ADXL345 三轴加速度数据SPI读取、多字节读取、DMA SPI读取和FIFO数据读取

ADXL345 三轴加速度数据SPI读取、多字节读取、DMA SPI读取和FIFO数据读取

1、简介及注意事项

  ADXL345传感器分辨率13位，测量范围±16g（可选±2、±4、±8g），输出数据格式为16位补码，可通过SPI（三线或者四线）或者IIC接口读取。同时还支持32级的FIFO数据存储，满足快速读取数据的要求。

1. 关于初始化
   一般初始化0x31,0x2D,0x2C,0x2F,0x38,0x2E,0x1E,0x1F,0x20这些寄存器即可。关于这些寄存器的说明，具体可以参考手册。
   需要注意的一点是：如果要使用中断进行数据读取，那么初始化之前对中断寄存器清零，所有其他功能初始化完之后，再设置中断使能。

   SpiWriteCmd(0x2E,0x00);       // 中断寄存器清零SpiWriteCmd(0x31,0x0B);       // 4线SPI 全分辨率  g加速度范围SpiWriteCmd(0x2D,0x08);       // 传感器测量模式SpiWriteCmd(0x2C,0x0E);       // 传感器传输数据速率1600HZSpiWriteCmd(0x2F,0x03);       // 中断映射SpiWriteCmd(0x38,0x94);       // FIFO模式设置SpiWriteCmd(0x1E,0x00);       // X轴偏移量SpiWriteCmd(0x1F,0x00);       // Y轴偏移量SpiWriteCmd(0x20,0x00);       // Z轴偏移量SpiWriteCmd(0x2E,0x83);       //中断寄存器使能

2. SPI时钟要求
   在设置读取速率的时候，要和SPI的时钟匹配起来，否则可能读到错误的数据，比如设置1600HZ，SPI时钟要大于2MHZ。SPI读取数据时钟最大5MHZ。
3. SPI总线的理解
   SPI要读取一个数据，必须先写入一个数据。在写入数据的时候，时钟线才会启动。
4. 读写以及多字节读取指令的区别
   
