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（出处：http://ezchina.analog.com/thread/7359）

一、硬件电路接口图片

1.ADXL345硬件接口图片使用的是SPI端口进行通信，这样读取数据比较快且后续也可以转化为IIC通信接口。

在网上找一些发现IIC接口的比较多，所以本人就DIY做SPI的通信。

2.STM32F103T系列单片机作为MCU资源比较丰富、本人比较熟悉开发速度较快

硬件电路首先是为了实现功能，所以设计比较简单。后续小编想做无线蓝牙的数据传输，所以硬件上也留了蓝牙串口通信的硬件接口和3.3V电源管理。

暂且将硬件这样设计，设计为双层PCB 这样减少了空间。电容、电阻为0805的易焊接。器件都选为贴片。

二、单片机驱动代码

1.ADXL345的端口配置函数

#define ADXL345_FLAG_TIMEOUT ((uint32_t)0x1000)

#define ADXL345_SPI SPI1

#define ADXL345_SPI_CLK RCC_APB2Periph_SPI1

#define ADXL345_SPI_SCK_PIN GPIO_Pin_5

#define ADXL345_SPI_SCK_GPIO_PORT GPIOA

#define ADXL345_SPI_SCK_GPIO_CLK RCC_APB2Periph_GPIOA

#define ADXL345_SPI_SCK_SOURCE GPIO_PinSource5

#define ADXL345_SPI_SCK_AF GPIO_AF_5

#define ADXL345_SPI_MISO_PIN GPIO_Pin_6

#define ADXL345_SPI_MISO_GPIO_PORT GPIOA

#define ADXL345_SPI_MISO_GPIO_CLK RCC_APB2Periph_GPIOA

#define ADXL345_SPI_MISO_SOURCE GPIO_PinSource6

#define ADXL345_SPI_MISO_AF GPIO_AF_5

#define ADXL345_SPI_MOSI_PIN GPIO_Pin_7

#define ADXL345_SPI_MOSI_GPIO_PORT GPIOA

#define ADXL345_SPI_MOSI_GPIO_CLK RCC_APB2Periph_GPIOA

#define ADXL345_SPI_MOSI_SOURCE GPIO_PinSource7

#define ADXL345_SPI_MOSI_AF GPIO_AF_5

#define ADXL345_SPI_CS_PIN GPIO_Pin_2

#define ADXL345_SPI_CS_GPIO_PORT GPIOB

#define ADXL345_SPI_CS_GPIO_CLK RCC_APB2Periph_GPIOB

#define ADXL345_SPI_INT1_PIN GPIO_Pin_0

#define ADXL345_SPI_INT1_GPIO_PORT GPIOB

#define ADXL345_SPI_INT1_GPIO_CLK RCC_APB2Periph_GPIOB

#define ADXL345_SPI_INT1_EXTI_LINE EXTI_Line0

#define ADXL345_SPI_INT1_EXTI_PORT_SOURCE EXTI_PortSourceGPIOB

#define ADXL345_SPI_INT1_EXTI_PIN_SOURCE EXTI_PinSource0

#define ADXL345_SPI_INT1_EXTI_IRQn EXTI0_IRQn

#define ADXL345_SPI_INT2_PIN GPIO_Pin_1

#define ADXL345_SPI_INT2_GPIO_PORT GPIOB

#define ADXL345_SPI_INT2_GPIO_CLK RCC_APB2Periph_GPIOB

#define ADXL345_SPI_INT2_EXTI_LINE EXTI_Line1

#define ADXL345_SPI_INT2_EXTI_PORT_SOURCE EXTI_PortSourceGPIOB

#define ADXL345_SPI_INT2_EXTI_PIN_SOURCE EXTI_PinSource1

#define ADXL345_SPI_INT2_EXTI_IRQn EXTI1_IRQn

#define ADXL345_WHO_AM_I_ADDR 0x0F

#define ADXL345_CTRL_REG1_ADDR 0x20

#define ADXL345_CTRL_REG2_ADDR 0x21

#define ADXL345_CTRL_REG3_ADDR 0x22

#define ADXL345_CTRL_REG4_ADDR 0x23

