ESP8266 Community Forum

Posted: **Sun Jul 17, 2022 3:12 am**

Hello,
Very new to coding of anysort other than some VBA.
I picked up an ESP8266 last week and some motors and sensors, im playing around trying to build a vehicle that can navigate a GPS route.

I so far have a driving robot that can avoid obstacles using ultrasonic sensor.
I have attached a compass and can get it to produce somewhat accurate readings but im aware that it needs to be calibrated.

I have been attempting to get this code to work with my gy273 compass (confirmed HMC5883L)
https://github.com/helscream/HMC5883L_H ... alibration

When i upload the test code i get an error and Exception

Exception 0 - illegal instruction....
Decoding stack results
0x40201087: setup() at ~\Arduino\Magmaster compasscalib\Arduino_Code\HMC5883L\HMC5883L_Example/HMC5883L_Example.ino line 47
0x402024a8: loop_wrapper() at ~\AppData\Local\Arduino15\packages\esp8266\hardware\esp8266\3.0.2\cores\esp8266\core_esp8266_main.cpp line 198

Code is here

Code: Select all

/*
HMC5883L_Example.pde - Example sketch for integration with an HMC5883L triple axis magnetomerwe.
Copyright (C) 2011 Love Electronics (loveelectronics.co.uk)

This program is free software: you can redistribute it and/or modify
it under the terms of the version 3 GNU General Public License as
published by the Free Software Foundation.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program.  If not, see <http://www.gnu.org/licenses/>.

*/

// Reference the I2C Library
#include <Wire.h>
// Reference the HMC5883L Compass Library
#include <HMC5883L.h>

// Store our compass as a variable.
HMC5883L compass;
// Record any errors that may occur in the compass.
int error = 0;

// Out setup routine, here we will configure the microcontroller and compass.
void setup()
{
  // Initialize the serial port.
  Serial.begin(9600);

  Serial.println("Starting the I2C interface.");
  Wire.begin(); // Start the I2C interface.

  Serial.println("Constructing new HMC5883L");
  compass = HMC5883L(); // Construct a new HMC5883 compass.
    
  Serial.println("Setting scale to +/- 1.3 Ga");
  error = compass.SetScale(1.3); // Set the scale of the compass.   ****LINE 47****
  if(error != 0) // If there is an error, print it out.
    Serial.println(compass.GetErrorText(error));
  
  Serial.println("Setting measurement mode to continous.");
  error = compass.SetMeasurementMode(Measurement_Continuous); // Set the measurement mode to Continuous
  if(error != 0) // If there is an error, print it out.
    Serial.println(compass.GetErrorText(error));
}

// Our main program loop.
void loop()
{
  // Retrive the raw values from the compass (not scaled).
  MagnetometerRaw raw = compass.ReadRawAxis();
  // Retrived the scaled values from the compass (scaled to the configured scale).
  MagnetometerScaled scaled = compass.ReadScaledAxis();
  
  // Values are accessed like so:
  int MilliGauss_OnThe_XAxis = scaled.XAxis;// (or YAxis, or ZAxis)

  // Calculate heading when the magnetometer is level, then correct for signs of axis.
  float heading = atan2(scaled.YAxis, scaled.XAxis);
  
  // Once you have your heading, you must then add your 'Declination Angle', which is the 'Error' of the magnetic field in your location.
  // Find yours here: http://www.magnetic-declination.com/
  // Mine is: 2� 37' W, which is 2.617 Degrees, or (which we need) 0.0456752665 radians, I will use 0.0457
  // If you cannot find your Declination, comment out these two lines, your compass will be slightly off.
  float declinationAngle = 0.0457;
  heading += declinationAngle;
  
  // Correct for when signs are reversed.
  if(heading < 0)
    heading += 2*PI;
    
  // Check for wrap due to addition of declination.
  if(heading > 2*PI)
    heading -= 2*PI;
   
  // Convert radians to degrees for readability.
  float headingDegrees = heading * 180/M_PI; 

  // Output the data via the serial port.
  Output(raw, scaled, heading, headingDegrees);

  // Normally we would delay the application by 66ms to allow the loop
  // to run at 15Hz (default bandwidth for the HMC5883L).
  // However since we have a long serial out (104ms at 9600) we will let
  // it run at its natural speed.
  // delay(66);
}

// Output the data down the serial port.
void Output(MagnetometerRaw raw, MagnetometerScaled scaled, float heading, float headingDegrees)
{
   Serial.print("Raw:\t");
   Serial.print(raw.XAxis);
   Serial.print("   ");   
   Serial.print(raw.YAxis);
   Serial.print("   ");   
   Serial.print(raw.ZAxis);
   Serial.print("   \tScaled:\t");
   
   Serial.print(scaled.XAxis);
   Serial.print("   ");   
   Serial.print(scaled.YAxis);
   Serial.print("   ");   
   Serial.print(scaled.ZAxis);

   Serial.print("   \tHeading:\t");
   Serial.print(heading);
   Serial.print(" Radians   \t");
   Serial.print(headingDegrees);
   Serial.println(" Degrees   \t");
}

Serial Print

⸮Starting the I2C interface.
Constructing new HMC5883L
Setting scale to +/- 1.3 Ga
Entered scale was not valid, valid gauss values are: 0.88, 1.3, 1.9, 2.5, 4.0, 4.7, 5.6, 8.1
Setting measurement mode to continous.

