STM32F0系列用timer控制ADC取樣，然後DMA傳輸到Memory或者DAC
uint16_t RegularConvData_Tab[32];
void ADC1_DMA_Config(void)
{ADC_InitTypeDef ADC_InitStructure;
GPIO_InitTypeDef GPIO_InitStructure;
DMA_InitTypeDef DMA_InitStructure;
/* ADC1 DeInit */
ADC_DeInit(ADC1);
/* GPIOC Periph clock enable */
RCC_AHBPeriphClockCmd(RCC_AHBPeriph_GPIOA, ENABLE);
/* ADC1 Periph clock enable */
RCC_APB2PeriphClockCmd(RCC_APB2Periph_ADC1, ENABLE);
/* DMA1 clock enable */
RCC_AHBPeriphClockCmd(RCC_AHBPeriph_DMA1 , ENABLE);
/* Configure ADC Channel2 as analog input */
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_2 ;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AN;
GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_NOPULL ;
GPIO_Init(GPIOA, &GPIO_InitStructure);
/* DMA1 Channel1 Config */
DMA_DeInit(DMA1_Channel1);
DMA_InitStructure.DMA_PeripheralBaseAddr = (uint32_t)ADC1_DR_Address;
DMA_InitStructure.DMA_MemoryBaseAddr = (uint32_t)RegularConvData_Tab;
DMA_InitStructure.DMA_DIR = DMA_DIR_PeripheralSRC;
DMA_InitStructure.DMA_BufferSize = 32;
DMA_InitStructure.DMA_PeripheralInc = DMA_PeripheralInc_Disable;
DMA_InitStructure.DMA_MemoryInc = DMA_MemoryInc_Enable;
DMA_InitStructure.DMA_PeripheralDataSize = DMA_PeripheralDataSize_HalfWord;
DMA_InitStructure.DMA_MemoryDataSize = DMA_MemoryDataSize_HalfWord;
DMA_InitStructure.DMA_Mode = DMA_Mode_Circular;
DMA_InitStructure.DMA_Priority = DMA_Priority_High;
DMA_InitStructure.DMA_M2M = DMA_M2M_Disable;
DMA_Init(DMA1_Channel1, &DMA_InitStructure);
/* DMA1 Channel1 enable */
DMA_Cmd(DMA1_Channel1, ENABLE);
/*DMA傳輸完成中斷使能*/
DMA_ITConfig(DMA1_Channel1, DMA_IT_TC, ENABLE)
/* ADC DMA request in circular mode */ADC_DMARequestModeConfig(ADC1, ADC_DMAMode_Circular);
/* Enable ADC_DMA */
ADC_DMACmd(ADC1, ENABLE);
/* Initialize ADC structure */
ADC_StructInit(&ADC_InitStructure);
/* Configure the ADC1 in continous mode withe a resolutuion equal to 12 bits */
ADC_InitStructure.ADC_Resolution = ADC_Resolution_12b;
ADC_InitStructure.ADC_ContinuousConvMode = ENABLE;
ADC_InitStructure.ADC_ExternalTrigConvEdge = ADC_ExternalTrigConvEdge_None;
ADC_InitStructure.ADC_DataAlign = ADC_DataAlign_Right;
ADC_InitStructure.ADC_ScanDirection = ADC_ScanDirection_Backward;
ADC_Init(ADC1, &ADC_InitStructure);
/* Convert the ADC1 Channel 1 with 71.5 Cycles as sampling time */
ADC_ChannelConfig(ADC1, ADC_Channel_2 , ADC_SampleTime_71_5Cycles);
/* ADC Calibration */
ADC_GetCalibrationFactor(ADC1);
/* Enable ADC1 */
ADC_Cmd(ADC1, ENABLE);
/* Wait the ADCEN falg */
while(!ADC_GetFlagStatus(ADC1, ADC_FLAG_ADEN));
/* ADC1 regular Software Start Conv */
ADC_StartOfConversion(ADC1);
}
void DMA1_Channel1_IRQHandler()
{