#define ADXL345_CTRL_REG5_ADDR 0x24

#define ADXL345_REFERENCE_REG_ADDR 0x25

#define ADXL345_OUT_TEMP_ADDR 0x26

#define ADXL345_STATUS_REG_ADDR 0x27

#define ADXL345_OUT_X_L_ADDR 0x28

#define ADXL345_OUT_X_H_ADDR 0x29

#define ADXL345_OUT_Y_L_ADDR 0x2A

#define ADXL345_OUT_Y_H_ADDR 0x2B

#define ADXL345_OUT_Z_L_ADDR 0x2C

#define ADXL345_OUT_Z_H_ADDR 0x2D

#define ADXL345_FIFO_CTRL_REG_ADDR 0x2E

#define ADXL345_FIFO_SRC_REG_ADDR 0x2F

#define ADXL345_INT1_CFG_ADDR 0x30

#define ADXL345_INT1_SRC_ADDR 0x31

#define ADXL345_INT1_TSH_XH_ADDR 0x32

#define ADXL345_INT1_TSH_XL_ADDR 0x33

#define ADXL345_INT1_TSH_YH_ADDR 0x34

#define ADXL345_INT1_TSH_YL_ADDR 0x35

#define ADXL345_INT1_TSH_ZH_ADDR 0x36

#define ADXL345_INT1_TSH_ZL_ADDR 0x37

#define ADXL345_INT1_DURATION_ADDR 0x38

#define I_AM_ADXL345 ((uint8_t)0xD4)

#define ADXL345_MODE_POWERDOWN ((uint8_t)0x00)

#define ADXL345_MODE_ACTIVE ((uint8_t)0x08)

#define ADXL345_OUTPUT_DATARATE_1 ((uint8_t)0x00)

#define ADXL345_OUTPUT_DATARATE_2 ((uint8_t)0x40)

#define ADXL345_OUTPUT_DATARATE_3 ((uint8_t)0x80)

#define ADXL345_OUTPUT_DATARATE_4 ((uint8_t)0xC0)

#define ADXL345_X_ENABLE ((uint8_t)0x02)

#define ADXL345_Y_ENABLE ((uint8_t)0x01)

#define ADXL345_Z_ENABLE ((uint8_t)0x04)

#define ADXL345_AXES_ENABLE ((uint8_t)0x07)

#define ADXL345_AXES_DISABLE ((uint8_t)0x00)

#define ADXL345_BANDWIDTH_1 ((uint8_t)0x00)

#define ADXL345_BANDWIDTH_2 ((uint8_t)0x10)

#define ADXL345_BANDWIDTH_3 ((uint8_t)0x20)

#define ADXL345_BANDWIDTH_4 ((uint8_t)0x30)

#define ADXL345_FULLSCALE_250 ((uint8_t)0x00)

#define ADXL345_FULLSCALE_500 ((uint8_t)0x10)

#define ADXL345_FULLSCALE_2000 ((uint8_t)0x20)

#define ADXL345_BlockDataUpdate_Continous ((uint8_t)0x00)

#define ADXL345_BlockDataUpdate_Single ((uint8_t)0x80)

#define ADXL345_BLE_LSB ((uint8_t)0x00)

#define ADXL345_BLE_MSB ((uint8_t)0x40)

#define ADXL345_HIGHPASSFILTER_DISABLE ((uint8_t)0x00)

#define ADXL345_HIGHPASSFILTER_ENABLE ((uint8_t)0x10)

#define ADXL345_INT1INTERRUPT_DISABLE ((uint8_t)0x00)

#define ADXL345_INT1INTERRUPT_ENABLE ((uint8_t)0x80)

#define ADXL345_INT2INTERRUPT_DISABLE ((uint8_t)0x00)

#define ADXL345_INT2INTERRUPT_ENABLE ((uint8_t)0x08)