   从上面可以看出，
   读的时候，地址的最高位为1；
   写的时候，地址的最高位为0；
   在进行多字节读取的时候，次高位为1，这样才可以多字节写和读；

2、SPI数据读取

话不多说，直接上代码，本文采用STMF407读取数据，SPI数据位8位，全双工，软件控制片选，高位在前（MB First），

SPI.h#define ADS_SPI_PORT               GPIOB
#define ADS_SPI_CS_PIN             GPIO_Pin_12
#define ADS_SPI_SCK_PIN            GPIO_Pin_13
#define ADS_SPI_MISO_PIN           GPIO_Pin_14
#define ADS_SPI_MOSI_PIN           GPIO_Pin_15#define ADS_SPI_CS_HIGH()          GPIO_SetBits(ADS_SPI_PORT, ADS_SPI_CS_PIN)
#define ADS_SPI_CS_LOW() 	       GPIO_ResetBits(ADS_SPI_PORT, ADS_SPI_CS_PIN)SPI.c
unsigned char ADXL345RXBuff[250];     //DMA 接收缓存
unsigned char ADXL345TXBuff[10];      //DMA 发送缓存// SPI IO口初始化
void Spi2IOInit(void)
{GPIO_InitTypeDef GPIO_InitStructure;// Enable GPIOC clocks RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOB, ENABLE);// Connect SPI2 pins to AF5GPIO_PinAFConfig(ADS_SPI_PORT, GPIO_PinSource13, GPIO_AF_SPI2);  // SCKGPIO_PinAFConfig(ADS_SPI_PORT, GPIO_PinSource14, GPIO_AF_SPI2);  // MISOGPIO_PinAFConfig(ADS_SPI_PORT, GPIO_PinSource15, GPIO_AF_SPI2);  // MOSI// SPI SCK¡¢MOSI pin configurationGPIO_InitStructure.GPIO_Pin = ADS_SPI_SCK_PIN|ADS_SPI_MOSI_PIN|ADS_SPI_MISO_PIN;GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF;GPIO_InitStructure.GPIO_OType = GPIO_OType_PP;GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_NOPULL;//GPIO_PuPd_DOWN;//GPIO_PuPd_UP;//GPIO_PuPd_NOPULL;GPIO_InitStructure.GPIO_Speed = GPIO_Speed_100MHz;GPIO_Init(ADS_SPI_PORT, &GPIO_InitStructure);//SPI2 NSS pin in output pushpull mode GPIO_InitStructure.GPIO_Pin = ADS_SPI_CS_PIN;GPIO_InitStructure.GPIO_Mode = GPIO_Mode_OUT;GPIO_InitStructure.GPIO_OType = GPIO_OType_PP;GPIO_InitStructure.GPIO_Speed = GPIO_Speed_100MHz;GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_NOPULL;  //GPIO_PuPd_NOPULL;GPIO_Init(ADS_SPI_PORT, &GPIO_InitStructure);ADS_SPI_CS_HIGH();  // cs default state is highADS_SPI_CS_LOW(); ADS_SPI_CS_HIGH(); 
}// SPI模式初始化
void SPI2Init(void)
