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前段時間師兄拜托寫一個單片機(jī)代碼，由于之前沒整過，在這記錄一下。也希望可以幫助到正在學(xué)這個的朋友們.stm32F4并不支持自動生成正弦波，事先在正弦波上找500個點(diǎn)存在一個數(shù)組里，然后當(dāng)每一個時鐘到來的時候，dac就會輸出電壓值。
void sin_Generation(void) {u16 n;for(n=0;n<tableSize;n++) {sinTable[n] = (sin(2*PI*n/tableSize)+1)*2047;}
經(jīng)過線性轉(zhuǎn)換后，數(shù)字輸入會轉(zhuǎn)換為 0 到 VREF+ 之間的輸出電壓。各 DAC 通道引腳的模擬輸出電壓通過以下公式確定：
DACoutput =Vref*dor/4095
接下來就是定時器和GPIO的配置，以及為了避免占用CPU的dma操作
void TIM6_Configuration(void)
{
RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM6, ENABLE);
TIM_PrescalerConfig(TIM6, 83, TIM_PSCReloadMode_Update);
TIM_SetAutoreload(TIM6, 70)
TIM_SelectOutputTrigger(TIM6, TIM_TRGOSource_Update)；
TIM_Cmd(TIM6, ENABLE)
}
定時器的arr值和psc值得·設(shè)置可以改變輸出波形的頻率，這里的頻率為50hz
void GPIO_Configuration(void)
{
GPIO_InitTypeDef GPIO_InitStructure;
RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOA, ENABLE);
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_4;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AN;
GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_NOPULL;
GPIO_Init(GPIOA, &GPIO_InitStructure);
}
void DAC_DMA_Configuration(void)
{
DAC_InitTypeDef DAC_InitStructure;
DMA_InitTypeDef DMA_InitStructure;
RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_DMA1, ENABLE);
RCC_APB1PeriphClockCmd(RCC_APB1Periph_DAC, ENABLE);
DAC_InitStructure.DAC_Trigger = DAC_Trigger_T6_TRGO;
DAC_InitStructure.DAC_WaveGeneration = DAC_WaveGeneration_None；
DAC_InitStructure.DAC_OutputBuffer = DAC_OutputBuffer_Disable;
DAC_Init(DAC_Channel_1, &DAC_InitStructure);
DMA_DeInit(DMA1_Stream5);
DMA_InitStructure.DMA_Channel = DMA_Channel_7;
DMA_InitStructure.DMA_PeripheralBaseAddr = DAC_DHR12R1_ADDRESS;
DMA_InitStructure.DMA_Memory0BaseAddr = (uint32_t)&sinTable;
DMA_InitStructure.DMA_BufferSize = tableSize;
DMA_InitStructure.DMA_PeripheralDataSize = DMA_PeripheralDataSize_HalfWord;
DMA_InitStructure.DMA_MemoryDataSize = DMA_PeripheralDataSize_HalfWord;
DMA_InitStructure.DMA_DIR = DMA_DIR_MemoryToPeripheral;
DMA_InitStructure.DMA_PeripheralInc = DMA_PeripheralInc_Disable;
DMA_InitStructure.DMA_MemoryInc = DMA_MemoryInc_Enable;
DMA_InitStructure.DMA_Mode = DMA_Mode_Circular;
DMA_InitStructure.DMA_Priority = DMA_Priority_High;
DMA_InitStructure.DMA_FIFOMode = DMA_FIFOMode_Disable;
DMA_InitStructure.DMA_FIFOThreshold = DMA_FIFOThreshold_HalfFull;
DMA_InitStructure.DMA_MemoryBurst = DMA_MemoryBurst_Single;
DMA_InitStructure.DMA_PeripheralBurst = DMA_PeripheralBurst_Single;
DMA_Init(DMA1_Stream5, &DMA_InitStructure);
DMA_Cmd(DMA1_Stream5, ENABLE);
DAC_Cmd(DAC_Channel_1, ENABLE);
DAC_DMACmd(DAC_Channel_1, ENABLE);
}
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