#define ADXL345_INT1INTERRUPT_LOW_EDGE ((uint8_t)0x20)

#define ADXL345_INT1INTERRUPT_HIGH_EDGE ((uint8_t)0x00)

#define ADXL345_BOOT_NORMALMODE ((uint8_t)0x00)

#define ADXL345_BOOT_REBOOTMEMORY ((uint8_t)0x80)

#define ADXL345_HPM_NORMAL_MODE_RES ((uint8_t)0x00)

#define ADXL345_HPM_REF_SIGNAL ((uint8_t)0x10)

#define ADXL345_HPM_NORMAL_MODE ((uint8_t)0x20)

#define ADXL345_HPM_AUTORESET_INT ((uint8_t)0x30)

#define ADXL345_HPFCF_0 0x00

#define ADXL345_HPFCF_1 0x01

#define ADXL345_HPFCF_2 0x02

#define ADXL345_HPFCF_3 0x03

#define ADXL345_HPFCF_4 0x04

#define ADXL345_HPFCF_5 0x05

#define ADXL345_HPFCF_6 0x06

#define ADXL345_HPFCF_7 0x07

#define ADXL345_HPFCF_8 0x08

#define ADXL345_HPFCF_9 0x09

#define ADXL345_CS_LOW() GPIO_ResetBits(ADXL345_SPI_CS_GPIO_PORT, ADXL345_SPI_CS_PIN)

#define ADXL345_CS_HIGH() GPIO_SetBits(ADXL345_SPI_CS_GPIO_PORT, ADXL345_SPI_CS_PIN)

void ADXL345_Init(ADXL345_InitTypeDef *ADXL345_InitStruct);

void ADXL345_RebootCmd(void);

void ADXL345_INT1InterruptCmd(uint8_t InterruptState);

void ADXL345_INT2InterruptCmd(uint8_t InterruptState);

void ADXL345_INT1InterruptConfig(ADXL345_InterruptConfigTypeDef *ADXL345_IntConfigStruct);

uint8_t ADXL345_GetDataStatus(void);

void ADXL345_FilterConfig(ADXL345_FilterConfigTypeDef *ADXL345_FilterStruct);

void ADXL345_FilterCmd(uint8_t HighPassFilterState);

void ADXL345_Write(uint8_t* pBuffer, uint8_t WriteAddr, uint16_t NumByteToWrite);

void ADXL345_Read(uint8_t* pBuffer, uint8_t ReadAddr, uint16_t NumByteToRead);

2.ADXL345的SPI配置函数

void SPI_init(void)

{

GPIO_InitTypeDef GPIO_InitStructure;

SPI_InitTypeDef SPI_InitStructure;

RCC_APB2PeriphClockCmd(RCC_APB2Periph_AFIO | RCC_APB2Periph_GPIOA |

RCC_APB2Periph_GPIOB, ENABLE);

RCC_APB2PeriphClockCmd(ADXL345_SPI_CLK ,ENABLE);

GPIO_StructInit(&GPIO_InitStructure);

GPIO_InitStructure.GPIO_Pin =ADXL345_SPI_CS_PIN ;

GPIO_InitStructure.GPIO_Mode=GPIO_Mode_Out_PP;

GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;

GPIO_Init(ADXL345_SPI_CS_GPIO_PORT, &GPIO_InitStructure);

GPIO_SetBits(ADXL345_SPI_CS_GPIO_PORT,ADXL345_SPI_CS_PIN);

GPIO_StructInit(&GPIO_InitStructure);

GPIO_InitStructure.GPIO_Pin =ADXL345_SPI_SCK_PIN|ADXL345_SPI_MISO_PIN|ADXL345_SPI_MOSI_PIN;

GPIO_InitStructure.GPIO_Mode=GPIO_Mode_AF_PP;

GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;

GPIO_Init(ADXL345_SPI_MOSI_GPIO_PORT, &GPIO_InitStructure);

