Linkit One and MLX90393 magnetic field sensor example

The MLX90393 magnetic field sensor can be reprogrammed to different modes and with different settings at run-time. The sensor offers a 16-bit output proportional to the magnetic flux density sensed along the XYZ axes using the Melexis proprietary Triaxis® technology and also offers a temperature output signal. These digital values are available via I2C and SPI, where the MLX90393 is a slave on the bus.

By selecting which axes are to be measured, the raw data can be used as input for further post-processing, such as for joystick applications, rotary knobs, and more complex 3D position sensing applications. Unparallelled performance is achieved with this sensor, which is primarily targeting industrial and consumer applications.

Connection

Here is the connection, its an I2C device so its easy to connect to your Linkit one

Code

[codesyntax lang=”cpp”]

#include<Wire.h>

// MLX90393 I2C Address is 0x0C(12)
#define Addr 0x0C

void setup() 
{
  // Initialise I2C communication as MASTER 
  Wire.begin();
  // Initialise serial communication, set baud rate = 9600
  Serial.begin(9600);

  // Start I2C Transmission
  Wire.beginTransmission(Addr);
  // Select Write register command
  Wire.write(0x60);
  // Set AH = 0x00, BIST disabled
  Wire.write(0x00);
  // Set AL = 0x5C, Hall plate spinning rate = DEFAULT, GAIN_SEL = 5  
  Wire.write(0x5C);
  // Select address register, (0x00 << 2)
  Wire.write(0x00);
  // Stop I2C Transmission
  Wire.endTransmission();

  // Request 1 byte of data
  Wire.requestFrom(Addr, 1);

  // Read status byte
  if(Wire.available() == 1) 
  {
    unsigned int c = Wire.read();
  }

  // Start I2C Transmission
  Wire.beginTransmission(Addr);
  // Select Write register command
  Wire.write(0x60);
  // Set AH = 0x02
  Wire.write(0x02);
  // Set AL = 0xB4, RES for magnetic measurement = 0
  Wire.write(0xB4);
  // Select address register, (0x02 << 2)
  Wire.write(0x08);
  // Stop I2C Transmission
  Wire.endTransmission();
  
  // Request 1 byte of data
  Wire.requestFrom(Addr, 1);

  // Read status byte
  if(Wire.available() == 1) 
  {
   unsigned int c = Wire.read();
  }
  delay(300);
}

void loop() 
{
  unsigned int data[7];
  
  // Start I2C Transmission
  Wire.beginTransmission(Addr);
  // Start single meaurement mode,  ZYX enabled
  Wire.write(0x3E);
  // Stop I2C Transmission
  Wire.endTransmission();
  
  // Request 1 byte of data
  Wire.requestFrom(Addr, 1);
  
  // Read status byte
  if(Wire.available() == 1) 
  {
   unsigned int c = Wire.read();
  }
  delay(100);

  // Start I2C Transmission
  Wire.beginTransmission(Addr);
  // Send read measurement command, ZYX enabled
  Wire.write(0x4E);
  // Stop I2C Transmission
  Wire.endTransmission();
  
  // Request 7 bytes of data
  Wire.requestFrom(Addr, 7);

  // Read 7 bytes of data
  // status, xMag msb, xMag lsb, yMag msb, yMag lsb, zMag msb, zMag lsb
  if(Wire.available() == 7);
  {
    data[0] = Wire.read();
    data[1] = Wire.read();
    data[2] = Wire.read();
    data[3] = Wire.read();
    data[4] = Wire.read();
    data[5] = Wire.read();
    data[6] = Wire.read();
  }

  // Convert the data
  int xMag = data[1] * 256 + data[2];
  int yMag = data[3] * 256 + data[4];
  int zMag = data[5] * 256 + data[6];

  // Output data to serial monitor
  Serial.print("Magnetic Field in X-Axis : ");
  Serial.println(xMag);
  Serial.print("Magnetic Field in Y-Axis : ");
  Serial.println(yMag);
  Serial.print("Magnetic Field in Z-Axis : ");
  Serial.println(zMag);
  delay(500);
}

[/codesyntax]

Output

Open the serial monitor and you should see something like this

Magnetic Field in X-Axis : 2462
Magnetic Field in Y-Axis : 1838
Magnetic Field in Z-Axis : 64370
Magnetic Field in X-Axis : 2534
Magnetic Field in Y-Axis : 2001
Magnetic Field in Z-Axis : 64341
Magnetic Field in X-Axis : 2485
Magnetic Field in Y-Axis : 1762
Magnetic Field in Z-Axis : 64328
Magnetic Field in X-Axis : 2508
Magnetic Field in Y-Axis : 1824
Magnetic Field in Z-Axis : 64334

Links

https://www.melexis.com/-/media/files/documents/datasheets/mlx90393-datasheet-melexis.pdf

CJMCU-90393, MLX90393 digital 3D Holzer sensor, displacement, angle, rotation, 3D position