Hello guys,
i am using a digilent 3axis digital compass to measure the magnetic field on a current wire to detect the state of a device. The signal turned out to be like wavy, so that i cant get thresholds easily (look at photo). In the beginning it can be seen that the device is off, and then it is turned on and then it is used(between 8000-10000). But how can i make a threshold analysis? like if the magnetic field is above 0 it is on and if its above 100 it is used otherwise its off. With this signal its difficult to be done because its compared to a sine wave.....
please help here is code and photo
#define DECLINATION 2.39 // declination (in degrees).
/************************************************************************/
#include <Wire.h> //including library for I2C communication
unsigned char CMPS2_address = 0x30; //I2C address of the device
int taster=7;
int tasterstatus=0;
void setup() {
Serial.begin(9600); //serial initialization
delay(10);
CMPS2_init(); //initialize the compass
pinMode(taster, INPUT);
}
float data[3];
unsigned int raw[3];
float offset[3];
float current[3];
float field[3];
float rms;
int Cycles = 0;
void loop()
{
tasterstatus=digitalRead(taster);
if (tasterstatus == LOW)
{
Serial.println("Feldunterdrückung");
for (int i=0;i<3;i++)
{
field[i] = data[i];
}
}
for (int i=0;i<3;i++)
{
current[i] = data[i]-field[i];
}
rms = sqrt(sq(current[0])+sq(current[1])+sq(current[2]));
}
//delay(250);
//retrieving and displaying the heading of the compass
float angle = CMPS2_getHeading();
Serial.println(rms);
//CMPS2_decodeHeading(angle); //get direction
}
void CMPS2_decodeHeading(float angle) {
//decoding heading angle according to datasheet
if (angle > 337.25 | angle < 22.5) {
Serial.println("North");
}
else if (angle > 292.5) {
Serial.println("North-West");
}
else if (angle > 247.5) {
Serial.println("West");
}
else if (angle > 202.5) {
Serial.println("South-West");
}
else if (angle > 157.5) {
Serial.println("South");
}
else if (angle > 112.5) {
Serial.println("South-East");
}
else if (angle > 67.5) {
Serial.println("East");
}
else {
Serial.println("North-East");
}
}
float CMPS2_getHeading(void) {
CMPS2_read_XYZ(); //read X, Y, Z data of the magnetic field
//eliminate offset before continuing
for (int i=0;i<3;i++)
{
data[i] = data[i]-offset[i];
}
//variables for storing partial results
float temp0 = 0;
float temp1 = 0;
//and for storing the final result
float deg = 0;
//calculate heading from data of the magnetic field
//the formula is different in each quadrant
if (data[0] < 0)
{
if (data[1] > 0)
{
//Quadrant 1
temp0 = data[1];
temp1 = -data[0];
deg = 90 - atan(temp0 / temp1) * (180 / 3.14159);
}
else
{
//Quadrant 2
temp0 = -data[1];
temp1 = -data[0];
deg = 90 + atan(temp0 / temp1) * (180 / 3.14159);
}
}
else {
if (data[1] < 0)
{
//Quadrant 3
temp0 = -data[1];
temp1 = data[0];
deg = 270 - atan(temp0 / temp1) * (180 / 3.14159);
}
else
{
//Quadrant 4
temp0 = data[1];
temp1 = data[0];
deg = 270 + atan(temp0 / temp1) * (180 / 3.14159);
}
}
//correct heading
deg += DECLINATION;
if (DECLINATION > 0)
{
if (deg > 360) {
deg -= 360;
}
}
else
{
if (deg < 0) {
deg += 360;
}
}
return deg;
}
//reads measurements in mG
void CMPS2_read_XYZ(void) {
//initialize array for data
//command internal control register 0 bit 0 (measure)
Wire.beginTransmission(CMPS2_address);
Wire.write(0x07);
Wire.write(0x01);
Wire.endTransmission();
delay(8);
//wait for measurement to be completed
bool flag = false;
while (!flag) {
//jump to status register
Wire.beginTransmission(CMPS2_address);
Wire.write(0x06);
Wire.endTransmission();
//read its value
Wire.requestFrom(CMPS2_address, (uint8_t)1);
int temporal = 0;
if (Wire.available()) {
temporal = Wire.read();
}
//if the last bit is 1, data is ready
temporal &= 1;
if (temporal != 0) {
flag = true;
}
}
//move address pointer to first address
Wire.beginTransmission(CMPS2_address);
Wire.write(0x00);
Wire.endTransmission();
//save data
Wire.requestFrom(CMPS2_address, (uint8_t)6);
byte tmp[6] = {0, 0, 0, 0, 0, 0}; //array for raw data
if (Wire.available()) {
for (int i = 0; i < 6; i++) {
tmp[i] = Wire.read(); //save it
}
}
//reconstruct raw data
raw[0] = tmp[1] << 8 | tmp[0]; //x
raw[1] = tmp[3] << 8 | tmp[2]; //y
raw[2] = tmp[5] << 8 | tmp[4]; //z
//convert raw data to 1mG
for (int i = 0; i < 3; i++) {
data[i] = 0.48828125 * (float)raw[i];
}
}
//initialize the compass
//Update: this should follow Calibration steps
void CMPS2_init(void) {
float out1[3];
float out2[3];
int i;
Wire.begin(); // initialization of I2C bus
//calibration: SET
Wire.beginTransmission(CMPS2_address);
Wire.write(0x07);
delay(10);
Wire.write(0x80);
Wire.endTransmission();
delay(80);
Wire.beginTransmission(CMPS2_address);
Wire.write(0x07);
delay(10);
Wire.write(0x20);
Wire.endTransmission();
delay(10);
CMPS2_read_XYZ();
for (i=0;i<3;i++)
{
out1[i] = data[i];
}
Serial.print("Raw SET = ");
Serial.print(raw[0]);
Serial.print("\t");
Serial.print(raw[1]);
Serial.print("\t");
Serial.println(raw[2]);
//calibration: RESET
Wire.beginTransmission(CMPS2_address);
Wire.write(0x07);
delay(10);
Wire.write(0x80);
Wire.endTransmission();
delay(60);
Wire.beginTransmission(CMPS2_address);
Wire.write(0x07);
delay(10);
Wire.write(0x40);
Wire.endTransmission();
delay(10);
CMPS2_read_XYZ();
for (i=0;i<3;i++)
{
out2[i] = data[i];
}
Serial.print("Raw RESET = ");
Serial.print(raw[0]);
Serial.print("\t");
Serial.print(raw[1]);
Serial.print("\t");
Serial.println(raw[2]);
//offset calculation
for (i=0;i<3;i++)
{
offset[i] = (out1[i]+out2[i])*0.5;
}
//command internal control register 0 for set operation
Wire.beginTransmission(CMPS2_address);
Wire.write(0x07);
delay(10);
Wire.write(0x40); //SET
Wire.endTransmission();
delay(10);
//command internal control register 1 to 16 bit resolution, 8ms measurement time
Wire.beginTransmission(CMPS2_address);
Wire.write(0x08);
delay(10);
Wire.write(0x00);
Wire.endTransmission();
delay(10);
}
