1、实验目的
1）使用 TIM1 触发 ADC，ADC 采集的数据通过DMA 传至内存，然后通过串口打印出采集的数据；
2）学会 DMA 传输数据并将数据进行保存；
3）验证ADC 的采样率与实际设置的是否相符。
2、硬件资源
1）指示灯
2）ADC
3）DMA
4）TIM
5）杜邦线
3、软件设计
- void Adc_Configuration(void)
- {
- DMA_InitTypeDef DMA_InitStructure;
- ADC_InitTypeDef ADC_InitStructure;
- GPIO_InitTypeDef GPIO_InitStructure;
- RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOC | RCC_APB2Periph_AFIO, ENABLE);
- GPIO_InitStructure.GPIO_Pin = GPIO_Pin_0;
- GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AIN;
- GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
- GPIO_Init(GPIOC, &GPIO_InitStructure);
- /* Enable DMA1 clock */
- RCC_AHBPeriphClockCmd(RCC_AHBPeriph_DMA1, ENABLE);
- DMA_DeInit(DMA1_Channel1); /* 复位DMA1寄存器到缺省状态 */
- DMA_InitStructure.DMA_PeripheralBaseAddr = ADC1_DR_Address; /* 选择ADC1的数据寄存器作为源 */
- DMA_InitStructure.DMA_MemoryBaseAddr = (uint32_t)&ADC_Sample.Ch1Buf; /* 目标地址 */
- DMA_InitStructure.DMA_DIR = DMA_DIR_PeripheralSRC; /* 设置DMA传输方向，外设(ADC)作为源 */
- DMA_InitStructure.DMA_BufferSize = SAMPLE_COUNT; /* 设置缓冲区大小 */
- DMA_InitStructure.DMA_PeripheralInc = DMA_PeripheralInc_Disable; /* 外设地址不自增 */
- DMA_InitStructure.DMA_MemoryInc = DMA_MemoryInc_Enable; /* 存储器地址需要自增 */
- DMA_InitStructure.DMA_PeripheralDataSize = DMA_PeripheralDataSize_HalfWord; /* 选择外设传输单位：16bit */
- DMA_InitStructure.DMA_MemoryDataSize = DMA_MemoryDataSize_HalfWord; /* 选择内存传输单位：16bit */
- DMA_InitStructure.DMA_Mode = DMA_Mode_Normal; /* 无需循环模式 */
- DMA_InitStructure.DMA_Priority = DMA_Priority_High; /* 选择DMA优先级 */
- DMA_InitStructure.DMA_M2M = DMA_M2M_Disable; /* DMA传输类型，不是内存到内存 */
- DMA_Init(DMA1_Channel1, &DMA_InitStructure);
- /* Enable DMA1 channel1 */
- DMA_Cmd(DMA1_Channel1, ENABLE);
- /* 配置ADC1 */
- /* ADCCLK = PCLK2/2 */
- RCC_ADCCLKConfig(RCC_PCLK2_Div2); /* ADCCLK = PCLK2/2 = 36MHz */
- RCC_APB2PeriphClockCmd(RCC_APB2Periph_ADC1, ENABLE);
- ADC_InitStructure.ADC_Mode = ADC_Mode_Independent;
- ADC_InitStructure.ADC_ScanConvMode = DISABLE;
- ADC_InitStructure.ADC_ContinuousConvMode = DISABLE; /* 连续转换静止 */
- ADC_InitStructure.ADC_ExternalTrigConv = ADC_ExternalTrigConv_T1_CC3; /* 选择TIM1的CC3做触发 */
- ADC_InitStructure.ADC_DataAlign = ADC_DataAlign_Right; /* 数据右对齐,高位为0 */
- ADC_InitStructure.ADC_NbrOfChannel = 1; /* 1个通道 */
- ADC_Init(ADC1, &ADC_InitStructure);
- /* ADC1 regular channels configuration */
- ADC_RegularChannelConfig(ADC1, ADC_Channel_10, 1, ADC_SampleTime_1Cycles5);
- /* Enable ADC1 external trigger conversion */
- ADC_ExternalTrigConvCmd(ADC1, ENABLE);
- /* 使能 ADC1 */
- ADC_Cmd(ADC1, ENABLE);
- /* Enable ADC1 DMA */
- ADC_DMACmd(ADC1, ENABLE);
- /* 使能 ADC1 复位校准寄存器 */
- ADC_ResetCalibration(ADC1);
- /* 检测复位校准寄存器 */
- while(ADC_GetResetCalibrationStatus(ADC1));
- /* 开始 ADC1 校准 */
- ADC_StartCalibration(ADC1);
- /* 等待校准结束 */
- while(ADC_GetCalibrationStatus(ADC1));
- /* 配置采样触发定时器，使用TIM1 CC1 */
- ADC_SampleRate(ADC_Sample.SampleFreq); /* 修改采样频率 */
- }
- /*
- * Function Name : ADC_SampleRate
- * Description : 修改ADC的采样频率
- * Input : - freq: 采样频率 单位Hz
- * Output : None
- * Return : None
- * Attention : None
- */
- void ADC_SampleRate(uint32_t freq)
- {
- /* 配置定时器1第3通道CC3作为ADC1的触发源 */
- uint16_t Period;
- TIM_OCInitTypeDef TIM_OCInitStructure;
- TIM_TimeBaseInitTypeDef TIM_TimeBaseStructure;
- TIM_Cmd(TIM1, DISABLE);
- /* 采样频率计算公式 : period = 72000000 / freq ; 1200 == 60KHz 采样频率 */
- Period = 72000000 / freq;
- /* Enable TIM1 clock */
- RCC_APB2PeriphClockCmd(RCC_APB2Periph_TIM1, ENABLE);
- TIM_TimeBaseStructInit(&TIM_TimeBaseStructure);
- TIM_TimeBaseStructure.TIM_Period = Period;
- TIM_TimeBaseStructure.TIM_Prescaler = 0; /* 计数频率 = 72000 000 / 18 = 4000 000 */
- TIM_TimeBaseStructure.TIM_ClockDivision = 0x0;
- TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;
- TIM_TimeBaseInit(TIM1, &TIM_TimeBaseStructure);
- /* TIM1 channel1 configuration in PWM mode */
- TIM_OCInitStructure.TIM_OCMode = TIM_OCMode_PWM1;
- TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable;
- TIM_OCInitStructure.TIM_Pulse = TIM_TimeBaseStructure.TIM_Period / 2;
- TIM_OCInitStructure.TIM_OCPolarity = TIM_OCPolarity_Low;
- TIM_OC3Init(TIM1, &TIM_OCInitStructure);
- /* TIM1 counter enable */
- TIM_Cmd(TIM1, ENABLE);
- /* TIM1 main Output Enable */
- TIM_CtrlPWMOutputs(TIM1, ENABLE);
- }
采样率的确定：
由两部分组成：ADC 转换时间 + 定时器的触发需要的时间
4、验证