STM32F407 ADC+DMA+定时器 定时采样模拟量
文章目录
前言
项目中需要对多个通道的电压进行一定频率的AD采样，由于采样过程贯穿整个任务，为了使采样过程尽可能不占用CPU资源，采用定时器触发的多通道ADC扫描采样，且采样数据由DMA传到RAM中的缓存。
这样做有以下几个好处：1、由定时器触发ADC采样，这样采样的频率可控，且定时器触发不会占用任何CPU资源；2、DMA进一步降低了任务对CPU的占有率。
提示：以下是本篇文章正文内容，下面案例可供参考
一、硬件原理
1.1 ADC
STM32F 407的ADC的规则通道扫描采样，配置好规则通道后，可以采用软件触发的方式开启AD转换，也可通过外部触发，如下图所示。可以通过定时器以及外部中断方式触发:
如下图为ADC 内部使用框图:
1.2 定时器
如上图所示是定时器的内部硬件原理框图,在此使用定时器的TIMER3 的TRGO信号作为ADC转换的触发信号,当接收到一次中断信号后,ADC通道进行转换一次.
3. DMA
如上图所示,ADC1 使用的是DMA 的stream0 数据流,ADC2使用DMA2 的Stream2数据流.
二、代码实现
2.1初始化
global 数据
__IO uint16_t g_Adc2ConvertedValues[10][6];//6 个通道每个通道采样10次
2.1.1 PIN initial
static void BspGpioConfig(void)
{
GPIO_InitTypeDef GPIO_InitStructure;
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_0
| GPIO_Pin_4
| GPIO_Pin_7;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AN;
GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_NOPULL;
GPIO_Init(GPIOA, &GPIO_InitStructure);
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_0
| GPIO_Pin_1;
GPIO_Init(GPIOB, &GPIO_InitStructure);
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_0
| GPIO_Pin_1 ;
GPIO_Init(GPIOC, &GPIO_InitStructure);
return;
}
2.2 ADC 初始化 代码
static void BspAdcConfig(void)
{
ADC_CommonInitTypeDef ADC_CommonInitStructure;
ADC_InitTypeDef ADC_InitStructure;
ADC_CommonInitStructure.ADC_Mode = ADC_Mode_Independent;
ADC_CommonInitStructure.ADC_Prescaler = ADC_Prescaler_Div8;
ADC_CommonInitStructure.ADC_DMAAccessMode = ADC_DMAAccessMode_Disabled;
ADC_CommonInitStructure.ADC_TwoSamplingDelay = ADC_TwoSamplingDelay_20Cycles;
ADC_CommonInit(&ADC_CommonInitStructure);
ADC_InitStructure.ADC_Resolution = ADC_Resolution_12b;
ADC_InitStructure.ADC_ScanConvMode = DISABLE;
ADC_InitStructure.ADC_ContinuousConvMode = DISABLE;
ADC_InitStructure.ADC_ExternalTrigConvEdge = ADC_ExternalTrigConvEdge_Rising;
ADC_InitStructure.ADC_ExternalTrigConv = ADC_ExternalTrigConv_T2_TRGO;
ADC_InitStructure.ADC_DataAlign = ADC_DataAlign_Right;
ADC_InitStructure.ADC_NbrOfConversion = 1;
ADC_Init(ADC1, &ADC_InitStructure);
ADC_RegularChannelConfig(ADC1, ADC_Channel_0, 1, ADC_SampleTime_480Cycles); // PA0_AD0_AC
ADC_DMARequestAfterLastTransferCmd(ADC1, ENABLE);
ADC_DMACmd(ADC1, ENABLE);
ADC_Cmd(ADC1, ENABLE);
ADC_InitStructure.ADC_ScanConvMode = ENABLE;
ADC_InitStructure.ADC_ExternalTrigConv = ADC_ExternalTrigConv_T3_TRGO;
ADC_InitStructure.ADC_NbrOfConversion = ADC2_NbrofChannel;
ADC_Init(ADC2, &ADC_InitStructure);
ADC_RegularChannelConfig(ADC2, ADC_Channel_4, 1, ADC_SampleTime_480Cycles); // PA4_AD4_24V_2
ADC_RegularChannelConfig(ADC2, ADC_Channel_7, 2, ADC_SampleTime_480Cycles); // PA7_AD7_GNDF
ADC_RegularChannelConfig(ADC2, ADC_Channel_8, 3, ADC_SampleTime_480Cycles); // PB0_AD8_24V_OCP_C1
ADC_RegularChannelConfig(ADC2, ADC_Channel_9, 4, ADC_SampleTime_480Cycles); // PB1_AD9_24V_OCP_C2
ADC_RegularChannelConfig(ADC2, ADC_Channel_10,5, ADC_SampleTime_480Cycles); // PC0_AD10_HOUSING
ADC_RegularChannelConfig(ADC2, ADC_Channel_11,6, ADC_SampleTime_480Cycles); // PC1_AD11_24V_1