{SPI_InitTypeDef  SPI_InitStructure;NVIC_InitTypeDef NVIC_InitStructure;SPI_I2S_DeInit(SPI2);//Enable the SPI periph RCC_APB1PeriphClockCmd(RCC_APB1Periph_SPI2, ENABLE);Spi2IOInit();// SPI configurationSPI_InitStructure.SPI_Direction = SPI_Direction_2Lines_FullDuplex;SPI_InitStructure.SPI_Mode = SPI_Mode_Master;SPI_InitStructure.SPI_DataSize = SPI_DataSize_8b;SPI_InitStructure.SPI_CPOL = SPI_CPOL_High;SPI_InitStructure.SPI_CPHA = SPI_CPHA_2Edge;  // SPI_CPHA_2Edge;SPI_InitStructure.SPI_NSS = SPI_NSS_Soft;SPI_InitStructure.SPI_BaudRatePrescaler = SPI_BaudRatePrescaler_16;SPI_InitStructure.SPI_FirstBit = SPI_FirstBit_MSB;SPI_InitStructure.SPI_CRCPolynomial = 7;SPI_Init(SPI2, &SPI_InitStructure);// Enable the SPI2SPI_Cmd(SPI2, ENABLE);
}
// SPI写指令
void SpiWriteCmd(u8 cmd,u8 data)
{ADS_SPI_CS_LOW(); while((SPI2->SR &0x0002)==0);  SPI2->DR = (cmd);while((SPI2->SR &0x0001)==0);SPI_I2S_ReceiveData(SPI2); while((SPI2->SR &0x0002)==0);  SPI2->DR = (data);while((SPI2->SR &0x0001)==0);SPI_I2S_ReceiveData(SPI2); ADS_SPI_CS_HIGH();
}
// SPI读指令
u8 SpiReadCmd(u8 cmd)
{ADS_SPI_CS_LOW(); unsigned char returnvalue;while((SPI2->SR &0x0002)==0);  SPI2->DR = (cmd|0x80);while((SPI2->SR &0x0001)==0);returnvalue =  (unsigned char)(SPI_I2S_ReceiveData(SPI2)); // Return the Byte read from the SPI buswhile((SPI2->SR &0x0002)==0);  SPI2->DR = (0x00);while((SPI2->SR &0x0001)==0);returnvalue =(unsigned char)(SPI_I2S_ReceiveData(SPI2)); // Return the Byte read from the SPI busADS_SPI_CS_HIGH();return(returnvalue);  
}void ADXL345Init()
{u8 TempData;SPI2Init();TempData = SpiReadCmd(0x00);while(TempData!=0xE5)     //判断是否器件ID正确 验证SPI通信是否正常{SendData(&TempData,1);}SpiWriteCmd(0x2E,0x00);    SpiWriteCmd(0x31,0x0B);SpiWriteCmd(0x2D,0x08);SpiWriteCmd(0x2C,0x0E);SpiWriteCmd(0x2E,0x00);SpiWriteCmd(0x38,0x00);SpiWriteCmd(0x2F,0x00);SpiWriteCmd(0x1E,0x00);SpiWriteCmd(0x1F,0x00);SpiWriteCmd(0x20,0x00); 
}void ReadADXL345Data()
{unsigned char StrBuff[50];short int Acc_X=0,Acc_Y=0,Acc_Z=0;unsigned char Buf[6];Buf[0]=SpiReadCmd(0x32);Buf[1]=SpiReadCmd(0x33);Buf[2]=SpiReadCmd(0x34);Buf[3]=SpiReadCmd(0x35);Buf[4]=SpiReadCmd(0x36);Buf[5]=SpiReadCmd(0x37);Acc_X = ((Buf[1]<<8|Buf[0]));Acc_Y = ((Buf[3]<<8|Buf[2]));Acc_Z = ((Buf[5]<<8|Buf[4]));sprintf(StrBuff,"X=%4.3f    m/s2   Y=%4.3f   m/s2   Z=%4.3f   m/s2 \r\n",Acc_X*3.9/1000*9.8,Acc_Y*3.9/1000*9.8,Acc_Z*3.9/1000*9.8);SendData(StrBuff,strlen(StrBuff));

