Arduino Digital Compass With Tilt Compensation and Compass Graphic on SSD1306 OLED

In this video lesson we develop a graphical compass dial on a SSD1306 OLED for our digital compass. For this project, we are using the following schematic:

OLED IMU — This schematic shows how to connect the SSD1306 OLED to our IMU Project.

Below for your convenience we include the code developed in this lesson. Remember you must use your own calibration numbers in the code below. I show you how to calibrate your own GY-87 in THIS LESSON.

#include <Adafruit_MPU6050.h>
#include <Adafruit_Sensor.h>
#include <Wire.h>
#include <QMC5883LCompass.h>

#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>
#include <math.h>

int screenWidth=128;
int screenHeight=64;
int rst = -1;
Adafruit_SSD1306 dsp(screenWidth, screenHeight, &Wire, rst);

float AxRaw,AyRaw,AzRaw,GxRaw,GyRaw,GzRaw,MxRaw,MyRaw,MzRaw;
float AxCal,AyCal,AzCal,GxCal,GyCal,GzCal,MxCal,MyCal,MzCal;
float rollA,pitchA,yawM,rollC,pitchC,yawC;
float rollG = 0;
float pitchG =0 ;
float yawG = 0;
float deltaRoll = 0;
float deltaPitch = 0;
float deltaYaw = 0;
float alpha = .1;

float rollCrad;
float pitchCrad;
float MxCalH;
float MyCalH;

int tStart =millis();
Adafruit_MPU6050 mpu;
QMC5883LCompass compass;

void setup() {
  // put your setup code here, to run once:
Serial.begin(115200);

dsp.begin(SSD1306_SWITCHCAPVCC,0x3C);
dsp.clearDisplay();
dsp.display();

mpu.begin();
mpu.setI2CBypass(true);
compass.init();
mpu.setGyroRange(MPU6050_RANGE_1000_DEG);
delay(100);
}

void calibrateSensors() {
    const float axOffset = 0.45407887789180545;
    const float ayOffset = 0.09432915233553185;
    const float azOffset = -0.4614157209191969;
    const float axScale = 0.10141341897341144;
    const float ayScale = 0.10141341897341144;
    const float azScale = 0.10141341897341144;
    const float gxOffset = -2.277507235645022;
    const float gyOffset = 0.8794902155258137;
    const float gzOffset = -0.5729577951308232;
    const float mxOffset = -103.48885017294003;
    const float myOffset = -96.80085481152321;
    const float mzOffset = 923.8042898128733;
    const float mxScale = 0.001156333898601669;
    const float myScale = 0.001012882116988885;
    const float mzScale = 0.0009400860982065997;


    AxCal = (AxRaw - axOffset) * axScale;
    AyCal = (AyRaw - ayOffset) * ayScale;
    AzCal = (AzRaw - azOffset) * azScale;
    GxCal = GxRaw*180/PI - gxOffset;
    GyCal = GyRaw*180/PI - gyOffset;
    GzCal = GzRaw*180/PI - gzOffset;
    MxCal = (MxRaw - mxOffset) * mxScale;
    MyCal = (MyRaw - myOffset) * myScale;
    MzCal = (MzRaw - mzOffset) * mzScale;
}
void updateDial(){
int radius=20;
int offset=3;
int x1Center = radius;
int y1Center = 63 - radius;

int x1;
int y1;
int x2;
int y2;
float angleRad;
float tickScale;
dsp.drawCircle(x1Center,y1Center,radius, WHITE);
for (int i=0; i<=360; i=i+30){
  angleRad = i*PI/180;
  tickScale=.9;
  if (i%90==0){
    tickScale=.7;
  }
  x1 =x1Center + int(tickScale*radius*cos(angleRad));
  y1 =y1Center + int(tickScale*radius*sin(angleRad));
  x2 = x1Center + int(radius*cos(angleRad));
  y2 = y1Center + int(radius*sin(angleRad));
  dsp.drawLine(x1,y1,x2,y2,WHITE);
}
x1=x1Center;
y1=y1Center;
x2= x1Center + radius*cos(-(yawC+90)*PI/180);
y2= y1Center + radius*sin(-(yawC+90)*PI/180);
dsp.drawLine(x1,y1,x2,y2,WHITE);
}

void loop() {
  // put your main code here, to run repeatedly:
compass.read();
sensors_event_t a, g, temp;
mpu.getEvent(&a, &g, &temp);