uint8_t i = 0;
if(DMA_GetITStatus(DMA1_IT_TC1) != RESET)
{
DMA_ClearITPendingBit(DMA1_IT_TC1);
for(i=0;i<32;i++)
{
printf("%d\n",(RegularConvData_Tab[i]-2048));
}
}
}
首先貼段程式碼，這是ADC和DMA的初始化函式。上面程式碼實現的功能是ADC取樣之後通過DMA方式把取樣資料放入Memory ，即程式中定義的陣列RegularConvData_Tab[32]。
幾點需要注意的引數：
1、DMA_InitStructure.DMA_MemoryBaseAddr = (uint32_t)RegularConvData_Tab;
2、DMA_InitStructure.DMA_MemoryInc = DMA_MemoryInc_Enable;//因為陣列大小是32，所以選擇MemoryInc
3、DMA_InitStructure.DMA_Mode = DMA_Mode_Circular; ADC_DMARequestModeConfig(ADC1, ADC_DMAMode_Circular);//這兩個函式對DMA的轉換模式設定要一致
4、 ADC_InitStructure.ADC_ContinuousConvMode = ENABLE; //啟動ADC的迴圈轉換模式
5、 ADC_InitStructure.ADC_ExternalTrigConvEdge = ADC_ExternalTrigConvEdge_None;//ADC的觸發方式是軟體觸發，因為Software starts ADC Conversions by setting
ADSTART=1,即ADC_StartOfConversion(ADC1); 所以外部觸發電平上升沿或者下降沿引數設為ADC_ExternalTrigConvEdge_None
6、ADC_ChannelConfig(ADC1, ADC_Channel_2 , ADC_SampleTime_71_5Cycles); //設定ADC的取樣時間
解析：上述設定ADC clock 為3M，GPIOA2作為作為AD取樣的模擬輸入，GPIOA2對映到ADC的Channel2。首先是ADC取樣頻率f0的計算方法，設ADC的轉換時間是T，由以上設定可得T=(71.5+12.5)*ADC clock。又因為ADC_InitStructure.ADC_ContinuousConvMode = ENABLE，使能了ADC迴圈轉換模式。所以f0=1/T=35.7KHz。所以在這種ADC continuousConvMode模式下，改變ADC clock 和ADC 取樣時間，可以得到想要的ADC取樣頻率。但往往由於ADC clock 和 ADC_SampleTime不能很好的配，總得不到想要的任意ADC取樣頻率，於是想到了用TIMER來設定ADC取樣頻率。上述觸發了DMA傳輸完成中斷，在中斷裡列印由ADC取樣後放到數組裡的數值。
用TIMER來控制ADC取樣頻率，我想得到16KHz的ADC取樣頻率，所以我的定時器要設定為62us定時一次。
#define ADC1_TIM_PRESCALER 5
#define ADC1_TIM_CLKDIV 0
#define ADC1_TIM_TIME_US 62
void TIM15_Init(void)
{
__IO uint32_t KEY_TIM_CLKValuekHz = 0; /* Contains the frequency input of KEY_TIM in Khz */
__IO uint16_t TimeIntCount = 0;
TIM_TimeBaseInitTypeDef TIM_TimeBaseStructure;
/* Get frequency input of Decode_TIM in Khz */
KEY_TIM_CLKValuekHz = CM0_TIM_GetCounterCLKValue() / ((ADC1_TIM_PRESCALER + 1)*1000);
/* Calc the TIM count */
TimeIntCount = (KEY_TIM_CLKValuekHz * ADC1_TIM_TIME_US)/1000;
/* Decode_TIM Configuration */
TIM_DeInit(ADC1_TIM);
TIM_TimeBaseStructure.TIM_Period = TimeIntCount;
TIM_TimeBaseStructure.TIM_Prescaler = ADC1_TIM_PRESCALER;
TIM_TimeBaseStructure.TIM_ClockDivision = ADC1_TIM_CLKDIV;
TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;
TIM_TimeBaseInit(ADC1_TIM, (TIM_TimeBaseInitTypeDef *)&TIM_TimeBaseStructure);
/* Clear Decode_TIM Capture compare interrupt pending bit */
TIM_ClearITPendingBit(ADC1_TIM, TIM_IT_Update);
TIM_SelectOutputTrigger(ADC1_TIM,TIM_TRGOSource_Update);
/* Disable Decode_TIM counter */
TIM_Cmd(ADC1_TIM, ENABLE);
}
void ADC1_DMA_Config(void)//PA2
{
ADC_InitTypeDef ADC_InitStructure;
GPIO_InitTypeDef GPIO_InitStructure;
DMA_InitTypeDef DMA_InitStructure;
/* ADC1 DeInit */
ADC_DeInit(ADC1);