读取加速度传感器结果，本文中将g转换成m/s2结果显示。

3、多字节读取

  多字节读取的方式和常规不同的就是：
  无需自己手动修改读取数据的地址，
  外部传感器自动修改地址并传输，
  多字节读取时序图如下：

  从上面可以看出，在发送0xF2之后，无论发送什么数据，都自动传回六个数据。
  有的好奇宝宝可能会问，为什么是0xF2呢？
  因为读指令最高位为1，次高位为多字节位，要置1，而寄存器的数据地址为0x32，这样或则可以得到0xF2。

void ContinuousReadADXL345Data()
{unsigned char StrBuff[50];short int Acc_X=0,Acc_Y=0,Acc_Z=0;unsigned char Buf[6];ADS_SPI_CS_LOW(); unsigned char returnvalue;while((SPI2->SR &0x0002)==0);  SPI2->DR = 0x32|0xC0;while((SPI2->SR &0x0001)==0);Buf[0] =  (unsigned char)(SPI_I2S_ReceiveData(SPI2)); // Return the Byte read from the SPI buswhile((SPI2->SR &0x0002)==0);  SPI2->DR = 0x00;while((SPI2->SR &0x0001)==0);Buf[0] =  (unsigned char)(SPI_I2S_ReceiveData(SPI2)); // Return the Byte read from the SPI bus//	Buf[1] =  (unsigned char)(SPI_I2S_ReceiveData(SPI2));while((SPI2->SR &0x0002)==0);  SPI2->DR = 0x00;while((SPI2->SR &0x0001)==0);Buf[1] =  (unsigned char)(SPI_I2S_ReceiveData(SPI2)); // Return the Byte read from the SPI buswhile((SPI2->SR &0x0002)==0);  SPI2->DR = 0x00;while((SPI2->SR &0x0001)==0);Buf[2] =  (unsigned char)(SPI_I2S_ReceiveData(SPI2)); // Return the Byte read from the SPI buswhile((SPI2->SR &0x0002)==0);  SPI2->DR = 0x00;while((SPI2->SR &0x0001)==0);Buf[3] =  (unsigned char)(SPI_I2S_ReceiveData(SPI2)); // Return the Byte read from the SPI buswhile((SPI2->SR &0x0002)==0);  SPI2->DR = 0x00;while((SPI2->SR &0x0001)==0);Buf[4] =  (unsigned char)(SPI_I2S_ReceiveData(SPI2)); // Return the Byte read from the SPI buswhile((SPI2->SR &0x0002)==0);  SPI2->DR = 0x00;while((SPI2->SR &0x0001)==0);Buf[5] =  (unsigned char)(SPI_I2S_ReceiveData(SPI2)); // Return the Byte read from the SPI busADS_SPI_CS_HIGH();Acc_X = ((Buf[1]<<8|Buf[0]));Acc_Y = ((Buf[3]<<8|Buf[2]));Acc_Z = ((Buf[5]<<8|Buf[4]));sprintf(StrBuff,"X=%4.1f***Y=%4.1f***Z=%4.1f\r\n",Acc_X*3.9/1000*9.8,Acc_Y*3.9/1000*9.8,Acc_Z*3.9/1000*9.8);SendData(StrBuff,strlen(StrBuff));
}

