TIM8+DMA2的通道3输出1MHZ的PWM，波形有问题

CKJJJJ · 发表于 2020-3-30 14:18:27

本帖最后由 CKJJJJ 于 2020-3-30 14:47 编辑

参照一个大佬的代码，改自己想要的效果。只要频率调大了，波形就有问题。占空比明明设置了固定，但占空比却会变化，最终波形没了，只剩高电平（第二个图是第一个图的放大图）

#define PWM_TIMx                      TIM8
#define PWM_TIM_APBxClock_CMD          RCC_APB2PeriphClockCmd
#define PWM_TIM_CLK                   RCC_APB2Periph_TIM8
#define PWM_TIM_GPIO_CLK                (RCC_APB2Periph_GPIOC | RCC_APB2Periph_AFIO )

void TIM_Dma_Pwm_Pulse_Output_Init(u16 arr,u16 psc)
{
GPIO_InitTypeDef       GPIO_InitStructure;
TIM_TimeBaseInitTypeDef  TIM_TimeBaseStructure;
TIM_OCInitTypeDef       TIM_OCInitStructure;
DMA_InitTypeDef       DMA_InitStructure;
NVIC_InitTypeDef       NVIC_InitStructure;

TIM_TimeBaseStructInit(&TIM_TimeBaseStructure);                //设置缺省值,这一步最好加上防止放到串口初始化后出问题
TIM_OCStructInit(&TIM_OCInitStructure);                         //设置缺省值,这一步最好加上防止放到串口初始化后出问题
//TIM_ICStructInit(&TIM_ICInitStructure);                      //设置缺省值,这一步最好加上防止放到串口初始化后出问题

PWM_TIM_APBxClock_CMD(PWM_TIM_CLK, ENABLE);                               //使能定时器时钟
PWM_TIM_GPIO_APBxClock_CMD(PWM_TIM_GPIO_CLK, ENABLE);       //使能GPIO外设和AFIO复用功能模块时钟
RCC_AHBPeriphClockCmd(RCC_AHBPeriph_DMA2, ENABLE);

GPIO_InitStructure.GPIO_Pin = GPIO_Pin_6;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP;
GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
GPIO_Init(GPIOC, &GPIO_InitStructure);

//初始化TIM
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(PWM_TIMx, &TIM_TimeBaseStructure);

//初始化TIM3 Channe1 PWM模式
TIM_OCInitStructure.TIM_OCMode = TIM_OCMode_PWM1;                   //选择定时器模式:TIM脉冲宽度调制模式2
TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable;       //比较输出使能
TIM_OCInitStructure.TIM_OCPolarity = TIM_OCPolarity_High;          //输出极性:TIM输出比较极性高
TIM_OCInitStructure.TIM_OCIdleState = TIM_OCIdleState_Set;
TIM_OCInitStructure.TIM_OCNIdleState = TIM_OCIdleState_Reset;
TIM_OC1Init(PWM_TIMx, &TIM_OCInitStructure);                   //初始化通道1
TIM_OC1PreloadConfig(PWM_TIMx, TIM_OCPreload_Enable);          //使能TIM在通道1上的预装载寄存器

