转一个帖子，以供参考
1.DMA配置
void DMA_Configuration(void)
{
DMA_InitTypeDef D;
DMA_DeInit(DMA1_Channel3); //DMA1_3通道初始化U
D.DMA_PeripheralBaseAddr =(u32)&TIM3->CCR1; //DMA外设基址 TIM3_CCR1_Address
D.DMA_MemoryBaseAddr = (u32)buf; //DMA内存基址
D.DMA_DIR = DMA_DIR_PeripheralDST; //DST外设作为数据传送目的地址,SRC则作为源地址
D.DMA_BufferSize = 4; //DMA缓存大小
D.DMA_PeripheralInc = DMA_PeripheralInc_Disable; //外设地址寄存器不增加
D.DMA_MemoryInc = DMA_MemoryInc_Enable; //内存地址寄存器不增加
D.DMA_PeripheralDataSize = DMA_PeripheralDataSize_HalfWord; //外存字宽16bit
D.DMA_MemoryDataSize = DMA_MemoryDataSize_HalfWord; //内存字宽16bit
D.DMA_Mode = DMA_Mode_Normal; //工作在循环模式
//D.DMA_Mode =DMA_Mode_Circular;
D.DMA_Priority = DMA_Priority_High; //DMA置为高优先级
D.DMA_M2M = DMA_M2M_Disable; //不置为内存到内存传输
DMA_Init(DMA1_Channel3, &D); //初始化DMA1
DMA_Cmd(DMA1_Channel3, ENABLE); //DMA1_3使能
}
2.定时器PWM输出配置
u16 buf[4] = {200,400,600,800};
static void GPIO_Config(void)
{
GPIO_InitTypeDef GPIO_InitStructure;
RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM3, ENABLE); //TIM3钟源
RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA |RCC_APB2Periph_GPIOB, ENABLE); //GPIOA 配置: TIM3 channel 1 和 2 推挽复用
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP; // 复用推挽输出
GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_6;
GPIO_Init(GPIOA, &GPIO_InitStructure);
}
void TIM3_Init()
{
TIM_TimeBaseInitTypeDef TIM_TimeBaseStructure;
TIM_OCInitTypeDef TIM_OCInitStructure;
//定时器设置
TIM_TimeBaseStructure.TIM_Period = 999;
//当定时器从0计数到999，即为1000次，为一个定时周期
TIM_TimeBaseStructure.TIM_Prescaler = 0; //设置预分频：不预分频，即为36MHz
TIM_TimeBaseStructure.TIM_ClockDivision = 0; //设置时钟分频系数：不分频
TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up; //向上计数模式
//TIM_TimeBaseStructure.TIM_RepetitionCounter = 2;
TIM_TimeBaseInit(TIM3, &TIM_TimeBaseStructure);
//PWM通道1模式设置
TIM_OCInitStructure.TIM_OCMode = TIM_OCMode_PWM2; //配置为PWM模式1
TIM_OCInitStructure.TIM_OutputState =TIM_OutputState_Enable;
TIM_OCInitStructure.TIM_Pulse = buf[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_High;
//当定时器计数值小于CCR1_Val时为高电平
TIM_OC1Init(TIM3, &TIM_OCInitStructure); //使能通道1
TIM_Cmd(TIM3, ENABLE); //TIM3使能
TIM_DMACmd(TIM3, TIM_DMA_Update, ENABLE);
//TIM3 DMA请求使能,注：TIM3_Update请求对应DMA通道为DMA1_chanel3
}
3.主函数
extern u16 buf[4]；
int main（）
{
GPIO_Config(); //配置端口
TIM3_Init();
DMA_Configuration(); //配置DMA
}
可以看到PA6输出低电平占200,400,600,800的脉冲，若D.DMA_Mode=DMA_Mode_Circularl; 则200,400,600,800的脉冲循环出现。
TIM_DMACmd(TIM3, TIM_DMA_Update,ENABLE);TIM_DMA_Update对应通道3，刚开始设置TIM_DMA_CC1对应通道6无法实现本现象，原因未知。
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