提高三軸 ADXL345 速率
我想要讓輸出資料達到每秒2000筆的資料可是就算使用3200hz 的速率 每秒就只能輸出55筆資料
請問我要如何提高採集速率或是輸出速率 謝謝
#include <Wire.h>
#define DEVICE (0x53) //ADXL345 device address
#define TO_READ (6) //num of bytes we are going to read each time (two bytes for each axis)
byte buff ; //6 bytes buffer for saving data read from the device
char str; //string buffer to transform data before sending it to the serial port
int a=0;
void setup()
{
Wire.begin(); // join i2c bus (address optional for master)
Serial.begin(9600);// start serial for output
//Turning on the ADXL345
writeTo(DEVICE, 0x2D, 0);
writeTo(DEVICE, 0x2D, 16);
writeTo(DEVICE, 0x2D, 8);
writeTo(DEVICE, 0x2C, 15);
}
void loop()
{
int regAddress = 0x32; //first axis-acceleration-data register on the ADXL345
int x, y, z;
readFrom(DEVICE, regAddress, TO_READ, buff); //read the acceleration data from the ADXL345
//each axis reading comes in 10 bit resolution, ie 2 bytes.Least Significat Byte first!!
//thus we are converting both bytes in to one int
x = (((int)buff) << 8) | buff;
y = (((int)buff)<< 8) | buff;
z = (((int)buff) << 8) | buff;
//we send the x y z values as a string to the serial port
sprintf(str, "%d %d %d", x, y, z);
a=a+1;
Serial.println(a);
Serial.println(millis());
//Serial.println(str);
// Serial.write(10);
//It appears that delay is needed in order not to clog the port
delay(15);
}
//---------------- Functions
//Writes val to address register on device
void writeTo(int device, byte address, byte val) {
Wire.beginTransmission(device); //start transmission to device
Wire.write(address); // send register address
Wire.write(val); // send value to write
Wire.endTransmission(); //end transmission
}
//reads num bytes starting from address register on device in to buff array
void readFrom(int device, byte address, int num, byte buff[]) {
Wire.beginTransmission(device); //start transmission to device
Wire.write(address); //sends address to read from
Wire.endTransmission(); //end transmission
Wire.beginTransmission(device); //start transmission to device
Wire.requestFrom(device, num); // request 6 bytes from device
int i = 0;
while(Wire.available()) //device may send less than requested (abnormal)
{
buff = Wire.read(); // receive a byte
i++;
}
Wire.endTransmission(); //end transmission
}
LZ你有点搞晕了！
把345设置的输出率很高3.2k，它有能力输出，但你的程序现在没有这么快的速度去读的：先不说读345寄存器要不要消耗时间，就光一个delay(15);，每次延时15ms，这个语句就控制你程序1秒钟只能读66.6666……次的，肯定不会有你想要的结果
还有，你设置波特率是9600，也就是1s传输1200byte，再按照你的程序设计，3轴数据每次6个字节，还有变量a，millis(),这样加起来每次要传10多个的字节，算下来1s也就能传输100次左右数据的
I-robofan 发表于 2014-4-27 11:57 static/image/common/back.gif
LZ你有点搞晕了！
把345设置的输出率很高3.2k，它有能力输出，但你的程序现在没有这么快的速度去读的：先不 ...
感謝解答 原來如此~~ 那我提高了最高波特率115200 雖然數據有明顯提升到500筆 但是與預想還有差距
會不會跟COM本身限制有關 還是有什麼方法能夠在提高呢
謝謝 andysleep 发表于 2014-4-27 12:39 static/image/common/back.gif
感謝解答 原來如此~~ 那我提高了最高波特率115200 雖然數據有明顯提升到500筆 但是與預想還有差距
會不會 ...
首先你要明白你要1s读2000次的目的是什么？测试什么极限，还是真的有需求，否则完全没必要1s读2000次的！
还有IIC是也有速度限制(100kHz,400kHz,或者其他的），程序还要跑其他代码，这些都需要时间消耗的，
不要去纠结1s读2000次了，完全没多大意义的
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