求问如何能做出这样的PWM波形，试了好多方法。

K.O.Carnivist

1楼-- · 2019-10-15 03:42

本帖最后由 K.O.Carnivist 于 2016-10-6 11:50 编辑

楼主需要的波形是4个通道严格首位相接吗？

如果是的话，同时有癖不愿意用中断，可以试试这样：

用一个高级定时器做带有 Repetition Counter 的 One-Pulse，每次启动时发生6次更新。
周期是输出通道上一个脉冲的时间。
4个输出通道都配置成 Toggle，CCR 设成1。
开启任意一个通道的比较事件 DMA（任意通道，看哪个 DMA 通道空闲就好），循环写定时器的 CCER，需要哪个通道输出脉冲时把它使能。
把这个定时器做成 Slave - Trigger Mode，另外找一个定时器做 Master - Update，周期是四个脉冲的总周期。

优点是确实不用中断，通道之间波形严格相接。缺点是资源使用还是比较多的（2个定时器，1个DMA通道），而且输出波形哦定时器受限（需要高级定时器）。

需要改脉冲时间的话，改高级定时器的 ARR。
如果需要4个通道脉冲时间不一样，就再开任意一个通道的 DMA，循环写 ARR。

[mw_shl_code=cpp,true]
GPIO_InitTypeDef          GPIO_InitStructure;
DMA_InitTypeDef          DMA_InitStructure;
TIM_TimeBaseInitTypeDef    TIM_TimeBaseStructure;
TIM_OCInitTypeDef          TIM_OCInitStructure;

uint16_t CCER_Buffer[6] = {0x0203,
                           0x0213,
                           0x0312,
                           0x1302,
                           0x1202,
                           0x0202};

SystemCoreClockConfigure();                            // configure HSI as System Clock
SystemCoreClockUpdate();

SysTick_Config(SystemCoreClock / 1000);                // SysTick 1 msec interrupts

/* Clock Configuration --------------------------------------------------*/
/* DMA1 clock enable */
RCC_AHBPeriphClockCmd(RCC_AHBPeriph_DMA1, ENABLE);

/* TIM1 and GPIOA clock enable */
RCC_APB2PeriphClockCmd(RCC_APB2Periph_TIM1 | RCC_APB2Periph_GPIOA | RCC_APB2Periph_AFIO, ENABLE);

/* TIM2 clock enable */
RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM2, ENABLE);

/* GPIO Configuration ---------------------------------------------------*/
/* TIM1 channels as alternate function push-pull */
GPIO_InitStructure.GPIO_Pin =  GPIO_Pin_8 | GPIO_Pin_9 | GPIO_Pin_10 | GPIO_Pin_11;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP;
GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;

GPIO_Init(GPIOA, &GPIO_InitStructure);

/* DMA Configuration ----------------------------------------------------*/
/* DMA1 Channel2 Config */
DMA_DeInit(DMA1_Channel2);

DMA_InitStructure.DMA_PeripheralBaseAddr = (uint32_t)0x40012C20; /* TIM1_CCER */
DMA_InitStructure.DMA_MemoryBaseAddr = (uint32_t)CCER_Buffer;
DMA_InitStructure.DMA_DIR = DMA_DIR_PeripheralDST;
DMA_InitStructure.DMA_BufferSize = 6;
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_Circular;
DMA_InitStructure.DMA_Priority = DMA_Priority_High;
DMA_InitStructure.DMA_M2M = DMA_M2M_Disable;

DMA_Init(DMA1_Channel2, &DMA_InitStructure);

/* DMA1 Channel2 enable */
DMA_Cmd(DMA1_Channel2, ENABLE);

/* TIM1 Peripheral Configuration ----------------------------------------*/
/* Time Base configuration */
TIM_TimeBaseStructure.TIM_Prescaler = 0;
TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;
TIM_TimeBaseStructure.TIM_Period = 2400;
TIM_TimeBaseStructure.TIM_ClockDivision = 0;
TIM_TimeBaseStructure.TIM_RepetitionCounter = 5;

TIM_TimeBaseInit(TIM1, &TIM_TimeBaseStructure);

/* Channels Configuration in Toggle mode */
TIM_OCInitStructure.TIM_OCMode = TIM_OCMode_Toggle;
TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable;
TIM_OCInitStructure.TIM_OutputNState = TIM_OutputNState_Disable;
TIM_OCInitStructure.TIM_Pulse = 1;

TIM_OC1Init(TIM1, &TIM_OCInitStructure);
TIM_OC2Init(TIM1, &TIM_OCInitStructure);
TIM_OC3Init(TIM1, &TIM_OCInitStructure);
TIM_OC4Init(TIM1, &TIM_OCInitStructure);

/* Main Output Enable */
TIM_CtrlPWMOutputs(TIM1, ENABLE);

/* One Pulse Mode selection */
TIM_SelectOnePulseMode(TIM1, TIM_OPMode_Single);

/* Slave Mode selection: Trigger Mode */
TIM_SelectSlaveMode(TIM1, TIM_SlaveMode_Trigger);
TIM_SelectInputTrigger(TIM1, TIM_TS_ITR1);

/* TIM1 Channel1 DMA Request enable */
TIM_DMACmd(TIM1, TIM_DMA_CC1, ENABLE);

/* TIM2 Peripheral Configuration ----------------------------------------*/
/* Time Base configuration */
TIM_TimeBaseStructure.TIM_Period = 48000;
TIM_TimeBaseStructure.TIM_Prescaler = 0;
TIM_TimeBaseStructure.TIM_ClockDivision = 0;
TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;

TIM_TimeBaseInit(TIM2, &TIM_TimeBaseStructure);

/* Master Mode selection */
TIM_SelectOutputTrigger(TIM2, TIM_TRGOSource_Update);

/* Select the Master Slave Mode */
TIM_SelectMasterSlaveMode(TIM2, TIM_MasterSlaveMode_Enable);

/* TIM2 counter enable */
TIM_Cmd(TIM2, ENABLE);
[/mw_shl_code]