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本帖最后由 yick 于 2015-8-14 13:55 编辑
大致情况是,
①我用TIM2 设置频率为50HZ arr = 19999,psc = 71作为舵机的频率,
那么设置占空比为5%-10%舵机正常运转。
②这时加入串口,用的定时器4,arr = 99, psc =7199,
这个时候舵机就开始发抖,大致情况就相当于我最开始设置TIM2 arr = 199, psc = 7199这种情况
我用示波器量过,在①这种情况,频率比较稳定;在②这种情况,频率跳动很大,感觉就是频率在干扰。
请问这是为什么?是我没有NVIC搞的频率乱掉了,还是?求解。
下面贴上我的两个TIM配置代码:
舵机(TIM2)
- void TIM2_PWM_SERVO_Init(u16 arr,u16 psc)//19999,71
- {
- GPIO_InitTypeDef GPIO_InitStructure;
- TIM_TimeBaseInitTypeDef TIM_TimeBaseStructure;
- TIM_OCInitTypeDef TIM_OCInitStructure;
- // NVIC_InitTypeDef NVIC_InitStructure;
-
- RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM2, ENABLE); //使能定时器2时钟
- RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA | RCC_APB2Periph_AFIO, ENABLE); //使能GPIO外设和AFIO复用功能模块时钟
- //GPIO_PinRemapConfig(GPIO_FullRemap_TIM2, ENABLE); //Timer2部分重映射 TIM3_CH2->PB5
-
- /*控制舵(电)机的IO口模式配置*/
- GPIO_InitStructure.GPIO_Pin = GPIO_Pin_1; //TIM_CH1,TIM_CH2
- GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP; //复用推挽输出 GPIO_Mode_Out_PP
- GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
- GPIO_Init(GPIOA, &GPIO_InitStructure); //初始化GPIO
- /*初始化TIM2*/
- TIM_TimeBaseStructure.TIM_Period = arr; //自动重装载寄存器周期的值(计数值) 单位US, arr
- TIM_TimeBaseStructure.TIM_Prescaler = psc; // 时钟预分频数 72M/72=1MHZ 1/1M=1us psc
- TIM_TimeBaseStructure.TIM_ClockDivision = 0; //设置时钟分割:TDTS = Tck_tim,采样分频
- TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up; //TIM向上计数模式
- TIM_TimeBaseInit(TIM2, &TIM_TimeBaseStructure); //根据TIM_TimeBaseInitStruct中指定的参数初始化TIMx的时间基数单位
-
- /* PWM2 Mode configuration: Channel2 */
- TIM_OCInitStructure.TIM_OCMode = TIM_OCMode_PWM2; //配置为PWM模式2
- TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable; //比较输出使能
- TIM_OCInitStructure.TIM_Pulse = 0; //设置跳变值,当计数器计数到这个值时,电平发生跳变
- TIM_OCInitStructure.TIM_OCPolarity = TIM_OCPolarity_Low; //当定时器计数值小于CCR1_Val时为高电平
-
- /*通道2的选择,对应前轮*/
- TIM_OC2Init(TIM2, &TIM_OCInitStructure); //使能通道2
- TIM_OC2PreloadConfig(TIM2, TIM_OCPreload_Enable); //使能TIMx在CCR2上的预装载寄存器
-
- TIM_ARRPreloadConfig(TIM2, ENABLE); //使能TIMx在ARR上的预装载寄存器
- TIM_Cmd(TIM2, ENABLE); //使能TIM2
-
- }
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串口定时器配置(TIM4)
- void UART4_Init(u32 bound)
- {
- //GPIO端口设置
- GPIO_InitTypeDef GPIO_InitStructure;
- NVIC_InitTypeDef NVIC_InitStructure;
- USART_InitTypeDef UART_InitStructure;
-
- RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOC|RCC_APB2Periph_AFIO ,ENABLE); // GPIOC时钟
- RCC_APB1PeriphClockCmd(RCC_APB1Periph_UART4,ENABLE);
-
- USART_DeInit(UART4); //复位串口4
-
- //UART4_TX PC.10
- GPIO_InitStructure.GPIO_Pin = GPIO_Pin_10; //PC.10
- GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
- GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP; //复用推挽输出
- GPIO_Init(GPIOC, &GPIO_InitStructure); //初始化PC.10
- //UART4_RX PC.11
- GPIO_InitStructure.GPIO_Pin = GPIO_Pin_11;//PC.11
- GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IN_FLOATING;//浮空输入
- GPIO_Init(GPIOC, &GPIO_InitStructure); //初始化PC.11
-
- UART_InitStructure.USART_BaudRate = bound;//一般设置为9600;
- UART_InitStructure.USART_WordLength = USART_WordLength_8b;//字长为8位数据格式
- UART_InitStructure.USART_StopBits = USART_StopBits_1;//一个停止位
- UART_InitStructure.USART_Parity = USART_Parity_No;//无奇偶校验位
- UART_InitStructure.USART_HardwareFlowControl = USART_HardwareFlowControl_None;//无硬件数据流控制
- UART_InitStructure.USART_Mode = USART_Mode_Rx | USART_Mode_Tx; //收发模式
-
- USART_Init(UART4, &UART_InitStructure); //初始化串口 4
- UART_DMA_Config(DMA2_Channel5,(u32)&UART4->DR,(u32)UART4_TX_BUF);//DMA2通道5,外设为串口2,存储器为USART2_TX_BUF
- USART_Cmd(UART4, ENABLE); //使能串口
-
- USART_ITConfig(UART4, USART_IT_RXNE, ENABLE);//开启中断
- NVIC_InitStructure.NVIC_IRQChannel = UART4_IRQn;
- NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority=2 ;//抢占优先级3
- NVIC_InitStructure.NVIC_IRQChannelSubPriority = 3; //子优先级3
- NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE; //IRQ通道使能
- NVIC_Init(&NVIC_InitStructure); //根据指定的参数初始化VIC寄存器
-
- TIM4_Init(99,7199); //10ms中断 99,7199
- UART4_RX_STA=0; //清零
- TIM4_Set(0); //关闭定时器4
- }
- void TIM4_Init(u16 arr,u16 psc)
- {
- NVIC_InitTypeDef NVIC_InitStructure;
- TIM_TimeBaseInitTypeDef TIM_TimeBaseStructure;
- RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM4, ENABLE); //时钟使能//TIM4时钟使能
-
- //定时器TIM4初始化
- TIM_TimeBaseStructure.TIM_Period = arr; //设置在下一个更新事件装入活动的自动重装载寄存器周期的值
- TIM_TimeBaseStructure.TIM_Prescaler =psc; //设置用来作为TIMx时钟频率除数的预分频值
- TIM_TimeBaseStructure.TIM_ClockDivision = TIM_CKD_DIV1; //设置时钟分割:TDTS = Tck_tim
- TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up; //TIM向上计数模式
- TIM_TimeBaseInit(TIM4, &TIM_TimeBaseStructure); //根据指定的参数初始化TIMx的时间基数单位
-
- TIM_ITConfig(TIM4,TIM_IT_Update,ENABLE ); //使能指定的TIM4中断,允许更新中断
-
- NVIC_InitStructure.NVIC_IRQChannel = TIM4_IRQn;
- NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority=1 ;//抢占优先级3
- NVIC_InitStructure.NVIC_IRQChannelSubPriority = 2; //子优先级3
- NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE; //IRQ通道使能
- NVIC_Init(&NVIC_InitStructure); //根据指定的参数初始化VIC寄存器
-
- }
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