  从上面可以看出，只需填写第一个寄存器的地址之后，后面的数据可以直接读取，无需再修改寄存器。

4、DMA 多字节读取

  使用DMA进行数据读取，在这里我使用数据更新中断去读取数据。
  设置INT1数据更新中断使能，触发外中断去开始DMA数据数据传输。

void SPI2Init(void)
{SPI_InitTypeDef  SPI_InitStructure;NVIC_InitTypeDef NVIC_InitStructure;SPI_I2S_DeInit(SPI2);//Enable the SPI periph RCC_APB1PeriphClockCmd(RCC_APB1Periph_SPI2, ENABLE);Spi2IOInit();// SPI configurationSPI_InitStructure.SPI_Direction = SPI_Direction_2Lines_FullDuplex;SPI_InitStructure.SPI_Mode = SPI_Mode_Master;SPI_InitStructure.SPI_DataSize = SPI_DataSize_8b;SPI_InitStructure.SPI_CPOL = SPI_CPOL_High;SPI_InitStructure.SPI_CPHA = SPI_CPHA_2Edge;  // SPI_CPHA_2Edge;SPI_InitStructure.SPI_NSS = SPI_NSS_Soft;SPI_InitStructure.SPI_BaudRatePrescaler = SPI_BaudRatePrescaler_16;SPI_InitStructure.SPI_FirstBit = SPI_FirstBit_MSB;SPI_InitStructure.SPI_CRCPolynomial = 7;SPI_Init(SPI2, &SPI_InitStructure);// Enable the SPI2SPI_Cmd(SPI2, ENABLE);NVIC_InitStructure.NVIC_IRQChannel = DMA1_Stream3_IRQn;NVIC_InitStructure.NVIC_IRQChannelSubPriority = 0;NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 1;NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;NVIC_Init(&NVIC_InitStructure);NVIC_InitStructure.NVIC_IRQChannel = DMA1_Stream4_IRQn;NVIC_Init(&NVIC_InitStructure);MyDMAInit();   EXTIX_Init();     
}void MyDMAInit()
{DMA_InitTypeDef  DMA_InitStructure;RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_DMA1,ENABLE);//DMA时钟DMA_DeInit(DMA1_Stream3);  //SPI_RX/* DMA Stream 3 */DMA_InitStructure.DMA_Channel = DMA_Channel_0;  //DMA_InitStructure.DMA_PeripheralBaseAddr =(u32)(&(SPI2->DR));·DMA_InitStructure.DMA_Memory0BaseAddr = (u32)(&ADXL345RXBuff[0]);//DMA_InitStructure.DMA_DIR = DMA_DIR_PeripheralToMemory;//DMA_InitStructure.DMA_BufferSize = FIFO_COUNT*7;//DMA_InitStructure.DMA_PeripheralInc = DMA_PeripheralInc_Disable;//DMA_InitStructure.DMA_MemoryInc = DMA_MemoryInc_Enable;//DMA_InitStructure.DMA_PeripheralDataSize = DMA_PeripheralDataSize_Byte;//DMA_InitStructure.DMA_MemoryDataSize = DMA_MemoryDataSize_Byte;//DMA_InitStructure.DMA_Mode = DMA_Mode_Normal;// DMA_InitStructure.DMA_Priority = DMA_Priority_Medium;//DMA_InitStructure.DMA_FIFOMode = DMA_FIFOMode_Disable;         DMA_InitStructure.DMA_FIFOThreshold = DMA_FIFOThreshold_Full;DMA_InitStructure.DMA_MemoryBurst = DMA_MemoryBurst_Single;//DMA_InitStructure.DMA_PeripheralBurst = DMA_PeripheralBurst_Single;//DMA_Init(DMA1_Stream3, &DMA_InitStructure);//³õʼ»¯DMA StreamSPI_I2S_DMACmd(SPI2,SPI_I2S_DMAReq_Rx,ENABLE);DMA_ITConfig(DMA1_Stream3, DMA_IT_TC, ENABLE);DMA_Cmd(DMA1_Stream3, DISABLE);DMA_DeInit(DMA1_Stream4);  //SPI_TX/* DMA Stream 4*/DMA_InitStructure.DMA_Channel = DMA_Channel_0;  //DMA_InitStructure.DMA_PeripheralBaseAddr =(u32)(&(SPI2->DR));//DMA_InitStructure.DMA_Memory0BaseAddr = (u32)(&ADXL345TXBuff[0]);//DMADMA_InitStructure.DMA_DIR = DMA_DIR_MemoryToPeripheral;//DMA_InitStructure.DMA_BufferSize = 7;//DMA_InitStructure.DMA_PeripheralInc = DMA_PeripheralInc_Disable;//DMA_InitStructure.DMA_MemoryInc = DMA_MemoryInc_Enable;//DMA_InitStructure.DMA_PeripheralDataSize = DMA_PeripheralDataSize_Byte;//DMA_InitStructure.DMA_MemoryDataSize = DMA_MemoryDataSize_Byte;//DMA_InitStructure.DMA_Mode = DMA_Mode_Normal;// DMA_InitStructure.DMA_Priority = DMA_Priority_Medium;//DMA_InitStructure.DMA_FIFOMode = DMA_FIFOMode_Disable;         DMA_InitStructure.DMA_FIFOThreshold = DMA_FIFOThreshold_Full;DMA_InitStructure.DMA_MemoryBurst = DMA_MemoryBurst_Single;//DMA_InitStructure.DMA_PeripheralBurst = DMA_PeripheralBurst_Single;//DMA_Init(DMA1_Stream4, &DMA_InitStructure);//SPI_I2S_DMACmd(SPI2,SPI_I2S_DMAReq_Tx,ENABLE);//  DMA_ITConfig(DMA1_Stream4, DMA_IT_TC, ENABLE);