/*******DMA2_CH3  ---- TIM8_CH1 *********/
DMA_DeInit(DMA2_Channel3);                                              //将DMA的通道1寄存器重设为缺省值
DMA_InitStructure.DMA_PeripheralBaseAddr = (u32)&PWM_TIMx->CCR1;          //DMA外设基地址
DMA_InitStructure.DMA_MemoryBaseAddr    = (u32)&Duty1;                                              //DMA内存基地址
DMA_InitStructure.DMA_DIR             = DMA_DIR_PeripheralDST;       //DMA_DIR_PeripheralSRC:从外设读  DMA_DIR_PeripheralDST:从内存读
DMA_InitStructure.DMA_BufferSize       = 0;                            //DMA通道的DMA缓存的大小，实测不加1少一个，应该是最后一个还没输出就中断关闭定时器了，+1就好了
DMA_InitStructure.DMA_PeripheralInc    = DMA_PeripheralInc_Disable;    //外设地址寄存器不变
DMA_InitStructure.DMA_MemoryInc       = DMA_MemoryInc_Disable;                   //内存地址寄存器递增
DMA_InitStructure.DMA_PeripheralDataSize = DMA_PeripheralDataSize_HalfWord;//数据宽度为8位
DMA_InitStructure.DMA_MemoryDataSize    = DMA_MemoryDataSize_HalfWord; //数据宽度为8位
DMA_InitStructure.DMA_Mode             = DMA_Mode_Normal;             //工作在正常模式
DMA_InitStructure.DMA_Priority          = DMA_Priority_High;          //DMA通道 x拥有中优先级
DMA_InitStructure.DMA_M2M             = DMA_M2M_Disable;
DMA_Init(DMA2_Channel3, &DMA_InitStructure);                            //根据DMA_InitStruct中指定的参数初始化DMA的通道所标识的寄存器
DMA_Cmd(DMA2_Channel3, ENABLE);                                           //DMA使能

TIM_DMACmd(PWM_TIMx,TIM_DMA_CC1, ENABLE);

NVIC_PriorityGroupConfig(NVIC_PriorityGroup_2);
NVIC_InitStructure.NVIC_IRQChannel = DMA2_Channel3_IRQn;
NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 2;
NVIC_InitStructure.NVIC_IRQChannelSubPriority = 0x02;
NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
NVIC_Init(&NVIC_InitStructure);
DMA_ClearFlag(DMA2_Channel3_IRQn);                                        //清除DMA所有标志
DMA_ITConfig(DMA2_Channel3,DMA_IT_TC,ENABLE);                            //开传输完成中断

TIM_SetCompare1(PWM_TIMx,0);    //通道1
TIM_CtrlPWMOutputs(PWM_TIMx, ENABLE);//高级定时器用
TIM_Cmd(PWM_TIMx, ENABLE);       //使能TIM

void TIM_Dma_Pwm_Pulse_Output1(u8 Duty,u16 Pls_Num)
{
      //TIM_Cmd(PWM_TIMx, DISABLE);
      Duty1=(PWM_TIMx->ARR+1)*Duty/100;                                  //计算占空比
TIM_SetCompare1(PWM_TIMx,Duty1);                      //占空比填入比较寄存器

DMA_Cmd(DMA2_Channel3, DISABLE);                      //DMA失能才能设置
DMA_SetCurrDataCounter(DMA2_Channel3,Pls_Num+1);       //设置DMA长度，即脉冲数量
DMA_Cmd(DMA2_Channel3, ENABLE);                      //开启
//TIM_Cmd(PWM_TIMx, ENABLE);
}

void DMA2_Channel3_IRQHandler(void)                                                       //脉冲输出完毕，关闭输出
{
if(DMA_GetITStatus(DMA2_FLAG_TC3))
{
      TIM_SetCompare1(PWM_TIMx, 0);
      DMA_ClearFlag(DMA2_Channel3_IRQn);
      DMA_ClearFlag(DMA2_FLAG_GL3);
}
}

主函数main
TIM_Dma_Pwm_Pulse_Output_Init(2-1,72-1);//硬件初始化默认周期=2*72/72000000=2us
      while(1)
      {
            TIM_Dma_Pwm_Pulse_Output1(50, 1000);
            delay_ms(5);
}

nashui_sx · 发表于 2020-3-30 14:18:28

本帖最后由 nashui_sx 于 2020-3-30 16:03 编辑

你还没搞定呀我给你改的定时器1的代码肯定可以 TIM_Dma_Pwm_Pulse_Output_Init(2-1,72-1);---->TIM_Dma_Pwm_Pulse_Output_Init(12-1,12-1);试试，你那就计数两个数还没开始就结束了，中断都反应不过来
你都不听我的，让你先低频逐步高频，看到啥时候出问题后面72-1 前面到4基本就会有问题不稳定，那就是计数太小了后面变小前面变大
QQ截图20200330143513.png