/* GPIOA Periph clock enable */
RCC_AHBPeriphClockCmd(RCC_AHBPeriph_GPIOA, ENABLE);
/* ADC1 Periph clock enable */
RCC_APB2PeriphClockCmd(RCC_APB2Periph_ADC1, ENABLE);
/* DMA1 clock enable */
RCC_AHBPeriphClockCmd(RCC_AHBPeriph_DMA1 , ENABLE);
/* Configure ADC Channel2 as analog input */
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_2 ;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AN;
GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_NOPULL ;
GPIO_Init(GPIOA, &GPIO_InitStructure);
/* DMA1 Channel1 Config */
DMA_DeInit(DMA1_Channel1);
DMA_InitStructure.DMA_PeripheralBaseAddr = (uint32_t)ADC1_DR_Address;
DMA_InitStructure.DMA_MemoryBaseAddr = (uint32_t)RegularConvData_Tab;
DMA_InitStructure.DMA_DIR = DMA_DIR_PeripheralSRC;//read from peripheral
DMA_InitStructure.DMA_BufferSize = 32;
DMA_InitStructure.DMA_PeripheralInc = DMA_PeripheralInc_Disable;
DMA_InitStructure.DMA_MemoryInc = DMA_MemoryInc_Enable;
DMA_InitStructure.DMA_PeripheralDataSize = DMA_PeripheralDataSize_HalfWord;
DMA_InitStructure.DMA_MemoryDataSize = DMA_MemoryDataSize_HalfWord;
DMA_InitStructure.DMA_Mode = DMA_Mode_Circular;//DMA_Mode_Circular DMA_Mode_Normal
DMA_InitStructure.DMA_Priority = DMA_Priority_High;
DMA_InitStructure.DMA_M2M = DMA_M2M_Disable;
DMA_Init(DMA1_Channel1, &DMA_InitStructure);
/* DMA1 Channel1 enable */
DMA_Cmd(DMA1_Channel1, ENABLE);
DMA_ITConfig(DMA1_Channel1, DMA_IT_TC, ENABLE);
/* ADC DMA request in circular mode */
ADC_DMARequestModeConfig(ADC1, ADC_DMAMode_Circular);
/* Enable ADC_DMA */
ADC_DMACmd(ADC1, ENABLE);
/* Initialize ADC structure */
ADC_StructInit(&ADC_InitStructure);
/* Configure the ADC1 in continous mode withe a resolutuion equal to 12 bits */
ADC_InitStructure.ADC_Resolution = ADC_Resolution_12b;
ADC_InitStructure.ADC_ContinuousConvMode = DISABLE;
ADC_InitStructure.ADC_ExternalTrigConvEdge = ADC_ExternalTrigConvEdge_Rising;
ADC_InitStructure.ADC_ExternalTrigConv = ADC_ExternalTrigConv_T15_TRGO;
ADC_InitStructure.ADC_DataAlign = ADC_DataAlign_Right;
ADC_InitStructure.ADC_ScanDirection = ADC_ScanDirection_Backward;//from channel 16 to 0
ADC_Init(ADC1, &ADC_InitStructure);
/* Convert the ADC1 Channel 2 with 71.5 Cycles as sampling time PCLK/4*/
ADC_ChannelConfig(ADC1, ADC_Channel_2 , ADC_SampleTime_71_5Cycles);
/* ADC Calibration */
ADC_GetCalibrationFactor(ADC1);
/* Enable ADC1 */
ADC_Cmd(ADC1, ENABLE);
/* Wait the ADCEN falg */
while(!ADC_GetFlagStatus(ADC1, ADC_FLAG_ADEN));
/* ADC1 regular Software Start Conv */
ADC_StartOfConversion(ADC1);
}
