STM32F103有双DAC通道，利用DMA实现2个波形输出
#include "stm32f10x.h" //DAC1,2初始化 void dac_init(void) { RCC->APB2ENR |= RCC_APB2ENR_IOPAEN; //开启端口A时钟 RCC->APB1ENR |= RCC_APB1ENR_DACEN; //开启DAC时钟 GPIOA->CRL &= 0xff00ffff; //PA4,PA5模拟输入 DAC->CR = DAC_CR_TEN1 | DAC_CR_TEN2; //开启触发使能才能设置触发模式 //开启DAC,关闭输出缓存,TIM6 TRGO触发,DMA使能 DAC->CR |= DAC_CR_EN1 | DAC_CR_BOFF1 | DAC_CR_DMAEN1 | \ DAC_CR_EN2 | DAC_CR_BOFF2 | DAC_CR_DMAEN2; //必须关闭缓冲才能输出低于0.5V电压 } //DMA2初始化 void dma2_init(unsigned int cpar, unsigned int cmar, unsigned int cndtr) { RCC->AHBENR |= RCC_AHBENR_DMA2EN; //开启DMA2时钟 DMA2_Channel3->CPAR = cpar; //外设地址 DMA2_Channel3->CMAR = cmar; //存储器地址 DMA2_Channel3->CNDTR = cndtr; //传输数据量 //通道开启,从存储器读,循环,外设不自增,存储器自增 //外设32位数据,存储器32位数据,优先级最高,非存储器到存储器 DMA2_Channel3->CCR = DMA_CCR3_EN | DMA_CCR3_DIR | DMA_CCR3_CIRC | \ DMA_CCR3_MINC | DMA_CCR3_PSIZE_1 | DMA_CCR3_MSIZE_1 | \ DMA_CCR3_PL_0 | DMA_CCR3_PL_1; } //TIM6初始化 void tim6_init(unsigned short arr, unsigned short psc) { RCC->APB1ENR |= RCC_APB1ENR_TIM6EN; //开启TIM6时钟 TIM6->PSC = psc; //预分频器 TIM6->ARR = arr; //自动重装载 TIM6->CR2 &= 0xff8f; TIM6->CR2 |= TIM_CR2_MMS_1; //更新事件用作TRGO TIM6->CR1 &= 0xff70; TIM6->CR1 |= TIM_CR1_CEN | TIM_CR1_ARPE; //使能计数器,非单脉冲模式,自动重装载 }
初始化RCC时钟为72MHz，正弦波1000点，2个波形，一个反相，一个幅度改变
for(i = 0; i < 1000; i++) { sw[i] = 4095 - sine_wave[i]; sw[i] <<= 16; sw[i] += sine_wave[i] / 3; } dma2_init((unsigned int)&DAC->DHR12RD, (unsigned int)sw, 1000); dac_init(); tim6_init(7200, 0);
ARR为7199，PSC为0，72M/7199/1000=10Hz波形频率，修改预分频和重装载数值可以改变波形频率
计算公式：f=fosc/n/(arr+1)/(psc+1)
f-波形频率
n-波形点数
arr-定时器计数，不能为0
psc-时钟分频系数
fosc-系统时钟，一般PLL后为72MHz
| 
