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废话不多说，因为激光振镜驱动需要正弦波与三角波，为了省事，直接通过STM32F407实现DAC的DMA输出，省CPU资源；经过调试，在0-NkHZ之内都可以实现，目前采样点为500个；上数据吧；其中三角波自动生成500个数据，在初始化的时候实现fun12【500】个数据的填充即可；
void tri_angle_fun(void)
{
?? ?int count;
?? ? ?for(count=0;count<250;count++)
?? ? ? ? {fun12[count] =(4095-((u16)(16.38 * count)));}
?? ? ?for(count=251;count<501;count++)
? ? ?? ?{fun12[count] = ((u16)(16.38 * (count-250)));}
}
//4095 /250 =16.38 ；DAC为12bit，其中最高4096，最低位0；500个点分布；原理很简单啦，就是按线性每次填充就OL了；
正弦波直接借用网络上的数据表实现：
const u16 function[500] = { ?
?? ?2048,2073,2099,2125,2150,2176,2202,2227,2253,2279,2304,2330,2355,2380,
?? ?2406,2431,2456,2482,2507,2532,2557,2582,2606,2631,2656,2680,2705,2729,2753,
?? ?2777,2801,2825,2849,2872,2896,2919,2942,2966,2988,3011,3034,3056,3079,3101,
?? ?3123,3145,3166,3188,3209,3230,3251,3272,3292,3313,3333,3353,3372,3392,3411,
?? ?3430,3449,3468,3486,3504,3522,3540,3558,3575,3592,3609,3625,3641,3657,3673,
?? ?3689,3704,3719,3734,3748,3762,3776,3790,3803,3816,3829,3842,3854,3866,3878,
?? ?3889,3900,3911,3921,3932,3942,3951,3961,3970,3978,3987,3995,4003,4010,4017,
?? ?4024,4031,4037,4043,4048,4054,4059,4063,4068,4072,4075,4079,4082,4085,4087,
?? ?4089,4091,4092,4094,4094,4095,4095,4095,4094,4094,4092,4091,4089,4087,4085,
?? ?4082,4079,4075,4072,4068,4063,4059,4054,4048,4043,4037,4031,4024,4017,4010,
?? ?4003,3995,3987,3978,3970,3961,3951,3942,3932,3921,3911,3900,3889,3878,3866,
?? ?3854,3842,3829,3816,3803,3790,3776,3762,3748,3734,3719,3704,3689,3673,3657,
?? ?3641,3625,3609,3592,3575,3558,3540,3522,3504,3486,3468,3449,3430,3411,3392,
?? ?3372,3353,3333,3313,3292,3272,3251,3230,3209,3188,3166,3145,3123,3101,3079,
?? ?3056,3034,3011,2988,2966,2943,2919,2896,2872,2849,2825,2801,2777,2753,2729,
?? ?2705,2680,2656,2631,2606,2582,2557,2532,2507,2482,2456,2431,2406,2381,2355,
?? ?2330,2304,2279,2253,2227,2202,2176,2150,2125,2099,2073,2048,2022,1996,1970,
?? ?1945,1919,1893,1868,1842,1816,1791,1765,1740,1715,1689,1664,1639,1613,1588,
?? ?1563,1538,1513,1489,1464,1439,1415,1390,1366,1342,1318,1294,1270,1246,1223,
?? ?1199,1176,1153,1129,1107,1084,1061,1039,1016,994,972,950,929,907,886,865,
?? ?844,823,803,782,762,742,723,703,684,665,646,627,609,591,573,555,537,520,
?? ?503,486,470,454,438,422,406,391,376,361,347,333,319,305,292,279,266,253,
?? ?241,229,217,206,195,184,174,163,153,144,134,125,117,108,100,92,85,78,71,
?? ?64,58,52,47,41,36,32,27,23,20,16,13,10,8,6,4,3,1,1,0,0,0,1,1,3,4,6,8,10,
?? ?13,16,20,23,27,32,36,41,47,52,58,64,71,78,85,92,100,108,117,125,134,144,
?? ?153,163,174,184,195,206,217,229,241,253,266,279,292,305,319,333,347,361,
?? ?376,391,406,422,438,454,470,486,503,520,537,555,573,591,609,627,646,665,
?? ?684,703,723,742,762,782,803,823,844,865,886,907,929,950,972,994,1016,1039,
?? ?1061,1084,1107,1129,1153,1176,1199,1223,1246,1270,1294,1318,1342,1366,1390,
?? ?1415,1439,1464,1489,1513,1538,1563,1588,1613,1639,1664,1689,1715,1740,1765,
?? ?1791,1816,1842,1868,1893,1919,1945,1970,1996,2022}; ?? ?
由于STM32的DAC具有几种触发模式,本次采用定时器触发，选用TIM6定时器：初始化如下：
? TIM_TimeBaseInitTypeDef TIM6_TimeBase;
? RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM6, ENABLE);
? TIM_TimeBaseStructInit(&TIM6_TimeBase);?
? TIM6_TimeBase.TIM_Period ? ? ? ?= 168;? ? ? ? ?
? TIM6_TimeBase.TIM_Prescaler ? ? = 0;? ? ? ?
? TIM6_TimeBase.TIM_ClockDivision = 0; ? ?
