 上理论能输出0.66V电压 误差0.1V TIM_Cmd(TIM1, ENABLE); TIM_CtrlPWMOutputs(TIM1, ENABLE); }[/mw_shl_code]

xuande

1、如果重新启动过定时器，要对 CNT 寄存器清零。

2、示波器问题？

战隼

回复【2楼】xuande:
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1.没有重新启动
2，换了个示波器，依然有跳动。
3刷了原子定时器产生固定pwm的程序，只是改了频率（10M）和占空比,但是显示还有跳动
3.换了一块开发板，还有跳动
4.频率改为100hz,占空比保持不变。显示无跳动。正常
（跳动范围：本来应该输出55%稳定的占空比，但是示波器上有时显示55%，有时显示57%。)

这是什么问题呢？

烟酒不沾

调节一下示波器的触发电平看看！