multiple_MAG3110_Logger.ino

#include <pca9547.h>
#include <BME280_MOD-1022.h>
#include <Wire.h>

/// constants
const uint8_t NUM_DEVICES = 4;
const int NUM_AVG = 5000;
const int WX_AVG = 5;
#define MAG_ADDR  0x0E //7-bit address for the MAG3110, doesn't change
/// initialize a PCA9547 instance on the default address.
PCA9547 i2c_bus_splitter;

void setup()
{

  Serial.begin(9600); 
  Wire.begin();
  
  // Setup each magnetometer
  for (uint8_t i=0; i<NUM_DEVICES; i++)
  {
    i2c_bus_splitter.setBusChannel(i);
    delay(1);
    config();

  }
  
  i2c_bus_splitter.setBusChannel(NUM_DEVICES);
  delay(1);
  // Setup BME280
  BME280.writeStandbyTime(tsb_0p5ms);        // tsb = 0.5ms
  BME280.writeFilterCoefficient(fc_16);      // IIR Filter coefficient 16
  BME280.writeOversamplingPressure(os16x);    // pressure x16
  BME280.writeOversamplingTemperature(os2x);  // temperature x2
  BME280.writeOversamplingHumidity(os1x);     // humidity x1
  BME280.writeMode(smNormal);
  
}


void loop()
{
  // Read each magnetometer
  for (uint8_t i=0; i<NUM_DEVICES; i++)
  {
    i2c_bus_splitter.setBusChannel(i);
    delay(1);
    log_mag(i);

  }
  
  // Read the weather parameters
  i2c_bus_splitter.setBusChannel(NUM_DEVICES);
  delay(1);
  log_wx(NUM_DEVICES);
}

void log_wx(int bus_num)
{
    float temperature = 0;
    float humidity = 0;
    float pressure = 0;
    
    for(int i = 0; i<WX_AVG; i++){
        BME280.readCompensationParams();  
        while (BME280.isMeasuring()) {}
        BME280.readMeasurements();
        temperature += BME280.getTemperatureMostAccurate();
        humidity += BME280.getHumidityMostAccurate();
        pressure += BME280.getPressureMostAccurate();
    }
    
  temperature = temperature/WX_AVG;
  humidity = humidity/WX_AVG;
  pressure = pressure/WX_AVG;
  
  Serial.print(bus_num+1);
  Serial.print(",");
  Serial.print(millis());
  Serial.print(",");
  Serial.print(temperature);
  Serial.print(",");
  Serial.print(humidity);
  Serial.print(",");
  Serial.println(pressure);
    
}

void log_mag(int bus_num)
{
  float mag_x = 0;
  float mag_y = 0;
  float mag_z = 0;  
  
  for (int i=0; i<NUM_AVG; i++)
  {
    mag_x += read_x();
    mag_y += read_y();
    mag_z += read_z();
  }
  
  mag_x /= NUM_AVG;
  mag_y /= NUM_AVG;
  mag_z /= NUM_AVG;

  Serial.print(bus_num+1);
  Serial.print(",");
  Serial.print(millis());
  Serial.print(",");
  Serial.print(mag_x);
  Serial.print(",");
  Serial.print(mag_y);
  Serial.print(",");
  Serial.println(mag_z);
}

int read_x(void)
{
  int xl, xh;  //define the MSB and LSB
  
  Wire.beginTransmission(MAG_ADDR); // transmit to device 0x0E
  Wire.write(0x01);              // x MSB reg
  Wire.endTransmission();       // stop transmitting
 
  delayMicroseconds(2); //needs at least 1.3us free time between start and stop
  
  Wire.requestFrom(MAG_ADDR, 1); // request 1 byte
  while(Wire.available())    // slave may send less than requested
  { 
    xh = Wire.read(); // receive the byte
  }
  
  delayMicroseconds(2); //needs at least 1.3us free time between start and stop
  
  Wire.beginTransmission(MAG_ADDR); // transmit to device 0x0E
  Wire.write(0x02);              // x LSB reg
  Wire.endTransmission();       // stop transmitting
 
  delayMicroseconds(2); //needs at least 1.3us free time between start and stop
  
  Wire.requestFrom(MAG_ADDR, 1); // request 1 byte
  while(Wire.available())    // slave may send less than requested
  { 
    xl = Wire.read(); // receive the byte
  }
  
  int xout = (xl|(xh << 8)); //concatenate the MSB and LSB
  return xout;
}

int read_y(void)
{
  int yl, yh;  //define the MSB and LSB
  
  Wire.beginTransmission(MAG_ADDR); // transmit to device 0x0E
  Wire.write(0x03);              // y MSB reg
  Wire.endTransmission();       // stop transmitting
 
  delayMicroseconds(2); //needs at least 1.3us free time between start and stop
  
  Wire.requestFrom(MAG_ADDR, 1); // request 1 byte
  while(Wire.available())    // slave may send less than requested
  { 
    yh = Wire.read(); // receive the byte
  }
  
  delayMicroseconds(2); //needs at least 1.3us free time between start and stop
  
  Wire.beginTransmission(MAG_ADDR); // transmit to device 0x0E
  Wire.write(0x04);              // y LSB reg
  Wire.endTransmission();       // stop transmitting
 
  delayMicroseconds(2); //needs at least 1.3us free time between start and stop
  
  Wire.requestFrom(MAG_ADDR, 1); // request 1 byte
  while(Wire.available())    // slave may send less than requested
  { 
    yl = Wire.read(); // receive the byte
  }
  
  int yout = (yl|(yh << 8)); //concatenate the MSB and LSB
  return yout;
}

int read_z(void)
{
  int zl, zh;  //define the MSB and LSB
  
  Wire.beginTransmission(MAG_ADDR); // transmit to device 0x0E
  Wire.write(0x05);              // z MSB reg
  Wire.endTransmission();       // stop transmitting
 
  delayMicroseconds(2); //needs at least 1.3us free time between start and stop
  
  Wire.requestFrom(MAG_ADDR, 1); // request 1 byte
  while(Wire.available())    // slave may send less than requested
  { 
    zh = Wire.read(); // receive the byte
  }
  
  delayMicroseconds(2); //needs at least 1.3us free time between start and stop
  
  Wire.beginTransmission(MAG_ADDR); // transmit to device 0x0E
  Wire.write(0x06);              // z LSB reg
  Wire.endTransmission();       // stop transmitting
 
  delayMicroseconds(2); //needs at least 1.3us free time between start and stop
  
  Wire.requestFrom(MAG_ADDR, 1); // request 1 byte
  while(Wire.available())    // slave may send less than requested
  { 
    zl = Wire.read(); // receive the byte
  }
  
  int zout = (zl|(zh << 8)); //concatenate the MSB and LSB
  return zout;
}

void config(void)
{
  Wire.beginTransmission(MAG_ADDR); // transmit to device 0x0E
  Wire.write(0x11);              // cntrl register2
  Wire.write(0x80);              // send 0x80, enable auto resets
  Wire.endTransmission();       // stop transmitting
  
  delay(15);
  
  Wire.beginTransmission(MAG_ADDR); // transmit to device 0x0E
  Wire.write(0x10);              // cntrl register1
  Wire.write(1);                 // send 0x01, active mode
  Wire.endTransmission();       // stop transmitting
}

PCA9547.pdf