An Experimental IMU demo with some initial mag calibration code.

Dependencies:   LSM9DS1_Library_cal mbed

This IMU demo prints to the USB virtual com port. It includes initial calibration, and scales the IMU readings to meaningful values that are printed out.

Files at this revision

API Documentation at this revision

Comitter:
4180_1
Date:
Wed Feb 03 18:47:07 2016 +0000
Commit message:
ver 0.0

Changed in this revision

LSM9DS1_Library_cal.lib Show annotated file Show diff for this revision Revisions of this file
main.cpp Show annotated file Show diff for this revision Revisions of this file
mbed.bld Show annotated file Show diff for this revision Revisions of this file
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/LSM9DS1_Library_cal.lib	Wed Feb 03 18:47:07 2016 +0000
@@ -0,0 +1,1 @@
+https://developer.mbed.org/users/4180_1/code/LSM9DS1_Library_cal/#36abf8e18ade
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/main.cpp	Wed Feb 03 18:47:07 2016 +0000
@@ -0,0 +1,79 @@
+#include "mbed.h"
+#include "LSM9DS1.h"
+#define PI 3.14159
+// Earth's magnetic field varies by location. Add or subtract
+// a declination to get a more accurate heading. Calculate
+// your's here:
+// http://www.ngdc.noaa.gov/geomag-web/#declination
+#define DECLINATION -4.94 // Declination (degrees) in Atlanta,GA.
+
+DigitalOut myled(LED1);
+Serial pc(USBTX, USBRX);
+// Calculate pitch, roll, and heading.
+// Pitch/roll calculations taken from this app note:
+// http://cache.freescale.com/files/sensors/doc/app_note/AN3461.pdf?fpsp=1
+// Heading calculations taken from this app note:
+// http://www51.honeywell.com/aero/common/documents/myaerospacecatalog-documents/Defense_Brochures-documents/Magnetic__Literature_Application_notes-documents/AN203_Compass_Heading_Using_Magnetometers.pdf
+void printAttitude(float ax, float ay, float az, float mx, float my, float mz)
+{
+    float roll = atan2(ay, az);
+    float pitch = atan2(-ax, sqrt(ay * ay + az * az));
+// touchy trig stuff to use arctan to get compass heading (scale is 0..360)
+    mx = -mx;
+    float heading;
+    if (my == 0.0)
+        heading = (mx < 0.0) ? 180.0 : 0.0;
+    else
+        heading = atan2(mx, my)*360.0/(2.0*PI);
+    //pc.printf("heading atan=%f \n\r",heading);
+    heading -= DECLINATION; //correct for geo location
+    if(heading>180.0) heading = heading - 360.0;
+    else if(heading<-180.0) heading = 360.0 + heading;
+    else if(heading<0.0) heading = 360.0  + heading;
+
+
+    // Convert everything from radians to degrees:
+    //heading *= 180.0 / PI;
+    pitch *= 180.0 / PI;
+    roll  *= 180.0 / PI;
+
+    pc.printf("Pitch: %f,    Roll: %f degress\n\r",pitch,roll);
+    pc.printf("Magnetic Heading: %f degress\n\r",heading);
+}
+
+
+
+
+int main()
+{
+    //LSM9DS1 lol(p9, p10, 0x6B, 0x1E);
+    LSM9DS1 IMU(p28, p27, 0xD6, 0x3C);
+    IMU.begin();
+    if (!IMU.begin()) {
+        pc.printf("Failed to communicate with LSM9DS1.\n");
+    }
+    IMU.calibrate(1);
+    IMU.calibrateMag(0);
+    while(1) {
+        while(!IMU.tempAvailable());
+        IMU.readTemp();
+        while(!IMU.magAvailable(X_AXIS));
+        IMU.readMag();
+        while(!IMU.accelAvailable());
+        IMU.readAccel();
+        while(!IMU.gyroAvailable());
+        IMU.readGyro();
+        pc.printf("\nIMU Temperature = %f C\n\r",25.0 + IMU.temperature/16.0);
+        pc.printf("        X axis    Y axis    Z axis\n\r");
+        pc.printf("gyro:  %9f %9f %9f in deg/s\n\r", IMU.calcGyro(IMU.gx), IMU.calcGyro(IMU.gy), IMU.calcGyro(IMU.gz));
+        pc.printf("accel: %9f %9f %9f in Gs\n\r", IMU.calcAccel(IMU.ax), IMU.calcAccel(IMU.ay), IMU.calcAccel(IMU.az));
+        pc.printf("mag:   %9f %9f %9f in gauss\n\r", IMU.calcMag(IMU.mx), IMU.calcMag(IMU.my), IMU.calcMag(IMU.mz));
+        printAttitude(IMU.calcAccel(IMU.ax), IMU.calcAccel(IMU.ay), IMU.calcAccel(IMU.az), IMU.calcMag(IMU.mx),
+                      IMU.calcMag(IMU.my), IMU.calcMag(IMU.mz));
+        myled = 1;
+        wait(0.5);
+        myled = 0;
+        wait(0.5);
+    }
+}
+
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/mbed.bld	Wed Feb 03 18:47:07 2016 +0000
@@ -0,0 +1,1 @@
+http://mbed.org/users/mbed_official/code/mbed/builds/165afa46840b
\ No newline at end of file