解析：上述是由TIMER來控制ADC取樣的設定。首先是timer15的初始化，62.5us定時一次，其中要設定timer的更新事件作為觸發輸出，以此來觸 發 ADC。即TIM_SelectOutputTrigger(ADC1_TIM,TIM_TRGOSource_Update); 函式ADC1_DMA_Config(void)中主要是更改ADC部分，其中有三個引數要改：ADC_InitStructure.ADC_ContinuousConvMode = DISABLE;//將ADC迴圈模式給DISABLE掉，因為由timer觸發就不用使能。否則取樣頻率不對，這一點困了我好長時間ADC_InitStructure.ADC_ExternalTrigConvEdge = ADC_ExternalTrigConvEdge_Rising;//ADC由timer的上升沿觸發， ADC_InitStructure.ADC_ExternalTrigConv = ADC_ExternalTrigConv_T15_TRGO;//設定ADC的觸發源是Timer15，這樣設定之後，每次由timer的更新事件觸發一次ADC，不用設定timer的中斷事件，DMA每傳輸完成一次就觸發DMA傳輸完成中斷，在中斷裡就可以測得32次ADC取樣時間t1,經過示波器抓取波形和計算得到 t1/32=62。
當用DMA方式把ADC取樣值傳到DAC時，即實現DMA從外設到外設的傳輸
void DAC_Config(void)
{
DAC_InitTypeDef DAC_InitStructure;
GPIO_InitTypeDef GPIO_InitStructure;
/* Enable GPIOA clock */
RCC_AHBPeriphClockCmd(RCC_AHBPeriph_GPIOA, ENABLE);
/* Configure PA.04 (DAC_OUT1) in analog mode -------------------------*/
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AN;
GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_NOPULL;
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_4;
GPIO_Init(GPIOA, &GPIO_InitStructure);
/* Enable DAC clock */
RCC_APB1PeriphClockCmd(RCC_APB1Periph_DAC, ENABLE);
/* DAC channel1 Configuration */
DAC_InitStructure.DAC_Trigger = DAC_Trigger_None;
DAC_InitStructure.DAC_OutputBuffer = DAC_OutputBuffer_Enable;
/* DAC Channel1 Init */
DAC_Init(DAC_Channel_1, &DAC_InitStructure);
/* Enable DAC Channel1 */
DAC_Cmd(DAC_Channel_1, ENABLE);
}
void ADC1_DMA_Config(void)//PA2
{
ADC_InitTypeDef ADC_InitStructure;
GPIO_InitTypeDef GPIO_InitStructure;
DMA_InitTypeDef DMA_InitStructure;
/* ADC1 DeInit */
ADC_DeInit(ADC1);
/* GPIOA Periph clock enable */
RCC_AHBPeriphClockCmd(RCC_AHBPeriph_GPIOA, ENABLE);
/* ADC1 Periph clock enable */
RCC_APB2PeriphClockCmd(RCC_APB2Periph_ADC1, ENABLE);
/* DMA1 clock enable */
RCC_AHBPeriphClockCmd(RCC_AHBPeriph_DMA1 , ENABLE);
/* Configure ADC Channel2 as analog input */
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_2 ;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AN;
GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_NOPULL ;
GPIO_Init(GPIOA, &GPIO_InitStructure);
/* DMA1 Channel1 Config */
DMA_DeInit(DMA1_Channel1);
DMA_InitStructure.DMA_PeripheralBaseAddr = (uint32_t)ADC1_DR_Address;
DMA_InitStructure.DMA_MemoryBaseAddr = (uint32_t)(&(DAC->DHR12R1));
DMA_InitStructure.DMA_DIR = DMA_DIR_PeripheralSRC;//read from peripheral
DMA_InitStructure.DMA_BufferSize = 1;
DMA_InitStructure.DMA_PeripheralInc = DMA_PeripheralInc_Disable;
DMA_InitStructure.DMA_MemoryInc = DMA_MemoryInc_Disable;
DMA_InitStructure.DMA_PeripheralDataSize = DMA_PeripheralDataSize_HalfWord;
DMA_InitStructure.DMA_MemoryDataSize = DMA_MemoryDataSize_HalfWord;
DMA_InitStructure.DMA_Mode = DMA_Mode_Circular;//DMA_Mode_Circular DMA_Mode_Normal
DMA_InitStructure.DMA_Priority = DMA_Priority_High;