}void EXTIX_Init()
{NVIC_InitTypeDef   NVIC_InitStructure;EXTI_InitTypeDef   EXTI_InitStructure;GPIO_InitTypeDef GPIO_InitStructure;RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOD, ENABLE);RCC_APB2PeriphClockCmd(RCC_APB2Periph_SYSCFG, ENABLE);//GPIO_InitStructure.GPIO_Pin = GPIO_Pin_8;GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IN;GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_NOPULL;//GPIO_PuPd_DOWN;//GPIO_PuPd_UP;//GPIO_PuPd_NOPULL;GPIO_InitStructure.GPIO_Speed = GPIO_Speed_100MHz;GPIO_Init(GPIOD, &GPIO_InitStructure);SYSCFG_EXTILineConfig(EXTI_PortSourceGPIOD, EXTI_PinSource8);//EXTI_InitStructure.EXTI_Line = EXTI_Line8;//LINE8EXTI_InitStructure.EXTI_Mode = EXTI_Mode_Interrupt;//EXTI_InitStructure.EXTI_Trigger = EXTI_Trigger_Rising; //EXTI_InitStructure.EXTI_LineCmd = ENABLE;//EXTI_Init(&EXTI_InitStructure);//NVIC_InitStructure.NVIC_IRQChannel = EXTI9_5_IRQn;//NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 0x01;//NVIC_InitStructure.NVIC_IRQChannelSubPriority = 0x02;//NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;//NVIC_Init(&NVIC_InitStructure);
}u8 ExtiFlag=0;     // 数据更新中断标志位
void EXTI9_5_IRQHandler()
{if(EXTI_GetITStatus(EXTI_Line8)){DMA_Cmd(DMA1_Stream3, DISABLE); DMA_Cmd(DMA1_Stream4, DISABLE); u8 TempData = SpiReadCmd(0x30);if((TempData&0x80))ExtiFlag=1;EXTI_ClearITPendingBit(EXTI_Line8);}
}void SPIDMAReadADXL345Data()
{int pro=0;ADS_SPI_CS_LOW(); DMA_Cmd(DMA1_Stream3, ENABLE);ADXL345TXBuff[0]=0xF2;ADXL345TXBuff[1]=0x00;ADXL345TXBuff[2]=0x00;ADXL345TXBuff[3]=0x00;ADXL345TXBuff[4]=0x00;ADXL345TXBuff[5]=0x00;ADXL345TXBuff[6]=0x00;DMA_Cmd(DMA1_Stream4, DISABLE); DMA_SetCurrDataCounter(DMA1_Stream4,7);          DMA_Cmd(DMA1_Stream4, ENABLE);while(DMA_GetFlagStatus(DMA1_Stream4, DMA_FLAG_TCIF4) == RESET){pro=DMA_GetCurrDataCounter(DMA1_Stream4);}DMA_ClearFlag(DMA1_Stream4, DMA_FLAG_TCIF4);while(SPI_I2S_GetFlagStatus(SPI2,SPI_I2S_FLAG_BSY)==SET);       //需要等待SPI总线传输完成最后一个字节，否则Z轴数据存在问题。ADS_SPI_CS_HIGH();ExtiFlag=0;
}u8 DMAReadFlag = 0;                   // DMA接收数据完成中断标志位
void DMA1_Stream3_IRQHandler()
{if (DMA_GetITStatus(DMA1_Stream3, DMA_IT_TCIF3) != RESET){DMA_ClearFlag(DMA1_Stream3, DMA_IT_TCIF3);DMAReadFlag=1;DMA_Cmd(DMA1_Stream3, DISABLE);}
}void ReadDMAData()
{short int Acc_X=0,Acc_Y=0,Acc_Z=0;unsigned char StrBuff[50];if(ExtiFlag==1)                       //数据更新中断，则开始DMA读取数据{SPIDMAReadADXL345Data();}if(DMAReadFlag)                        //读取数据完成之后，则开始计算三轴并显示{Acc_X = ((ADXL345RXBuff[2]<<8|ADXL345RXBuff[1]));Acc_Y = ((ADXL345RXBuff[4]<<8|ADXL345RXBuff[3]));Acc_Z = ((ADXL345RXBuff[6]<<8|ADXL345RXBuff[5]));sprintf(StrBuff,"X=%4.3f    Y=%4.3f     Z=%4.3f\r\n",Acc_X*3.9/1000*9.8,Acc_Y*3.9/1000*9.8,Acc_Z*3.9/1000*9.8);SendData(StrBuff,strlen(StrBuff));DMAReadFlag=0;}
}

