STM32f030f4p6 DMA驱动2811 为什么PWM频率达不到800KHZ
本帖最后由 l441867854 于 2019-7-13 13:34 编辑#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={0};
void TIM3_PWM_Init(void)
{
GPIO_InitTypeDefGPIO_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=PWM_HIGH_WIDTH;
}
else
{
ledBuff=PWM_LOW_WIDTH;
}
}
int main(void)
{
//delay_init();
TIM3_PWM_Init();
while(1)
{
Set2812RGB(0,57,0);
Ws2812_reflash();
}
}
file:///C:\Users\Administrator\AppData\Roaming\Tencent\Users\441867853\QQ\WinTemp\RichOle\WEUORX)~(R
测试出来的PWM波形频率只有8K 为什么！！！
本帖最后由 toofree 于 2019-7-12 19:35 编辑
程序问题较多
uint8_t ledBuff={0}; -- 定义是8位数组；
ledBuff=PWM_HIGH_WIDTH;--这样赋值为哪般？ledBuff是指针，不是得给数组的元素赋值吗？赋完值后，指针也要增加的。或者改成ledBuff = PWM_HIGH_WIDTH;
if((rgb_value<<i)&0x800000)---这里的 rgb_value<<i 是个什么东西？i的取值可是0到68呀！
既然你的ledBuff是8位的数组，那么DMA传数也得是8位的。
DMA_InitStructure.DMA_PeripheralDataSize = DMA_PeripheralDataSize_HalfWord;
DMA_InitStructure.DMA_MemoryDataSize = DMA_MemoryDataSize_HalfWord;
是不是应该改成字节呢？定时器是16位的，初始化高8位为0即可，DMA只传输低8位。
DMA_InitStructure.DMA_PeripheralDataSize = DMA_PeripheralDataSize_Byte;
DMA_InitStructure.DMA_MemoryDataSize = DMA_MemoryDataSize_Byte;
另外，你对WS2812灯的理解是不是正确呢？这个灯是RGB888，正确点一颗灯，需要发送24个脉冲。依此类推，点2颗灯需要48个脉冲，3灯72个脉冲。而你用的ledBuff，69个元素，与谁都不搭边啊。
哪位高手帮忙看下！！ 时钟使用的是默认库函数设置，没有更改。单独输出PWM输出的是正确的，但是DMA加上以后频率就变了。 高手高手 高高手 帮忙看下 Any one can give me a solution，help!! toofree 发表于 2019-7-12 19:27
程序问题较多
uint8_t ledBuff={0}; -- 定义是8位数组；
ledBuff=PWM_HIGH_WIDTH;--这样赋值为哪般？ ...
1，是前面的数组位数定义错了，改成16位重新测试了一下，正常了。非常感谢
2，i在for里面有增加。本来是24，因为频率出不来，就改了。
3 这个程序只是初次来测试电平时间用的，只点一颗灯， 只是为了在后面加一个低电平复位时间。 非常感谢
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