ciao
vi scrivo per sapere se c'è qualcuno che ha avuto modo di cimentarsi con l'uso del sensore ADXL345, ci lavoro da qualche giorno, con questo sketch
/*
I2C comunication
read acceleration value
CS pin 3v3
SDA pin SDA +10k to 3v3
SDO pin GND
SCL pin SCL +10k to 3v3
3v3 VCC
GND GND
*/
#include <Wire.h>
#define DEVICE (0x53) //ADXL345 device address
#define TO_READ (2) //num of bytes we are going to read each time (two bytes for each axis)
byte buff[TO_READ] ; //6 bytes buffer for saving data read from the device
char str[512]; //string buffer to transform data before sending it to the serial port
int regAddress;
int x, y, z;
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);
regAddress = 0x32; //first axis-acceleration-data register on the ADXL345
}
void loop()
{
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[1]) << 8) | buff[0];
y = (((int)buff[3])<< 8) | buff[2];
z = (((int)buff[5]) << 8) | buff[4];
/* //we send the x y z values as a string to the serial port
sprintf(str, "%d %d %d", x, y, z);
Serial.print(str);
Serial.write(10);
delay(15);//It appears that delay is needed in order not to clog the port
*/
//Print the results to the terminal.
Serial.println("buff[1] << 8, BIN");
Serial.println(buff[1] << 8, BIN);
Serial.println("buff[0], BIN");
Serial.println(buff[0], BIN);
Serial.println("buff[1] << 8 | buff[0], BIN");
Serial.println(buff[1] << 8 | buff[0], BIN);
Serial.println("x, BIN");
Serial.println(x, BIN);
Serial.println("x, DEC");
Serial.println(x, DEC);
/* Serial.print('\t');
Serial.print(y * 0.00390625, DEC);
Serial.print('\t');
Serial.print(z * 0.00390625, DEC);
Serial.print('\t');
Serial.println("m/sec2"); */
delay(20);//It appears that delay is needed in order not to clog the port
}
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
}
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 (initiate again)
Wire.requestFrom(device, num); // request 6 bytes from device
int i = 0;
while(Wire.available()) //device may send less than requested (abnormal)
{
buff[i] = Wire.read(); // receive a byte
// Serial.print(i);
// Serial.print('\t');
// Serial.println(buff[i], BIN);
i++;
}
Wire.endTransmission(); //end transmission
}
non ho avuto grossi problemi, mettendo dei serial qua e la ho avuto modo capire qualcosa, quello che non capisco è l'utilizzo di << e |, dal reference ho capito come funzionano, ma se provo ad applicare allo sketch non capisco perchè ottengo altri risultati, sicuramente sbaglio io, avete qualche indicazione.
Grazie
Stefano