ADC_DMARequestAfterLastTransferCmd(ADC2, ENABLE);
ADC_DMACmd(ADC2, ENABLE);
ADC_Cmd(ADC2, ENABLE);
return;
}
2.3 DMA 初始化 代码
static void BspDmaConfig(void)
{
DMA_InitTypeDef DMA_InitStructure;
DMA_InitStructure.DMA_Channel = DMA_Channel_0;
DMA_InitStructure.DMA_PeripheralBaseAddr = (uint32_t)&ADC1->DR;
DMA_InitStructure.DMA_Memory0BaseAddr = (uint32_t)&g_Adc1ConvertedValues;
DMA_InitStructure.DMA_DIR = DMA_DIR_PeripheralToMemory;
DMA_InitStructure.DMA_BufferSize = 1024 * 2;
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_FIFOMode = DMA_FIFOMode_Disable;
DMA_InitStructure.DMA_FIFOThreshold = DMA_FIFOThreshold_HalfFull;
DMA_InitStructure.DMA_MemoryBurst = DMA_MemoryBurst_Single;
DMA_InitStructure.DMA_PeripheralBurst = DMA_PeripheralBurst_Single;
DMA_Init(DMA2_Stream0, &DMA_InitStructure);
DMA_ITConfig(DMA2_Stream0, DMA_IT_HT | DMA_IT_TC, ENABLE);
DMA_Cmd(DMA2_Stream0, ENABLE);
DMA_InitStructure.DMA_Channel = DMA_Channel_1;
DMA_InitStructure.DMA_PeripheralBaseAddr = (uint32_t)&ADC2->DR;
DMA_InitStructure.DMA_Memory0BaseAddr = (uint32_t)&g_Adc2ConvertedValues;
DMA_InitStructure.DMA_BufferSize = ADC2_NbrofChannel * SamplingNumber;//N*M N: channel number M:sampling number
DMA_Init(DMA2_Stream2, &DMA_InitStructure);
DMA_Cmd(DMA2_Stream2, ENABLE);
return;
}
static void BspNvicConfig(void)
{
NVIC_InitTypeDef NVIC_InitStructure;
NVIC_InitStructure.NVIC_IRQChannel = DMA2_Stream0_IRQn;
NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 0;
NVIC_InitStructure.NVIC_IRQChannelSubPriority = 0;
NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
NVIC_Init(&NVIC_InitStructure);
return;
}
在调用这几个函数之前必须设置RCC时钟如下代码设置RCC时钟:
static void BspRccConfig(void)
{
RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOA
| RCC_AHB1Periph_GPIOB
| RCC_AHB1Periph_GPIOC
| RCC_AHB1Periph_DMA2, ENABLE);
RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM2
| RCC_APB1Periph_TIM3, ENABLE);
RCC_APB2PeriphClockCmd(RCC_APB2Periph_ADC1
| RCC_APB2Periph_ADC2, ENABLE);
return;
}
3.1 定时器初始化
static void BspTimConfig(void)
{
TIM_TimeBaseInitTypeDef TIM_TimeBaseStructure;
// TIM2设置ADC1 1024Hz
TIM_TimeBaseStructure.TIM_Prescaler = 0;
TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;
TIM_TimeBaseStructure.TIM_Period = 84000000 / 1024 - 1;
TIM_TimeBaseStructure.TIM_ClockDivision = TIM_CKD_DIV1;
TIM_TimeBaseInit(TIM2, &TIM_TimeBaseStructure);
TIM_SelectOutputTrigger(TIM2, TIM_TRGOSource_Update);
// TIM3设置ADC2 1000Hz
TIM_TimeBaseStructure.TIM_Prescaler = 84000000 / 1000000 - 1;
TIM_TimeBaseStructure.TIM_Period = 1000000 / 1000 - 1;
TIM_TimeBaseInit(TIM3, &TIM_TimeBaseStructure);
TIM_SelectOutputTrigger(TIM3, TIM_TRGOSource_Update);
TIM_Cmd(TIM2, ENABLE);
TIM_Cmd(TIM3, ENABLE);
return;
}
3.2 函数调用
void BspAdcInit(void)
{
BspRccConfig();
BspGpioConfig();
BspAdcConfig();
BspDmaConfig();
BspNvicConfig();
BspTimConfig();
return;
}
在调用BspAdcInit()函数后,就配置完成了ADC+DMA+TIMER的配置.会定时完成采集,且不占用CPU资源.采集的数据将会自动存储在定义的g_Adc2ConvertedValues 全局变量中.
总结
以上流程就是使用STM32的ADC+DMA+timer实现自动定时采样模拟电压的配置使用流程,若读者发先任何疑问,妄指出问题…