SPI_InitStructure.SPI_Direction=SPI_Direction_2Lines_FullDuplex;

SPI_InitStructure.SPI_Mode=SPI_Mode_Master;

SPI_InitStructure.SPI_DataSize = SPI_DataSize_16b;

SPI_InitStructure.SPI_CPOL=SPI_CPOL_High;

SPI_InitStructure.SPI_CPHA=SPI_CPHA_2Edge;

SPI_InitStructure.SPI_NSS=SPI_NSS_Soft;

SPI_InitStructure.SPI_BaudRatePrescaler=SPI_BaudRatePrescaler_256;

SPI_InitStructure.SPI_FirstBit=SPI_FirstBit_MSB;

SPI_InitStructure.SPI_CRCPolynomial=7;

SPI_Init(ADXL345_SPI, &SPI_InitStructure);

SPI_Cmd(ADXL345_SPI,ENABLE);

}

3.ADXL345初始化配置函数

void ADXL345_init(void)

{

SPI_init(); //ADXL345¶Ë¿Ú³õʼ»¯ÅäÖÃSPIͨÐÅ

ADXL345_write_byte(0x1E,0x00); //X Æ«ÒÆÁ¿ ¸ù¾Ý²âÊÔ´«¸ÐÆ÷µÄ״̬дÈëpdf29Ò³ 0X00 (15.6mg/LSB)

ADXL345_write_byte(0x1F,0x00); //Y Æ«ÒÆÁ¿ ¸ù¾Ý²âÊÔ´«¸ÐÆ÷µÄ״̬дÈëpdf29Ò³ 0X00 (15.6mg/LSB)

ADXL345_write_byte(0x20,0x00); //Z Æ«ÒÆÁ¿ ¸ù¾Ý²âÊÔ´«¸ÐÆ÷µÄ״̬дÈëpdf29Ò³ 0X00 (15.6mg/LSB)

ADXL345_write_byte(0x21,0x00); //Çû÷ÑÓʱ0:½ûÓÃ; (1.25ms/LSB)

ADXL345_write_byte(0x22,0x00); //¼ì²âµÚÒ»´ÎÇû÷ºóµÄÑÓʱ0:½ûÓÃ; (1.25ms/LSB)

ADXL345_write_byte(0x23,0x00); //Çû÷´°¿Ú0:½ûÓÃ; (1.25ms/LSB)

ADXL345_write_byte(0x24,0x01); //±£´æ¼ì²â»î¶¯·§Öµ; (62.5mg/LSB)

ADXL345_write_byte(0x25,0x01); //±£´æ¼ì²â¾²Ö¹·§Öµ; (62.5mg/LSB)

ADXL345_write_byte(0x26,0x2B); //¼ì²â»î¶¯Ê±¼ä·§Öµ; (1s/LSB)

ADXL345_write_byte(0x27,0x00); //

ADXL345_write_byte(0x28,0x09); //×ÔÓÉÂäÌå¼ì²âÍƼö·§Öµ; (62.5mg/LSB)

ADXL345_write_byte(0x29,0xFF); //×ÔÓÉÂäÌå¼ì²âʱ¼ä·§Öµ,ÉèÖÃΪ×î´óʱ¼ä; (5ms/LSB)

ADXL345_write_byte(0x2A,0x80); //

//ADXL345_read_byte(0x2B); //Ö»¶Á¼Ä´æÆ÷,״̬¶ÁÈ¡

ADXL345_write_byte(0x2C,0x0F); //ËÙÂÊÉ趨Ϊ3200HZ²Î¿¼pdf13Ò³ 0X0A 1OO,0X0E 1600HZ

ADXL345_write_byte(0x2D,0x08); //Ñ¡ÔñµçԴģʽ¹Ø±Õ×Ô¶¯ÐÝÃß,ÐÝÃß,»½Ðѹ¦Äܲο¼pdf24Ò³

ADXL345_write_byte(0x2E,0x80); //ʹÄÜ DATA_READY ÖжÏ

ADXL345_write_byte(0x2F,0x00);

