NodeMCU_ESP8266_MMC5883MA-B.ino

/*
* The sample code requires the ESP8266 v.2.0.0 library for proper operation. 
* (https://github.com/ubidots/ubidots-esp8266/releases/tag/2.0.0) 
* However, is strongly recommended to migrate the code to the latest library version.
* (https://github.com/ubidots/ubidots-esp8266)
*/

#include <Wire.h>
#include "UbidotsMicroESP8266.h"

#define TOKEN  "Your_token_here"  // Put here your Ubidots TOKEN
#define WIFISSID "Your_WiFi_SSID" // Put here your Wi-Fi SSID
#define PASSWORD "Your_WiFi_Password" // Put here your Wi-Fi password

Ubidots client(TOKEN);

//*****************************************************
// MMC5883MA Register map
//*****************************************************
#define XOUT_LSB    0x00
#define XOUT_MSB    0x01
#define YOUT_LSB    0x02
#define YOUT_MSB    0x03
#define ZOUT_LSB    0x04
#define ZOUT_MSB    0x05
#define TEMPERATURE 0x06
#define STATUS      0x07
#define INT_CTRL0   0x08
#define INT_CTRL1   0x09
#define INT_CTRL2   0x0A
#define X_THRESHOLD 0x0B
#define Y_THRESHOLD 0x0C
#define Z_THRESHOLD 0x0D
#define PROD_ID1    0x2F

#define MMC5883MA   0x30                          // Sensor I2C address

#define MMC5883MA_DYNAMIC_RANGE 16
#define MMC5883MA_RESOLUTION    65536

//*****************************************************
// Functions declaration
//*****************************************************
char read_register(byte REG_ADDR);
void write_register(byte REG_ADDR, byte VALUE);
void wait_meas(void);
void reset_sensor(void);
float parser(char axis_msb, char axis_lsb);

//*****************************************************
// Setup
//*****************************************************
void setup() 
{
  Wire.begin();                                   // Join I2C bus (address optional for master)
  Serial.begin(9600);                             // Start USB serial port
  client.wifiConnection(WIFISSID, PASSWORD);
  write_register(INT_CTRL0, 0x04);                // SET instruction
}

//*****************************************************
// Main
//*****************************************************
void loop()
{
  Serial.println("---------");
  
  // Variables initialization
  char x_lsb, x_msb, y_lsb, y_msb, z_lsb, z_msb;
  float x_val, y_val, z_val;
  uint8_t status_reg = 0;
  uint8_t id = 0;
  uint8_t payload[6] = {};
  
  reset_sensor();
  
  write_register(INT_CTRL2, 0x40);                // Enables measurement interrupt
  write_register(STATUS, 0x01);                   // Clean measurement interrupt

  // Check status register before start magnetic field measurement
  status_reg = read_register(STATUS);
  //Serial.print("Status register before: ");
  //Serial.println(status_reg, BIN);
  
  //Serial.println("Starting measurement");
  write_register(INT_CTRL0, 0X01);                // Start magnetic field measurement

  wait_meas();
  
  // Check status register after complete magnetif field measurement
  status_reg = read_register(STATUS);
  //Serial.print("Status register after: ");
  //Serial.println(status_reg, BIN);
  
  x_lsb = read_register(XOUT_LSB);                // Read magnetic field - x lsb
  x_msb = read_register(XOUT_MSB);                // Read magnetic field - x msb
  y_lsb = read_register(YOUT_LSB);                // Read magnetic field - y lsb
  y_msb = read_register(YOUT_MSB);                // Read magnetic field - y msb
  z_lsb = read_register(ZOUT_LSB);                // Read magnetic field - z lsb
  z_msb = read_register(ZOUT_MSB);                // Read magnetic field - z msb

  x_val = parser(x_msb, x_lsb);
  y_val = parser(y_msb, y_lsb);
  z_val = parser(z_msb, z_lsb);

  Serial.print("Xout: ");
  Serial.println(x_val, 7);
  Serial.print("Yout: ");
  Serial.println(y_val, 7);
  Serial.print("Zout: ");
  Serial.println(z_val, 7);

//-------------------------------------------------
  // Ubidots payload
  client.setDataSourceName("nodemcu_mmc5883ma");
  client.setDataSourceLabel("nodemcu_mmc5883ma");
  client.add("x", x_val);
  client.add("y", y_val);
  client.add("z", z_val);
  client.sendAll(true);
//-------------------------------------------------
  
  delay(1000);
}

//*****************************************************
// Functions definition
//*****************************************************
char read_register(byte REG_ADDR)
{ 
  char reg_value = 0;

  Wire.beginTransmission(byte(MMC5883MA));        // Adress of I2C device
  Wire.write(byte(REG_ADDR));                     // Register address
  Wire.endTransmission();
  
  Wire.requestFrom(byte(MMC5883MA), 1);           // Request 1 byte from I2C slave device
  if (Wire.available() == 1)
  {
    reg_value = Wire.read();                      // Receive a byte as character
  } 
  Wire.endTransmission();
  return reg_value;
}
//-------------------------------------------------
void write_register(byte REG_ADDR, byte VALUE)
{
  Wire.beginTransmission(byte(MMC5883MA));        // Adress of I2C device
  Wire.write(byte(REG_ADDR));                     // Register address
  Wire.write(byte(VALUE));                        // Value to be written
  Wire.endTransmission();
}
//-------------------------------------------------
void reset_sensor()
{
  write_register(INT_CTRL1, 0x80);
  //Serial.println("Sensor reseted");
}
//-------------------------------------------------
void wait_meas()
{
  //Serial.println("Waiting for measurement");
  uint8_t status_reg = 0;
  uint8_t meas_finish = 0;
  byte mask = 1;

  while(meas_finish == 0)
  {
    status_reg = read_register(STATUS);
    meas_finish = status_reg & mask;
  }
  //Serial.println("Measurement finished");
}
//-------------------------------------------------
float parser(char MSB, char LSB)
{
  float ans = (float)(MSB << 8 | LSB) * MMC5883MA_DYNAMIC_RANGE / MMC5883MA_RESOLUTION - (float)MMC5883MA_DYNAMIC_RANGE / 2;
  return ans;
}