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| ? | [[文件:02s03702.jpg|400px|縮略圖|右]]
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| ? | ==產(chǎn)品概述==
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| ? | ADXL345 數(shù)字三軸加速度計(jì)是一款小而薄的超低功耗3軸加速度計(jì)，分辨率高達(dá)(13位)，測(cè)量范圍達(dá)± 16g。數(shù)字輸出數(shù)據(jù)為16位二進(jìn)制補(bǔ)碼格式，可通過(guò)SPI(3線或4線)或I2C數(shù)字接口訪問(wèn)。ADXL345非常適合移動(dòng)設(shè)備應(yīng)用。它可以在傾斜檢測(cè)應(yīng)用中測(cè)量靜態(tài)重力加速度，還可以測(cè)量運(yùn)動(dòng)或沖擊導(dǎo)致的動(dòng)態(tài)加速度。其高分辨率(3.9mg/LSB)，能夠測(cè)量不到1.0°的傾斜角度變化。該器件提供多種特殊檢測(cè)功能?；顒?dòng)和非活動(dòng)檢測(cè)功能通過(guò)比較任意軸上的加速度與用戶設(shè)置的閾值來(lái)檢測(cè)有無(wú)運(yùn)動(dòng)發(fā)生。敲擊檢測(cè)功能可以檢測(cè)任意方向的單振和雙振動(dòng)作。自由落體檢測(cè)功能可以檢測(cè)器件是否正在掉落。這些功能可以獨(dú)立映射到兩個(gè)中斷輸出引腳中的一個(gè)。正在申請(qǐng)專利的集成式存儲(chǔ)器管理系統(tǒng)采用一個(gè)32級(jí)先進(jìn)先出(FIFO)緩沖器，可用于存儲(chǔ)數(shù)據(jù)，從而將主機(jī)處理器負(fù)荷降至最低，并降低整體系統(tǒng)功耗。低功耗模式支持基于運(yùn)動(dòng)的智能電源管理，從而以極低的功耗進(jìn)行閾值感測(cè)和運(yùn)動(dòng)加速度測(cè)量。
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| ? | ==規(guī)格參數(shù)==
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| ? | # 工作電壓：3.3-5v
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| ? | # 超低功耗：測(cè)量模式下40uA電流損耗，待機(jī)模式下0.1uA@2.5v
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| ? | # 通訊接口：I2C、SPI(3線or4線)
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| ? | # 接口類型：0.1"插針孔
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| ? | ==接口定義==
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| ? | * VCC：電源引腳
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| ? | * GND：該引腳必須接地
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| ? | * CS：片選端，低電平有效
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| ? | * INT1：中斷1輸出
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| ? | * INT2：中斷2輸出
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| ? | * SDO：備用I2C地址選擇
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| ? | * SDA：I2C接口數(shù)據(jù)端
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| ? | * SCL：I2C接口時(shí)鐘端
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| ? | ==使用方法==
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| ? | ===接線方法===
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| ? | [[文件:b1.png|423px|縮略圖|居中]]
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| ? | 接線圖：
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| ? | [[文件:Adxl345jiexian.jpg|700px|縮略圖|居中]]
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| ? | ===例子程序===
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| ? | [http://pan.baidu.com/s/1o6CI1ZG wire庫(kù)文件下載]
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| ? | <pre style='color:blue'>#include <Wire.h>
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| ? | #define DEVICE (0x53) //ADXL345 device address
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| ? | #define TO_READ (6) //num of bytes we are going to read each time (two bytes for each axis)
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| ? | byte buff[TO_READ] ; //6 bytes buffer for saving data read from the device
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| ? | char str[512]; //string buffer to transform data before sending it to the serial port
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| ? | int regAddress = 0x32; //first axis-acceleration-data register on the ADXL345
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| ? | int x, y, z; //three axis acceleration data
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| ? | double roll = 0.00, pitch = 0.00; //Roll & Pitch are the angles which rotate by the axis X and y
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| ? | //in the sequence of R(x-y-z),more info visit
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| ? | void setup() {
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| ? | Wire.begin(); // join i2c bus (address optional for master)
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| ? | Serial.begin(9600); // start serial for output
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| ? | //Turning on the ADXL345
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| ? | writeTo(DEVICE, 0x2D, 0);
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| ? | writeTo(DEVICE, 0x2D, 16);
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| ? | writeTo(DEVICE, 0x2D, 8);
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| ? | }
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| ? | void loop() {
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| ? | readFrom(DEVICE, regAddress, TO_READ, buff); //read the acceleration data from the ADXL345
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| ? | //each axis reading comes in 10 bit resolution, ie 2 bytes. Least Significat Byte first!!
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| ? | //thus we are converting both bytes in to one int
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| ? | x = (((int)buff[1]) << 8) | buff[0];
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| ? | y = (((int)buff[3])<< 8) | buff[2];
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| ? | z = (((int)buff[5]) << 8) | buff[4];
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| ? | //we send the x y z values as a string to the serial port
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| ? | Serial.print("The acceleration info of x, y, z are:");
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| ? | sprintf(str, "%d %d %d", x, y, z);
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| ? | Serial.print(str);
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| ? | Serial.write(10);
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| ? | //Roll & Pitch calculate
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| ? | RP_calculate();
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| ? | Serial.print("Roll:"); Serial.println( roll );
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| ? | Serial.print("Pitch:"); Serial.println( pitch );
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| ? | Serial.println("");
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| ? | //It appears that delay is needed in order not to clog the port
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| ? | delay(50);
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| ? | }
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| ? | //---------------- Functions
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| ? | //Writes val to address register on device
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| ? | void writeTo(int device, byte address, byte val) {
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| ? | Wire.beginTransmission(device); //start transmission to device
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| ? | Wire.write(address); // send register address
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| ? | Wire.write(val); // send value to write
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| ? | Wire.endTransmission(); //end transmission
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| ? | }
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| ? | //reads num bytes starting from address register on device in to buff array
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| ? | void readFrom(int device, byte address, int num, byte buff[]) {
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| ? | Wire.beginTransmission(device); //start transmission to device
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| ? | Wire.write(address); //sends address to read from
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| ? | Wire.endTransmission(); //end transmission
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| ? | Wire.beginTransmission(device); //start transmission to device
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| ? | Wire.requestFrom(device, num); // request 6 bytes from device
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| ? | int i = 0;
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| ? | while(Wire.available()) //device may send less than requested (abnormal)
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| ? | {
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| ? | buff[i] = Wire.read(); // receive a byte
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| ? | i++;
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| ? | }
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| ? | Wire.endTransmission(); //end transmission
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| ? | }
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| ? | //calculate the Roll&Pitch
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| ? | void RP_calculate(){
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| ? | double x_Buff = float(x);
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| ? | double y_Buff = float(y);
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| ? | double z_Buff = float(z);
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| ? | roll = atan2(y_Buff , z_Buff) * 57.3;
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| ? | pitch = atan2((- x_Buff) , sqrt(y_Buff * y_Buff + z_Buff * z_Buff)) * 57.3;
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| ? | }</pre>
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| ? | ===程序效果===
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| ? | 打開(kāi)串口監(jiān)視窗口，可以看到類似下圖的數(shù)據(jù)，分別為：三軸加速度的數(shù)據(jù)，按照R-xyz旋轉(zhuǎn)順序時(shí)的姿態(tài)角。按各軸旋轉(zhuǎn)可以觀測(cè)到相應(yīng)的數(shù)據(jù)變化。
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