DMA_InitStructure.DMA_M2M = DMA_M2M_Disable;
DMA_Init(DMA1_Channel1, &DMA_InitStructure);
/* DMA1 Channel1 enable */
DMA_Cmd(DMA1_Channel1, ENABLE);
DMA_ITConfig(DMA1_Channel1, DMA_IT_TC, ENABLE);
/* ADC DMA request in circular mode */
ADC_DMARequestModeConfig(ADC1, ADC_DMAMode_Circular);
/* Enable ADC_DMA */
ADC_DMACmd(ADC1, ENABLE);
/* Initialize ADC structure */
ADC_StructInit(&ADC_InitStructure);
/* Configure the ADC1 in continous mode withe a resolutuion equal to 12 bits */
ADC_InitStructure.ADC_Resolution = ADC_Resolution_12b;
ADC_InitStructure.ADC_ContinuousConvMode = DISABLE;
ADC_InitStructure.ADC_ExternalTrigConvEdge = ADC_ExternalTrigConvEdge_Rising;
ADC_InitStructure.ADC_ExternalTrigConv = ADC_ExternalTrigConv_T15_TRGO;
ADC_InitStructure.ADC_DataAlign = ADC_DataAlign_Right;
ADC_InitStructure.ADC_ScanDirection = ADC_ScanDirection_Backward;
ADC_Init(ADC1, &ADC_InitStructure);
/* Convert the ADC1 Channel 2 with 71.5 Cycles as sampling time PCLK/4*/
ADC_ChannelConfig(ADC1, ADC_Channel_2 , ADC_SampleTime_71_5Cycles);
/* ADC Calibration */
ADC_GetCalibrationFactor(ADC1);
/* Enable ADC1 */
ADC_Cmd(ADC1, ENABLE);
/* Wait the ADCEN falg */
while(!ADC_GetFlagStatus(ADC1, ADC_FLAG_ADEN));
/* ADC1 regular Software Start Conv */
ADC_StartOfConversion(ADC1);
}
上述程式碼是設定GPIOA4作為DAC的輸出引腳，使能DAC的Channel 1。ADC_DMA部分，要改動的是隻是DMA部分，有幾個引數要改動
DMA_InitStructure.DMA_MemoryBaseAddr = (uint32_t)(&(DAC->DHR12R1));
DMA_InitStructure.DMA_MemoryInc = DMA_MemoryInc_Disable;
DMA_InitStructure.DMA_BufferSize = 1;
DMA_InitStructure.DMA_PeripheralDataSize = DMA_PeripheralDataSize_HalfWord;
DMA_InitStructure.DMA_MemoryDataSize = DMA_MemoryDataSize_HalfWord;
解析：因為此時DMA要實現從外設到外設的傳輸，所以將DMA_InitStructure.DMA_MemoryBaseAddr這個引數賦予DAC->DHR12R1暫存器，因為DAC轉換時資料的傳輸方向 是DAC->DHR12R1===>>DHRx===>DAC->DORx==>數模轉換器。因為都是傳到DAC->DHR12R1暫存器，所以DMA_MemoryInc DISABLE。因為這時我觸發了DMA傳 輸完成中斷，設定DMA_BufferSize為1，是想實時知道從ADC傳到DAC->DHR12R1裡的值。還有就是引數DMA_InitStructure.DMA_MemoryDataSize,此時應該賦值
DMA _MemoryDataSize_HalfWord,而不是DMA_PeripheralDataSize_HalfWord。我在除錯中一開始出錯就出在這個引數的設定上。
其他總結：
1、我用的晶片是STMF050X系列，其ADC外部觸發事件有：TIM1_TRGO,TIM2_TRGO,TIM3_TRGO,TIM15_TRGO。
雖然手冊中說只有STMF051X系列才有TIM15， 但是我用TIMER15來設定ADC取樣頻率，仍然能用。
2、雖然STMF050x6 datasheet中沒有講到DAC,但是真正實驗了，F050X6的DAC可以用
3、雖然STMF050x6 datasheet中介紹DMA時沒有說支援peripheral to peripheral ,即實現從外設到外設的傳輸，
但試驗後也是可以實現從ADC到DAC資料傳輸的。
4、ADC取樣頻率的計算，對於上面提到的三種傳輸方式。
方式一：ADC迴圈轉換，將轉換後的資料放入放入Memory ，即程式中定義的陣列。
方式二：ADC轉換由timer控制，將轉換後的資料放入程式中定義的陣列（同上）。
方式三：ADC轉換由timer控制，將轉換後的資料放入DAC的某個暫存器裡。
上面三種方式，關於ADC取樣頻率f的計算就兩種模式，一是方式一的方法：採用AD迴圈轉換方式，那麼在AD配置裡計算的AD轉換時間T就有用了，f=1/T。另外一種就是ADC用timer控制後，迴圈轉換方式被Disable了，那麼此時的f就應該是timer出發時間的倒數了！！！