To me this means "error = compass.SetScale(1.3);" is causing the error? or is the library not compatible with the ESP8266?

Thanks for any guidance

Posted: **Tue Jul 19, 2022 10:52 pm**

Looks like The library link that you have posted and the code are not the same.

INterfacing the HMC and ESP8266 is straight forward and you should not face any problems.
Try with this library - https://github.com/adafruit/Adafruit_HMC5883_Unified

Posted: **Wed Jul 20, 2022 1:33 am**

Hi there,

Thankyou for your reply. i can get the compass to report values to the serial monitor using this bit of code i found and have added some extra stuff to get it to print to my phone via wifi so i can take it outdoors and see the compass heading.

Code: Select all

/*
  Rui Santos
  Complete project details at https://RandomNerdTutorials.com/esp8266-nodemcu-webserial-library/
  
  This sketch is based on the WebSerial library example: ESP8266_Demo
  https://github.com/ayushsharma82/WebSerial
*/

#include <Arduino.h>
#include <ESP8266WiFi.h>
#include <ESPAsyncTCP.h>
#include <ESPAsyncWebServer.h>
#include <WebSerial.h>

#define LED 2

#include <Wire.h>

/* Define declination of location from where measurement going to be done. 
e.g. here we have added declination from location Pune city, India. 
we can get it from http://www.magnetic-declination.com */
#define Declination       -0.0095
#define hmc5883l_address  0x1E

AsyncWebServer server(80);

 const char* ssid = "P30pro";
 const char* password = "password";
 
void recvMsg(uint8_t *data, size_t len){
  WebSerial.println("Received Data...");
  String d = "";
  for(int i=0; i < len; i++){
    d += char(data[i]);
  }
  WebSerial.println(d);
  if (d == "ON"){
    digitalWrite(LED, LOW);
  }
  if (d=="OFF"){
    digitalWrite(LED, HIGH);
  }
}

void setup() {

  Serial.begin(9600); /* begin serial for debug */
  Wire.begin(D6, D5); /* join i2c bus with SDA=D6 and SCL=D5 of NodeMCU */
  hmc5883l_init();
  
  Serial.begin(9600);
  pinMode(LED, OUTPUT);
  digitalWrite(LED, HIGH);
  WiFi.mode(WIFI_STA);
  WiFi.begin(ssid, password);
  if (WiFi.waitForConnectResult() != WL_CONNECTED) {
    Serial.printf("WiFi Failed!\n");
    return;
  }
    Serial.println();
  Serial.println();
  Serial.print("Connecting to ");
  Serial.println(ssid);
  Serial.println("IP Address: ");
  Serial.print("http://");    //URL IP to be typed in mobile/desktop browser
  Serial.print(WiFi.localIP());
  Serial.println("/webserial");
 
  WebSerial.begin(&server);
  WebSerial.msgCallback(recvMsg);
  server.begin();
}


void hmc5883l_init(){   /* Magneto initialize function */
  Wire.beginTransmission(hmc5883l_address);
  Wire.write(0x00);
  Wire.write(0x70); //8 samples per measurement, 15Hz data output rate, Normal measurement 
  Wire.write(0xA0); //
  Wire.write(0x00); //Continuous measurement mode
  Wire.endTransmission();
  delay(500);
}

int hmc5883l_GetHeading(){
  int16_t x, y, z;
  double Heading;
  Wire.beginTransmission(hmc5883l_address);
  Wire.write(0x03);
  Wire.endTransmission();
  /* Read 16 bit x,y,z value (2's complement form) */
  Wire.requestFrom(hmc5883l_address, 6);
  x = (((int16_t)Wire.read()<<8) | (int16_t)Wire.read());
  z = (((int16_t)Wire.read()<<8) | (int16_t)Wire.read());
  y = (((int16_t)Wire.read()<<8) | (int16_t)Wire.read());

  Heading = atan2((double)y, (double)x) + Declination;
  if (Heading>2*PI) /* Due to declination check for >360 degree */
   Heading = Heading - 2*PI;
  if (Heading<0)    /* Check for sign */
   Heading = Heading + 2*PI;
  return (Heading* 180 / PI);/* Convert into angle and return */
}

/* Uncomment below function for reading status register */
//uint8_t readStatus(){
//  Wire.beginTransmission(hmc5883l_address);
//  Wire.write(0x09);
//  Wire.endTransmission();
//  Wire.requestFrom(hmc5883l_address, 1);
//  return (uint8_t) Wire.read();
//}


void loop() {
  Serial.print("Heading Angle : ");
  Serial.println(hmc5883l_GetHeading());
  delay(2000);
  
  WebSerial.print("Heading Angle : ");
  WebSerial.println(hmc5883l_GetHeading());
  delay(2000);
}

But i think the compass needs calibration as its values are not what my handheld compass shows.
The Library above has a calibration function that i cant find in any others.

Is there another way to calibrate the HMC5883L magnetometer with ESP2866?

Thanks Neil

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