STM32F407DMA无法控制PWM输出占空比是代码哪里的错误
STM32F407,利用原子哥的DMA控制串口打印输出源码，改写DMA控制PWM输出占空比，但是结果为有波形输出，无占空比变化。单独测试PWM的输出没有问题。请大家帮忙看一下是哪里的错误~自己实在找不出问题出在哪儿了http://www.openedv.com/static/image/smiley/default/handshake.gif
我利用的是TIM3的通道1，PB4引脚
下面是我对于TIM3、DMA的配置和主函数的改写代码
void TIM3_PWM_Init(u32 arr,u32 psc)
{
GPIO_InitTypeDef GPIO_InitStructure;
TIM_TimeBaseInitTypeDefTIM_TimeBaseStructure;
TIM_OCInitTypeDefTIM_OCInitStructure;
NVIC_InitTypeDef NVIC_InitStructure;
RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM3,ENABLE);
RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOB, ENABLE);
GPIO_PinAFConfig(GPIOB,GPIO_PinSource4,GPIO_AF_TIM3);
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_4; //GPIOB4
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF;
GPIO_InitStructure.GPIO_Speed = GPIO_Speed_100MHz;
GPIO_InitStructure.GPIO_OType = GPIO_OType_PP;
GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_UP;
GPIO_Init(GPIOB,&GPIO_InitStructure);
TIM_TimeBaseStructure.TIM_Prescaler=psc;
TIM_TimeBaseStructure.TIM_CounterMode=TIM_CounterMode_Up;
TIM_TimeBaseStructure.TIM_Period=arr;
TIM_TimeBaseStructure.TIM_ClockDivision=TIM_CKD_DIV1;
TIM_TimeBaseInit(TIM3,&TIM_TimeBaseStructure);
//TIM_ForcedOC1Config(TIM12, TIM_ForcedAction_InActive);
TIM_OCInitStructure.TIM_OCMode = TIM_OCMode_PWM1;
TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable;
TIM_OCInitStructure.TIM_OCPolarity = TIM_OCPolarity_High;
TIM_OC1Init(TIM3, &TIM_OCInitStructure);
TIM_OC1PreloadConfig(TIM3, TIM_OCPreload_Enable);
TIM_ARRPreloadConfig(TIM3,ENABLE);
TIM_Cmd(TIM3, ENABLE);
}
void MYDMA_Config(DMA_Stream_TypeDef *DMA_Streamx,u32 chx,u32 par,u32 mar,u16 ndtr)
{
DMA_InitTypeDefDMA_InitStructure;
if((u32)DMA_Streamx>(u32)DMA2)
{
RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_DMA2,ENABLE);
}else
{
RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_DMA1,ENABLE);
}
DMA_DeInit(DMA_Streamx);
while (DMA_GetCmdStatus(DMA_Streamx) != DISABLE){}
DMA_InitStructure.DMA_Channel = chx;
DMA_InitStructure.DMA_PeripheralBaseAddr = par;
DMA_InitStructure.DMA_Memory0BaseAddr = mar;
DMA_InitStructure.DMA_DIR = DMA_DIR_MemoryToPeripheral;
DMA_InitStructure.DMA_BufferSize = ndtr;
DMA_InitStructure.DMA_PeripheralInc = DMA_PeripheralInc_Disable;
DMA_InitStructure.DMA_MemoryInc = DMA_MemoryInc_Enable;
DMA_InitStructure.DMA_PeripheralDataSize = DMA_PeripheralDataSize_Byte;
DMA_InitStructure.DMA_MemoryDataSize = DMA_MemoryDataSize_Byte;
DMA_InitStructure.DMA_Mode = DMA_Mode_Circular;
DMA_InitStructure.DMA_Priority = DMA_Priority_Medium;
DMA_InitStructure.DMA_FIFOMode = DMA_FIFOMode_Disable;
DMA_InitStructure.DMA_FIFOThreshold = DMA_FIFOThreshold_Full;
DMA_InitStructure.DMA_MemoryBurst = DMA_MemoryBurst_Single;
DMA_InitStructure.DMA_PeripheralBurst = DMA_PeripheralBurst_Single;
DMA_Init(DMA_Streamx, &DMA_InitStructure);//³õʼ»¯DMA Stream
}
void MYDMA_Enable(DMA_Stream_TypeDef *DMA_Streamx,u16 ndtr)
{
DMA_Cmd(DMA_Streamx, DISABLE);
while (DMA_GetCmdStatus(DMA_Streamx) != DISABLE){}
DMA_SetCurrDataCounter(DMA_Streamx,ndtr);
DMA_Cmd(DMA_Streamx, ENABLE);
}
int main(void)
{
u16 i;
u8 t=0;
u8 j,mask=0;
NVIC_PriorityGroupConfig(NVIC_PriorityGroup_2);
delay_init(168);
uart_init(115200);
LED_Init();
TIM3_PWM_Init(84-1,1-1);
MYDMA_Config(DMA1_Stream2,DMA_Channel_5,(u32)&TIM3->CCR1,(u32)SendBuff,SEND_BUF_SIZE);
printf("DMA TEST\r\n");
j=sizeof(TEXT_TO_SEND);
for(i=0;i<SEND_BUF_SIZE;i++)
{
if(t>=j)
{
if(mask)
{
SendBuff=10;
t=0;
}else
{
SendBuff=20;
mask++;
}
}else
{
mask=0;
SendBuff=TEXT_TO_SEND;
t++;
}
}
i=0;
while(1)
{
TIM_DMACmd(TIM3,TIM_DMA_Update,ENABLE);
MYDMA_Enable(DMA1_Stream2,SEND_BUF_SIZE);
while(1)
{
if(DMA_GetFlagStatus(DMA1_Stream2,DMA_FLAG_TCIF2)!=RESET)
{
DMA_ClearFlag(DMA1_Stream2,DMA_FLAG_TCIF2);
break;
}
}
i++;
delay_ms(10);
if(i==2)
{
DS4=!DS4;
i=0;
}
}
}
用你的代码跑了下，问题出在这里，这两句放循环导致DMA一直重新使能，开头初始化调用一次就行了，
TIM_DMACmd(TIM3,TIM_DMA_Update,ENABLE);
MYDMA_Enable(DMA1_Stream2,SEND_BUF_SIZE);
这两句放循环里是不想重新使能DMA? DMA已经配置成循环模式了，DMA传输完成指定BufferSize的数量后，又会从头开始传输，不用再重新使能设置个数了。
DMA_InitStructure.DMA_Mode = DMA_Mode_Circular;
//移到循环外好了
TIM_DMACmd(TIM3,TIM_DMA_Update,ENABLE);
MYDMA_Enable(DMA1_Stream2,SEND_BUF_SIZE);
while(1)
{
while(1)
{
if(DMA_GetFlagStatus(DMA1_Stream2,DMA_FLAG_TCIF2)!=RESET)
{
DMA_ClearFlag(DMA1_Stream2,DMA_FLAG_TCIF2);
break;
}
}
}
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