STM32f030f4p6 DMA驱动2811 为什么PWM频率达不到800KHZ

l441867854 提问时间：2019-7-12 11:16 /

#define TIM_PERIOD 59 // Number of CPU cycles that will constitute 1 period
#define PWM_HIGH_WIDTH 45 // Duty cycle of pwm signal for a logical 1 to be read by the ws2812 chip. //Duty cycle = PWM_HIGH_WIDTH/TIM_PERIOD*100
#define PWM_LOW_WIDTH 10
uint8_t ledBuff[69]={0};

void TIM3_PWM_Init(void){ GPIO_InitTypeDef GPIO_InitStructure; TIM_TimeBaseInitTypeDef TIM_TimeBaseStructure; TIM_OCInitTypeDef TIM_OCInitStructure; DMA_InitTypeDef DMA_InitStructure; /* 配置相应引脚PB1*/ RCC_AHBPeriphClockCmd(RCC_AHBPeriph_GPIOB|RCC_AHBPeriph_DMA1, ENABLE); GPIO_InitStructure.GPIO_Pin = GPIO_Pin_1; GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF; GPIO_InitStructure.GPIO_OType = GPIO_OType_PP; GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_UP; GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz; GPIO_PinAFConfig(GPIOB, GPIO_PinSource1, GPIO_AF_1); GPIO_Init(GPIOB, &GPIO_InitStructure); RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM3, ENABLE); //使能定时器3时钟 TIM_TimeBaseStructure.TIM_Period = TIM_PERIOD;// 设置自动重装周期值 TIM_TimeBaseStructure.TIM_Prescaler = 0;//设置预分频值 TIM_TimeBaseStructure.TIM_ClockDivision = 0;//设置时钟分割 TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;//向上计数 TIM_TimeBaseInit(TIM3, &TIM_TimeBaseStructure); //初始化定时器3 TIM_OCInitStructure.TIM_OCMode = TIM_OCMode_PWM1;// PWM2模式 TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable;//比较输出使能 TIM_OCInitStructure.TIM_Pulse = 0; TIM_OCInitStructure.TIM_OCPolarity = TIM_OCPolarity_High;//输出高 TIM_OC4Init(TIM3, &TIM_OCInitStructure); TIM_OC4PreloadConfig(TIM3, TIM_OCPreload_Enable);//使能预装载寄存器 DMA_DeInit(DMA1_Channel3); DMA_InitStructure.DMA_PeripheralBaseAddr = (uint32_t)&(TIM3->CCR4); // physical address of Timer 3 CCR4 DMA_InitStructure.DMA_MemoryBaseAddr = (uint32_t)ledBuff; // this is the buffer memory DMA_InitStructure.DMA_DIR = DMA_DIR_PeripheralDST; // data shifted from memory to peripheral DMA_InitStructure.DMA_BufferSize = sizeof(ledBuff); DMA_InitStructure.DMA_PeripheralInc = DMA_PeripheralInc_Disable; DMA_InitStructure.DMA_MemoryInc = DMA_MemoryInc_Enable; // automatically increase buffer index DMA_InitStructure.DMA_PeripheralDataSize = DMA_PeripheralDataSize_HalfWord; DMA_InitStructure.DMA_MemoryDataSize = DMA_MemoryDataSize_HalfWord; DMA_InitStructure.DMA_Mode = DMA_Mode_Normal; // stop DMA feed after buffer size is reached DMA_InitStructure.DMA_Priority = DMA_Priority_High; DMA_InitStructure.DMA_M2M = DMA_M2M_Disable; DMA_Init(DMA1_Channel3, &DMA_InitStructure); TIM_DMACmd(TIM3, TIM_DMA_CC4, ENABLE); }

void Ws2812_reflash(void){ DMA_SetCurrDataCounter(DMA1_Channel3, sizeof(ledBuff)); DMA_Cmd(DMA1_Channel3,ENABLE); TIM_Cmd(TIM3, ENABLE); while(!DMA_GetFlagStatus(DMA1_FLAG_TC3)); TIM_Cmd(TIM3, DISABLE); DMA_Cmd(DMA1_Channel3,DISABLE); DMA_ClearFlag(DMA1_FLAG_TC3); }void Set2812RGB(uint8_t redcolor,uint8_t greencolor,uint8_t bluecolor){ uint8_t i=0; uint32_t rgb_value=redcolor<<16|greencolor<<8|bluecolor; for(i=0;i<69;i++) { if((rgb_value<<i)&0x800000) { ledBuff[i]=PWM_HIGH_WIDTH; } else { ledBuff[i]=PWM_LOW_WIDTH; } } }

int main(void){ //delay_init(); TIM3_PWM_Init(); while(1) { //TIM_SetCompare2(TIM1, 10); //ws2812_senddata(color,LED_COUNT); Set2812RGB(0,57,0); Ws2812_reflash(); //delay_ms(10); } }