DAC—數(shù)模轉(zhuǎn)換器

DAC即是數(shù)模轉(zhuǎn)換器，就是將數(shù)字量轉(zhuǎn)換成模擬量，原理什么的大家應(yīng)該都懂，直接跳入如何使用：
STM32的DAC使用起來非常簡單，首先將連接DAC通道的GPIO引腳配置為模擬狀態(tài)，然后初始化DAC，一共只有四個參數(shù)需要初始化，其中最重要的是觸發(fā)源：這個參數(shù)的作用是，每來一個觸發(fā)源信號，DAC就刷新一次輸出，也就是將需要轉(zhuǎn)換的數(shù)字量轉(zhuǎn)換為電壓輸出，這里選擇定時器2作為觸發(fā)源。
代碼：

void DAC_Config(void)

{

GPIO_InitTypeDef GPIO_InitStructure;

DAC_InitTypeDef DAC_InitStructure;

DAC_TRIGTIM_Config();//定時器配置，見第2點(diǎn)

RCC_AHBPeriphClockCmd(RCC_AHBPeriph_GPIOA,ENABLE);

RCC_APB1PeriphClockCmd(RCC_APB1Periph_DAC1,ENABLE);

GPIO_InitStructure.GPIO_Pin = GPIO_Pin_5;

GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AN; //模擬

GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_NOPULL;

GPIO_Init(GPIOA,&GPIO_InitStructure);

DAC_InitStructure.DAC_Buffer_Switch=DAC_BufferSwitch_Disable; //增大電流的，不需要

DAC_InitStructure.DAC_Trigger=DAC_Trigger_T2_TRGO; //定時器2做觸發(fā)源

DAC_InitStructure.DAC_WaveGeneration=DAC_WaveGeneration_None; //不需要

DAC_InitStructure.DAC_LFSRUnmask_TriangleAmplitude = DAC_LFSRUnmask_Bits2_0;//這個是針對上一個參數(shù)的，所以也不重要

DAC_Init(DAC1,DAC_Channel_2,&DAC_InitStructure);

DAC_SetChannel2Data(DAC1,DAC_Align_12b_R,0);//設(shè)置一下初始值，其實(shí)也可以不用

DAC_Cmd(DAC1,DAC_Channel_2,ENABLE);

}

void DAC_TRIGTIM_Config(void)

{

TIM_TimeBaseInitTypeDef TIM_TimeBaseStructure;

RCC_APB1PeriphClockCmd(DAC_TRIGTIM_CLK, ENABLE);

TIM_TimeBaseStructInit(&TIM_TimeBaseStructure);

TIM_TimeBaseStructure.TIM_Period = 36000-1; //定時1ms

TIM_TimeBaseStructure.TIM_Prescaler = 2-1; //二分頻，計(jì)時器頻率36M

TIM_TimeBaseStructure.TIM_ClockDivision = 0x0;

TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;

TIM_TimeBaseInit(DAC_TRIGTIM, &TIM_TimeBaseStructure);

TIM_SelectOutputTrigger(DAC_TRIGTIM, TIM_TRGOSource_Update);//選擇輸出Trigger信號

TIM_Cmd(DAC_TRIGTIM, ENABLE);

做好上面兩步，DAC就可以使用了，下面是使用DMA模式的配置

uint16_t OUTPUT_BUFFER[20]={1500,1800,2100,2400,2700,3000,3300,3600,3900,4095,

4095,3900,3600,3300,3000,2700,2400,2100,1800,1500};

void DAC_DMA_Config(void)

{

DMA_InitTypeDef DMA_InitStructure;

RCC_AHBPeriphClockCmd(RCC_AHBPeriph_DMA2, ENABLE);

DMA_DeInit(DMA2_Channel4);

DMA_InitStructure.DMA_PeripheralBaseAddr = DAC_DHR12R2_ADDR;//DHR12R2寄存器的地址

DMA_InitStructure.DMA_MemoryBaseAddr = (uint32_t)&OUTPUT_BUFFER;//內(nèi)存緩沖區(qū)

DMA_InitStructure.DMA_DIR = DMA_DIR_PeripheralDST;//發(fā)向外設(shè)(DAC)

DMA_InitStructure.DMA_BufferSize = 20;//數(shù)據(jù)個數(shù)

DMA_InitStructure.DMA_PeripheralInc = DMA_PeripheralInc_Disable;//外設(shè)地址不增加

DMA_InitStructure.DMA_MemoryInc = DMA_MemoryInc_Enable;//增加

DMA_InitStructure.DMA_PeripheralDataSize = DMA_PeripheralDataSize_HalfWord;//16位

DMA_InitStructure.DMA_MemoryDataSize = DMA_MemoryDataSize_HalfWord;

DMA_InitStructure.DMA_Mode = DMA_Mode_Circular;//循環(huán)模式

DMA_InitStructure.DMA_Priority = DMA_Priority_VeryHigh;

DMA_InitStructure.DMA_M2M = DMA_M2M_Disable;//禁止

DMA_Init(DMA2_Channel4, &DMA_InitStructure);

DMA_Cmd(DMA2_Channel4, ENABLE);

DAC_DMACmd(DAC1,DAC_Channel_2,ENABLE);

}