STM32F103 利用TIM4进行DMA比较输出遇到问题

只看该作者 · 2012-5-20 23:58

是这样的，我想利用定时器2的CH1通道，比较输出波形，然后利用DMA的方式来输出。周期为1000us，分别输出50%, 37.5%, 25%占空比的波形。结果发现了问题。
如果我的DMA设置为单次的，用逻辑分析仪捕获到的波形是对的，如下图所示，3个高电平分别为500us , 375us , 250us ;

但是，如果我选择周期性DMA，则波形出现变化，经过分析，就是最后一次的DMA和第一次的DMA重合了，表现的波形如下所示：

这个问题已经折磨我好久了，真的不知道怎么解决。
希望有知道的人能帮助我一下，到底这是怎么回事啊？

只看该作者 · 2012-5-20 23:59

实在是没辙了，只能求助各位。

只看该作者 · 2012-5-21 00:07

GPIO_InitTypeDef GPIO_InitStruct;
DMA_InitTypeDef DMA_InitStructure;
TIM_TimeBaseInitTypeDef  TIM_TimeBaseStructure;
TIM_OCInitTypeDef  TIM_OCInitStructure;

uint16_t TimerPeriod = 0;

RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOB | RCC_APB2Periph_AFIO, ENABLE);
RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM4, ENABLE);
RCC_AHBPeriphClockCmd(RCC_AHBPeriph_DMA1, ENABLE);

/* GPIOA Configuration: Channel 2 as alternate function push-pull */
GPIO_InitStruct.GPIO_Pin =  GPIO_Pin_6;
GPIO_InitStruct.GPIO_Mode = GPIO_Mode_AF_PP;
GPIO_InitStruct.GPIO_Speed = GPIO_Speed_50MHz;
GPIO_Init(GPIOB, &GPIO_InitStruct);

/* DMA1 Channel5 Config */
DMA_DeInit(DMA1_Channel1);

DMA_InitStructure.DMA_PeripheralBaseAddr = (uint32_t)TIM4_CCR1_Address;
DMA_InitStructure.DMA_MemoryBaseAddr = (uint32_t)SRC_Buffer;
DMA_InitStructure.DMA_DIR = DMA_DIR_PeripheralDST;
DMA_InitStructure.DMA_BufferSize = 3;
DMA_InitStructure.DMA_PeripheralInc = DMA_PeripheralInc_Disable;
DMA_InitStructure.DMA_MemoryInc = DMA_MemoryInc_Enable;
DMA_InitStructure.DMA_PeripheralDataSize = DMA_PeripheralDataSize_HalfWord;
DMA_InitStructure.DMA_MemoryDataSize = DMA_MemoryDataSize_HalfWord;
DMA_InitStructure.DMA_Mode = DMA_Mode_Normal;
DMA_InitStructure.DMA_Priority = DMA_Priority_High;
DMA_InitStructure.DMA_M2M = DMA_M2M_Disable;

DMA_Init(DMA1_Channel1, &DMA_InitStructure);

/* DMA1 Channel5 enable */
DMA_Cmd(DMA1_Channel1, ENABLE);

/* Compute the value to be set in ARR register to generate signal frequency at 17.57 Khz */
TimerPeriod = (SystemCoreClock / 1000 ) - 1;
/* Compute CCR1 value to generate a duty cycle at 50% */
SRC_Buffer[0] = (uint16_t) (((uint32_t) 5 * (TimerPeriod - 1)) / 10);
/* Compute CCR1 value to generate a duty cycle at 37.5% */
SRC_Buffer[1] = (uint16_t) (((uint32_t) 375 * (TimerPeriod - 1)) / 1000);
/* Compute CCR1 value to generate a duty cycle at 25% */
SRC_Buffer[2] = (uint16_t) (((uint32_t) 25 * (TimerPeriod - 1)) / 100);

/* TIM4 Peripheral Configuration --------------------------------------------*/
/* Time Base configuration */
TIM_TimeBaseStructure.TIM_Prescaler = 0;
TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;
TIM_TimeBaseStructure.TIM_Period = TimerPeriod;
TIM_TimeBaseStructure.TIM_ClockDivision = 0;
TIM_TimeBaseInit(TIM4, &TIM_TimeBaseStructure);

/* Channel 2 Configuration in PWM mode */
TIM_OCInitStructure.TIM_OCMode = TIM_OCMode_PWM2;
TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable;
// TIM_OCInitStructure.TIM_OutputNState = TIM_OutputNState_Enable;
TIM_OCInitStructure.TIM_Pulse = SRC_Buffer[0];
TIM_OCInitStructure.TIM_OCPolarity = TIM_OCPolarity_Low;
// TIM_OCInitStructure.TIM_OCNPolarity = TIM_OCNPolarity_Low;
TIM_OCInitStructure.TIM_OCIdleState = TIM_OCIdleState_Set;
// TIM_OCInitStructure.TIM_OCNIdleState = TIM_OCIdleState_Reset;

TIM_OC1Init(TIM4, &TIM_OCInitStructure);

/* TIM4 Update DMA Request enable */
TIM_DMACmd(TIM4, TIM_DMA_CC1, ENABLE);

// TIM_CCPreloadControl(TIM4, ENABLE);

/* TIM1 counter enable */
TIM_Cmd(TIM4, ENABLE);

/* Main Output Enable */
TIM_CtrlPWMOutputs(TIM4, ENABLE);

只看该作者 · 2012-6-20 15:37

结贴。

只看该作者 · 2012-6-20 17:37

路过。。。。:lol

只看该作者 · 2012-8-31 16:06

3# honami520
楼主还没说说如何好的呢

我碰到了一样的问题，还没解决

STM32F103 利用TIM4进行DMA比较输出遇到问题

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