//ADXL345_read_byte(0x30); //Ö»¶Á¼Ä´æÆ÷,״̬¶ÁÈ¡

ADXL345_write_byte(0x31,0X0B); //Êý¾ÝͨПñʽ;ÉèÖÃΪ×Լ칦ÄܽûÓÃ,4ÏßÖÆSPI½Ó¿Ú,µÍµçƽÖжÏÊä³ö,13λȫ·Ö±æÂÊ,Êä³öÊý¾ÝÓÒ¶ÔÆë,16gÁ¿³Ì

ADXL345_write_byte(0x38,0x00); //FIFOģʽÉ趨,Streamģʽ£¬´¥·¢Á¬½ÓINT1,31¼¶Ñù±¾»º³å

//ADXL345_read_byte(0x39); //Ö»¶Á¼Ä´æÆ÷,״̬¶ÁÈ¡

}

4.ADXL345的读写函数

u8 ADXL345_read_byte(u8 add)

{

GPIO_ResetBits(ADXL345_SPI_CS_GPIO_PORT ,ADXL345_SPI_CS_PIN);

SPI_I2S_SendData(ADXL345_SPI,(add|0x80)<<8|0x00);

while(SPI_I2S_GetFlagStatus(ADXL345_SPI,SPI_I2S_FLAG_TXE)==RESET);

while(SPI_I2S_GetFlagStatus(ADXL345_SPI, SPI_I2S_FLAG_RXNE)==RESET);

GPIO_SetBits(ADXL345_SPI_CS_GPIO_PORT ,ADXL345_SPI_CS_PIN);

return SPI_I2S_ReceiveData(ADXL345_SPI)&0xff;

}

void ADXL345_write_byte(u8 add,u8 val)

{

GPIO_ResetBits(ADXL345_SPI_CS_GPIO_PORT ,ADXL345_SPI_CS_PIN);

SPI_I2S_SendData(ADXL345_SPI,add<<8|val);

while(SPI_I2S_GetFlagStatus(ADXL345_SPI,SPI_I2S_FLAG_TXE)==RESET);

while(SPI_I2S_GetFlagStatus(ADXL345_SPI, SPI_I2S_FLAG_RXNE)==RESET);

GPIO_SetBits(ADXL345_SPI_CS_GPIO_PORT ,ADXL345_SPI_CS_PIN);

SPI_I2S_ReceiveData(ADXL345_SPI)&0xff;

}

void ADXL345_ReadXYZ(float *g)

{

uint8_t BUF[6]; // ´æ·ÅX,Y,ZÖáµÄÊý¾Ý

int16_t temp;

BUF[0] = ADXL345_read_byte(0x32);

BUF[1] = ADXL345_read_byte(0x33);

delay_ms(1);

BUF[2] = ADXL345_read_byte(0x34);

BUF[3] = ADXL345_read_byte(0x35);

delay_ms(1);

BUF[4] = ADXL345_read_byte(0x36);

BUF[5] = ADXL345_read_byte(0x37);

delay_ms(1);

temp = (BUF[1] << 8) + BUF[0];

if(temp < 0)

temp = -temp;

g[0] = (float)(temp * 3.9); //¼ÆËãÊý¾ÝºÍÏÔʾ,²é¿¼ADXL345¿ìËÙÈëÃŵÚ4Ò³

temp = (BUF[3] << 8) + BUF[2];

if(temp < 0)

temp = -temp;

g[1] = (float)(temp * 3.9); //¼ÆËãÊý¾ÝºÍÏÔʾ,²é¿¼ADXL345¿ìËÙÈëÃŵÚ4Ò³

temp = (BUF[5] << 8) + BUF[4];

if(temp < 0)

temp = -temp;

g[2] = (float)(temp * 3.9); //¼ÆËãÊý¾ÝºÍÏÔʾ,²é¿¼ADXL345¿ìËÙÈëÃŵÚ4Ò³

}