5、DMA FIFO数据读取

  FIFO模式共分为三种，FIFO模式，流模式和触发模式，一般使用前两种，FIFO模式存满缓存区之后则不再继续填充数据，而流模式则继续回覆盖之前已存在的数据。
  FIFO最大缓存32级数据，即32个三轴数据，总共32*6=192个数据。FIFO可设置存满一定字节后触发中断，中断为水印中断（Watermark 奇怪的名字）。存满之后继续填充缓存器，直到存满32级缓存。所以不需要完全存满再去读取数据，那样时效性不高，可设置16级之后就读取数据，这样类似于半中断，效率更高。
  这个FIFO唯一一点不好的地方我觉得是，FIFO数据不是一次性读出，而是多次通过寄存器去读取，意思就是FIFO数据的读取地址就是0x32-0x37，读完之后，FIFO缓存就往寄存器里填充缓存的数据，然后再去读，直到填充完。
  使用水印中断来触发外中断去读取FIFO数据。

void ADXL345Init()
{u8 TempData;SPI2Init();TempData = SpiReadCmd(0x00);while(TempData!=0xE5){SendData(&TempData,1);}SpiWriteCmd(0x2E,0x00);       SpiWriteCmd(0x31,0x0B);      SpiWriteCmd(0x2D,0x08);      SpiWriteCmd(0x2C,0x0E);      SpiWriteCmd(0x2F,0x03);       SpiWriteCmd(0x38,0x9F);       // 设置FIFO模式   10011111   32条目  流模式   只保存最新数据SpiWriteCmd(0x1E,0x00);      SpiWriteCmd(0x1F,0x00);       SpiWriteCmd(0x20,0x00);      SpiWriteCmd(0x2E,0x83);       //设置INT2 为水印中断ADXL345TXBuff[0]=0xF2;        //DMA 发送缓存ADXL345TXBuff[1]=0x00;ADXL345TXBuff[2]=0x00;ADXL345TXBuff[3]=0x00;ADXL345TXBuff[4]=0x00;ADXL345TXBuff[5]=0x00;ADXL345TXBuff[6]=0x00;
}u8 ExtiFlag=0;
void EXTI9_5_IRQHandler()
{if(EXTI_GetITStatus(EXTI_Line8)){DMA_Cmd(DMA1_Stream3, DISABLE); DMA_Cmd(DMA1_Stream4, DISABLE); u8 TempData = SpiReadCmd(0x30);    //读取中断标志位   确定中断产生if((TempData&0x02))ExtiFlag=1;EXTI_ClearITPendingBit(EXTI_Line8);}
}void SPIDMAReadADXL345Data()
{u8 i=0;DMA_Cmd(DMA1_Stream3, ENABLE);for(i=0;i<FIFO_COUNT;i++)       //FIFO_COUNT  代表触发FIFO缓存个数{ADS_SPI_CS_LOW(); DMA_Cmd(DMA1_Stream4, DISABLE); DMA_SetCurrDataCounter(DMA1_Stream4,7);          /DMA_Cmd(DMA1_Stream4, ENABLE);while(DMA_GetFlagStatus(DMA1_Stream4, DMA_FLAG_TCIF4) == RESET){DMA_GetCurrDataCounter(DMA1_Stream4);//}DMA_ClearFlag(DMA1_Stream4, DMA_FLAG_TCIF4);while(SPI_I2S_GetFlagStatus(SPI2,SPI_I2S_FLAG_BSY)==SET);ADS_SPI_CS_HIGH();}ExtiFlag=0;
}u8 DMAReadFlag = 0;
void DMA1_Stream3_IRQHandler()
{if (DMA_GetITStatus(DMA1_Stream3, DMA_IT_TCIF3) != RESET){DMA_ClearFlag(DMA1_Stream3, DMA_IT_TCIF3);DMAReadFlag=1;DMA_Cmd(DMA1_Stream3, DISABLE);}
}void ReadDMAData()
{short int Acc_X=0,Acc_Y=0,Acc_Z=0;unsigned char StrBuff[50];unsigned char C=10;    if(ExtiFlag==1)     {SPIDMAReadADXL345Data();      }if(DMAReadFlag)                 {Acc_X = ((ADXL345RXBuff[7*C+2]<<8|ADXL345RXBuff[7*C+1]));Acc_Y = ((ADXL345RXBuff[7*C+4]<<8|ADXL345RXBuff[7*C+3]));Acc_Z = ((ADXL345RXBuff[7*C+6]<<8|ADXL345RXBuff[7*C+5]));sprintf((char *)StrBuff,"X=%4.3f    Y=%4.3f     Z=%4.3f\r\n",Acc_X*3.9/1000*9.8,Acc_Y*3.9/1000*9.8,Acc_Z*3.9/1000*9.8);SendData(StrBuff,strlen((char *)StrBuff));DMAReadFlag=0;}
}

  最后楼主分享一个完整的代码，使用STM32F407读取ADXL345三轴加速度传感器数据，keil工程。
下载链接：
工程文件 SPI协议版本
工程文件 SPI+DMA协议版本

如有雷同，纯属我抄你，有问题可以直接联系邮箱，在个人资料里面。

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