AxRaw = a.acceleration.x;
AyRaw = a.acceleration.y;
AzRaw = a.acceleration.z;

GxRaw = g.gyro.x;
GyRaw = g.gyro.y;
GzRaw = g.gyro.z;

MxRaw= compass.getX();
MyRaw= compass.getY();
MzRaw= compass.getZ();

calibrateSensors();

rollA = atan2(AyCal,sqrt(AzCal*AzCal + AxCal*AxCal))*180/PI;
pitchA = atan2(AxCal,sqrt(AzCal*AzCal + AyCal*AyCal))*180/PI;

deltaRoll = GxCal*(millis()-tStart)/1000.;
deltaPitch = -GyCal*(millis()-tStart)/1000.;
deltaYaw = -GzCal*(millis()-tStart)/1000.;
tStart = millis();

rollG = rollG + deltaRoll;
pitchG = pitchG + deltaPitch;
yawG = yawG + deltaYaw;

rollC = alpha*(rollA) + (1-alpha)*(rollC+deltaRoll);
pitchC = alpha*(pitchA) + (1-alpha)*(pitchC+deltaPitch);

rollCrad=rollC*PI/180;
pitchCrad=pitchC*PI/180;

MxCalH=MxCal*cos(pitchCrad)-MyCal*sin(rollCrad)*sin(pitchCrad)-MzCal*cos(rollCrad)*sin(pitchCrad);
MyCalH=MyCal*cos(rollCrad) - MzCal*sin(rollCrad);

yawM = atan2(MyCalH,MxCalH)*180./PI;
yawM=int(yawM+360)%360;
if (abs(yawM-yawC)>=180){
  yawC=yawM;
}
if (abs(yawM-yawC)<180){
yawC = alpha*(yawM) + (1-alpha)*(yawC + deltaYaw);
}

// Serial.print("yawC:");Serial.print(yawC);Serial.print(',');
// Serial.print("yawM:");Serial.print(yawM);Serial.print(',');
// Serial.print("yawG:");Serial.print(yawG);Serial.print(',');
// Serial.print("LL:");Serial.print(-90);Serial.print(',');
// Serial.print("UL:");Serial.println(90);

Serial.print("rollC:");Serial.print(rollC);Serial.print(',');
Serial.print("pitchC:");Serial.print(pitchC);Serial.print(',');
Serial.print("yawC:");Serial.print(yawC);Serial.print(',');
Serial.print("LL:");Serial.print(-90);Serial.print(',');
Serial.print("UL:");Serial.println(90);

dsp.clearDisplay();
dsp.setTextColor(WHITE);
dsp.setCursor(0,0);
dsp.print("Ultimate Avionics");
dsp.setCursor(0,9);
dsp.print("R: "); dsp.print(int(rollC));
dsp.setCursor(40,9);
dsp.print("P: ");dsp.print(int(pitchC));
dsp.setCursor(80,9);
dsp.print("Y: ");dsp.print(int(yawC));

updateDial();

dsp.display();
delay(100);
}

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#include <Adafruit_MPU6050.h>

#include <Adafruit_Sensor.h>

#include <Wire.h>

#include <QMC5883LCompass.h>

#include <Adafruit_GFX.h>

#include <Adafruit_SSD1306.h>

#include <math.h>

int screenWidth=128;

int screenHeight=64;

int rst = -1;

Adafruit_SSD1306 dsp(screenWidth, screenHeight, &Wire, rst);

float AxRaw,AyRaw,AzRaw,GxRaw,GyRaw,GzRaw,MxRaw,MyRaw,MzRaw;

float AxCal,AyCal,AzCal,GxCal,GyCal,GzCal,MxCal,MyCal,MzCal;

float rollA,pitchA,yawM,rollC,pitchC,yawC;

float rollG = 0;

float pitchG =0 ;

float yawG = 0;

float deltaRoll = 0;

float deltaPitch = 0;

float deltaYaw = 0;

float alpha = .1;

float rollCrad;

float pitchCrad;

float MxCalH;

float MyCalH;

int tStart =millis();

Adafruit_MPU6050 mpu;

QMC5883LCompass compass;

void setup() {

// put your setup code here, to run once:

Serial.begin(115200);

dsp.begin(SSD1306_SWITCHCAPVCC,0x3C);

dsp.clearDisplay();

dsp.display();

mpu.begin();

mpu.setI2CBypass(true);

compass.init();

mpu.setGyroRange(MPU6050_RANGE_1000_DEG);

delay(100);

}

void calibrateSensors() {

const float axOffset = 0.45407887789180545;

const float ayOffset = 0.09432915233553185;

const float azOffset = -0.4614157209191969;

const float axScale = 0.10141341897341144;

const float ayScale = 0.10141341897341144;

const float azScale = 0.10141341897341144;

const float gxOffset = -2.277507235645022;

const float gyOffset = 0.8794902155258137;

const float gzOffset = -0.5729577951308232;

const float mxOffset = -103.48885017294003;

const float myOffset = -96.80085481152321;

const float mzOffset = 923.8042898128733;

const float mxScale = 0.001156333898601669;

const float myScale = 0.001012882116988885;

const float mzScale = 0.0009400860982065997;

AxCal = (AxRaw - axOffset) * axScale;

AyCal = (AyRaw - ayOffset) * ayScale;

AzCal = (AzRaw - azOffset) * azScale;

GxCal = GxRaw*180/PI - gxOffset;

GyCal = GyRaw*180/PI - gyOffset;

GzCal = GzRaw*180/PI - gzOffset;

MxCal = (MxRaw - mxOffset) * mxScale;

MyCal = (MyRaw - myOffset) * myScale;

MzCal = (MzRaw - mzOffset) * mzScale;

}

void updateDial(){

int radius=20;

int offset=3;

int x1Center = radius;

int y1Center = 63 - radius;

int x1;

int y1;

int x2;

int y2;

float angleRad;

float tickScale;

dsp.drawCircle(x1Center,y1Center,radius, WHITE);

for (int i=0; i<=360; i=i+30){

angleRad = i*PI/180;

tickScale=.9;

if (i%90==0){

tickScale=.7;

}

x1 =x1Center + int(tickScale*radius*cos(angleRad));

y1 =y1Center + int(tickScale*radius*sin(angleRad));

x2 = x1Center + int(radius*cos(angleRad));

y2 = y1Center + int(radius*sin(angleRad));

dsp.drawLine(x1,y1,x2,y2,WHITE);

}

x1=x1Center;

y1=y1Center;

x2= x1Center + radius*cos(-(yawC+90)*PI/180);

y2= y1Center + radius*sin(-(yawC+90)*PI/180);

dsp.drawLine(x1,y1,x2,y2,WHITE);

}

void loop() {

// put your main code here, to run repeatedly:

compass.read();

sensors_event_t a, g, temp;

mpu.getEvent(&a, &g, &temp);

AxRaw = a.acceleration.x;

AyRaw = a.acceleration.y;

AzRaw = a.acceleration.z;

GxRaw = g.gyro.x;

GyRaw = g.gyro.y;

GzRaw = g.gyro.z;

MxRaw= compass.getX();

MyRaw= compass.getY();

MzRaw= compass.getZ();

calibrateSensors();

rollA = atan2(AyCal,sqrt(AzCal*AzCal + AxCal*AxCal))*180/PI;

pitchA = atan2(AxCal,sqrt(AzCal*AzCal + AyCal*AyCal))*180/PI;

deltaRoll = GxCal*(millis()-tStart)/1000.;

deltaPitch = -GyCal*(millis()-tStart)/1000.;

deltaYaw = -GzCal*(millis()-tStart)/1000.;

tStart = millis();

rollG = rollG + deltaRoll;

pitchG = pitchG + deltaPitch;

yawG = yawG + deltaYaw;

rollC = alpha*(rollA) + (1-alpha)*(rollC+deltaRoll);

pitchC = alpha*(pitchA) + (1-alpha)*(pitchC+deltaPitch);

rollCrad=rollC*PI/180;

pitchCrad=pitchC*PI/180;

MxCalH=MxCal*cos(pitchCrad)-MyCal*sin(rollCrad)*sin(pitchCrad)-MzCal*cos(rollCrad)*sin(pitchCrad);

Technology Tutorials

Arduino Digital Compass With Tilt Compensation and Compass Graphic on SSD1306 OLED

Making The World a Better Place One High Tech Project at a Time. Enjoy!