? TIM6_TimeBase.TIM_CounterMode ? = TIM_CounterMode_Up; ?
? TIM_TimeBaseInit(TIM6, &TIM6_TimeBase);
? TIM_SelectOutputTrigger(TIM6, TIM_TRGOSource_Update);
? TIM_Cmd(TIM6, ENABLE);
因为我的是STM32F407，直接168Mhz走起；分频168；
//DAC1的PA4脚初始化及DMA初始化；
void Dac1_Init(void)
{ ?
? GPIO_InitTypeDef gpio_A;
?? ?DAC_InitTypeDef DAC_INIT;
? DMA_InitTypeDef DMA_INIT;
?? ?
? RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOA, ENABLE); ? ? ? ? ? ? ? ? ?
? RCC_APB1PeriphClockCmd(RCC_APB1Periph_DAC, ENABLE);
? RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_DMA1, ENABLE);
? gpio_A.GPIO_Pin ?= GPIO_Pin_4;
? gpio_A.GPIO_Mode = GPIO_Mode_AN;
? gpio_A.GPIO_PuPd = GPIO_PuPd_NOPULL;
? GPIO_Init(GPIOA, &gpio_A);
? DAC_INIT.DAC_Trigger ? ? ? ?= DAC_Trigger_T6_TRGO;
? DAC_INIT.DAC_WaveGeneration = DAC_WaveGeneration_None;
? DAC_INIT.DAC_OutputBuffer ? = DAC_OutputBuffer_Enable;
? DAC_Init(DAC_Channel_1, &DAC_INIT);
? DAC_SetChannel1Data(DAC_Align_12b_R,0X0000);
?? ?DAC_SoftwareTriggerCmd(DAC_Channel_1,ENABLE);
?? ?
? DMA_DeInit(DMA1_Stream5);
? DMA_INIT.DMA_Channel ? ? ? ? ? ?= DMA_Channel_7;?
? DMA_INIT.DMA_PeripheralBaseAddr = (uint32_t)DAC_DHR12R1_ADDR;//fun12
?DMA_INIT.DMA_Memory0BaseAddr ? ?= (uint32_t)&fun12;? ?//对应FUN12的500个数据首地址，填充后自动啪啪输出吧；不要想歪了：）
? DMA_INIT.DMA_DIR ? ? ? ? ? ? ? ?= DMA_DIR_MemoryToPeripheral;
? DMA_INIT.DMA_BufferSize ? ? ? ? = 500; //每次输出500个点；
? DMA_INIT.DMA_PeripheralInc ? ? ?= DMA_PeripheralInc_Disable;
? DMA_INIT.DMA_MemoryInc ? ? ? ? ?= DMA_MemoryInc_Enable;
? DMA_INIT.DMA_PeripheralDataSize = DMA_PeripheralDataSize_HalfWord;
? DMA_INIT.DMA_MemoryDataSize ? ? = DMA_MemoryDataSize_HalfWord;
? DMA_INIT.DMA_Mode ? ? ? ? ? ? ? = DMA_Mode_Circular; //自动循环输出模式；
? DMA_INIT.DMA_Priority ? ? ? ? ? = DMA_Priority_High;
? DMA_INIT.DMA_FIFOMode ? ? ? ? ? = DMA_FIFOMode_Disable; ? ? ? ??
? DMA_INIT.DMA_FIFOThreshold ? ? ?= DMA_FIFOThreshold_HalfFull;
? DMA_INIT.DMA_MemoryBurst ? ? ? ?= DMA_MemoryBurst_Single;
? DMA_INIT.DMA_PeripheralBurst ? ?= DMA_PeripheralBurst_Single;
? DMA_Init(DMA1_Stream5, &DMA_INIT);
? DMA_Cmd(DMA1_Stream5, ENABLE);
? DAC_Cmd(DAC_Channel_1, ENABLE);
? DAC_DMACmd(DAC_Channel_1, ENABLE);
}
#define ? TIM_PERIOD ? ? ? ?((168000000)/((500)*(OUT_FREQ))) // Autoreload reg value =168000000/500 = 336 000 ;
#define ? OUT_FREQ ? ? ? ? ?4366?
//1 ?HZ ? OUT_FREQ = 336; ?//33600+6720=0.1
//120HZ ? OUT_FREQ = 44000 ?// 8.3uS ? ?// ? RESULT = (44000 - 336)*xishu; ?XISHU = 1-100%;
//#define ? DAC_DHR12RD_Address 0x40007408
通过修改OUT_FREQ就可以改变频率，数值越大，频率也越高；
通过拷贝数组的值，乘以一个系数，就可以改变幅度了：
比如要改变正弦波的幅度：
void copy_arr(u16 fun11[],const u16 function[],int n)
{
?? ?int count;
?? ?for(count=0;count<n+1;count++)
?? ?{
?? ??? ?fun11[count] =(u16)(function[count]*0.5); //0.5就是系数啦；
?? ?}
}
这个时候调用的初始化地址应该是&fun11的首地址啦；三角波类似啦，在计算的时候就弄个系数就OL了；简单，明了，真实有效；
就这样：OL了，期望可以帮助到更多的工程师；攻城狮是真辛苦！；
Q-Q :417179642? ?啦啦啦啦啦啦啦啦啦啦啦啦啦.....
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