HMC5883L and @file libcompass3d.c

oakguy

Hi
I tried running this sketch and the program seems to freeze at the second i2C instance. Can I ask why two instances are created?

int x, y, z; // Declare x, y, & z axis variables
pause(1000);
print("c32\n");
i2c *bus = i2c_newbus(3, 2, 0); // New I2C bus SCL=P3, SDA=P2
compass_init(bus); // Initialize compass on bus.


print("c54\n");
i2c *bus2 = i2c_newbus(5, 4, 0); // New I2C bus SCL=P3, SDA=P2
compass_init(bus2); // Initialize compass on bus.

My C sketch always freezes at the second instance. Any help is appreciated!

Oakguy

jazzed

Hi.

Do you mean that c54 is output and nothing else happens?
It's hard to tell, but it looks like your program ends after compass_init(bus2).

Is your code pasted into main() ?
If you copy/paste the whole file here, it would be clearer.

oakguy

Ok, here is the file from the learn folder bundled with the Activity Bot. You can see in Andy's file that there are two instances where he constructs the bus and the sketch seems to hang on that.

Thanks!

/*
* @file libcompass3d.c
*
* @author Andy Lindsay
*
* @copyright
* Copyright (C) Parallax, Inc. 2013. All Rights MIT Licensed.
*
* @brief Temporary project and test harness for the name library.
*
* SCL connected to P3 and SDA connected to P2. Display measurement results in
* SimpleIDE Terminal
*/


#include "simpletools.h" // Include simpletools header
#include "compass3d.h" // Include compass3d header
#include "simplei2c.h"


int main() // Main function
{




int x, y, z; // Declare x, y, & z axis variables
pause(1000);
print("c32\n");
i2c *bus = i2c_newbus(3, 2, 0); // New I2C bus SCL=P3, SDA=P2
compass_init(bus); // Initialize compass on bus.


print("c54\n");
i2c *bus2 = i2c_newbus(5, 4, 0); // New I2C bus SCL=P3, SDA=P2
compass_init(bus2); // Initialize compass on bus.


print("%c", HOME);


while(1) // Repeat indefinitely
{
print("%c", HOME);
print("c32\n");
compass_read(bus, &x, &y, &z); // Compass vals -> variables


int *px, *py, *pz;


px = &x;
py = &y;
pz = &z;

*px = x;
*py = y;
*pz = z;


float heading = atan2(x, y);
if(heading < 0)
{
heading += 2.0 * 3.14;
}

float headingDegrees = heading * 180/3.14;


print("\nx=%d, y=%d, z=%d%c\n", // Display raw compass values
x, y, z, CLREOL);
print("heading = %f, \n", // Display raw compass values
headingDegrees);
waitcnt(CLKFREQ/2+CNT);


print("c54\n");
compass_read(bus2, &x, &y, &z); // Compass vals -> variables


px = &x;
py = &y;
pz = &z;

*px = x;
*py = y;
*pz = z;


heading = atan2(x, y);
if(heading < 0)
{
heading += 2.0 * 3.14;
}

headingDegrees = heading * 180/3.14;


print("\nx=%d, y=%d, z=%d%c\n", // Display raw compass values
x, y, z, CLREOL);
print("heading = %f, \n", // Display raw compass values
headingDegrees);
pause(500); // Wait 1/2 second
}




}

jazzed

I see.

So, you have added a second compass?

I have an appointment this afternoon ... maybe Andy will see this.

Andy Lindsay (Parallax)

I would not recommend using the test harness code from the library folder. Instead, open Test Compass HMC5883L.side from this folder and run it:

...\Documents\SimpleIDE\Learn\Examples\Devices\Sensor\Compass 3-Axis HMC5883L

Andy

oakguy

Andy
Your right, that sketch does run without error, however, it does not return a 0 - 360 heading value. Just so I'm running the right one:
Test Compass HMC5883L.c


Version 0.94 for use with SimpleIDE 9.40 and its Simple Libraries

Test compass with SCL connected to P3 and SDA connected to P2. Display
measurement results in SimpleIDE Terminal.

learn.parallax.com/propeller-c-tutorials

I only get a -70 to a -80 for a heading.

Thanks
Guy

oakguy

Andy
I checked the math and the formulas are correct. Perhaps its my chip that is defective. I entered the y and x in Excel and ended up with the same value your sketch computed! My bad!



206
-1583
-82.6275
-76.3475



Thanks
Guy

Andy Lindsay (Parallax)

Thanks for the update. I just tested it with a compass and board I've got on-hand, and it correctly reported the entire 360-degree range of headings.

Let's check and make sure our circuits match:

Compass GND -> Activity Board GND
Compass VIN -> Activity Board 3.3 V
Compass SCL -> 100 ohm resistor (brown-black-brown) -> Activity Board P3
Compass SDA -> 100 ohm resistor (brown-black-brown) -> Activity Board P2

NOTE: 220 ohm resistors (red-red-brown) are okay too.

Another item to check is possible interference from strong sources of magnetic fields. Sometimes a metal brace under the table can be magnetized and affects the measurements. Nearby components and wires can also affect the measurements, but not to the point where they appear to be stuck in one position. I usually hold my board well above the table when I test.

Last item, make sure you've got the latest Learn folder and SimpleIDE:

SimpleIDE v0.9.43
http://learn.parallax.com/propeller-c-set-simpleide

Learn folder 2013.11.01
http://learn.parallax.com/propeller-c-set-simpleide/update-your-learn-folder

Example Code from ....Documents\SimpleIDE\Learn\Examples\Devices\Sensor\Compass 3-Axis HMC5883L\

/*
  Test Compass HMC5883L.c

  Version 0.94 for use with SimpleIDE 9.40 and its Simple Libraries
  
  Test compass with SCL connected to P3 and SDA connected to P2. Display
  measurement results in SimpleIDE Terminal.
  
 learn.parallax.com/propeller-c-tutorials
*/

#include "simpletools.h"                      // Include simpletools header
#include "compass3d.h"                        // Include compass3d header

int main()                                    // main function
{
  int x, y, z;                                // Declare x, y, & z axis variables
  
  i2c *bus = i2c_newbus(3, 2, 0);             // New I2C bus SCL=P3, SDA=P2
  compass_init(bus);                          // Initialize compass on bus.

  while(1)                                    // Repeat indefinitely
  {
    compass_read(bus, &x, &y, &z);            // Compass vals -> variables
    print("%cx=%d, y=%d, z=%d%c\n",           // Display compass variables
           HOME, x, y, z, CLREOL);

    float fy = (float) y;                     // Ints to floats
    float fx = (float) x;
    float heading = atan2(fy, fx) * 180.0/PI; // Calculate heading with floats
    if(heading < 0.0)                         // Convert -180...+180 to 0...360
      heading = (360.0 + heading);
    print("heading = %.2f%c\n",               // Display heading
                        heading, CLREOL);       

    pause(500);                               // Wait 1/2 second
  }
}