File content as of revision 3:ce743dbbd4a5:

#include "mbed.h"
#include "Motor.h"
#include "Servo.h"
#include "LSM9DS1.h"
#include <math.h>

#define PI 3.14159
#define DECLINATION -4.94
#define DIST_FACTOR 0.107475 //cm/tick Conversion between a tick from Hall effect sensor and linear distance.
                            //Approximately 190 ticks for a full wheel rotation.
                            //Approximately 6.5cm wheel diameter
                            //pi*diameter (cm) / 190(ticks)
volatile float heading;
void getHeading(float ax, float ay, float az, float mx, float my, float mz);
float PI_cont(float err);

//MOTOR PINS
Motor rwheel(p22, p18, p17); // pwmA, fwd / Ain2, rev / Ain1
Motor lwheel(p23, p15, p16); // pwmB, fwd / Bin2, rev / 
//BLUETOOTH PINS
Serial bt(p28,p27);
//LEFT SONAR
DigitalOut triggerL(p14);
DigitalIn echoL(p12);
//RIGHT SONAR
DigitalOut triggerR(p13);
DigitalIn echoR(p11);
int correction = 0; //Used to adjust software delay for sonar measurement
Timer sonar;

//SERVO PINS
Servo angle(p21);
//IMU PINS
LSM9DS1 imu(p9, p10, 0xD6, 0x3C);
Ticker nav;
float posX = 0;
float posY = 0;
int tickDistL = 0;
int tickDistR = 0;

Serial pc(USBTX, USBRX);
Timer timestamp;

// Set up Hall-effect control
InterruptIn EncR(p25);
InterruptIn EncL(p24);
int ticksR = 0; // Encoder wheel state change counts
int ticksL = 0;
float speedL = 0; //PWM speed setting for left wheel (scaled between 0 and 1)
float speedR = 0; //Same for right wheel
int dirL = 1; //1 for fwd, -1 for reverse
int dirR = 1; //1 for fwd, -1 for reverse
Ticker Sampler; //Interrupt Routine to sample encoder ticks.
int tracking = 0; //Flag used to indicate right wheel correction

//PI controller
//global variables
float kp=12.0f;
float ki=4.0f;
float kd=1.0f;
float P=0;
float I=0;
float D=0;
float dt=0.1f;
float out=0.0f;
float max=0.5f;
float min=-0.5f;
float prerr=0.0f;

//Sample encoders and find error on right wheel. Assume Left wheel is always correct speed.
void sampleEncoder()
{
    float E; // Error  between the 2 wheel speeds
    if(tracking) { //Right wheel "tracks" left wheel if enabled. 

        E = ticksL - ticksR; //Find error
        //E = (ticksL+1)/(ticksR+1);
        if (dirL == 1)
        {
            speedR = speedR + float(E) / 255.0f; //Assign a scaled increment to the right wheel based on error
            //speedR = E*speedR;
            if (speedR < 0) speedR = 0;
        }
        else if (dirL == -1)
        {
            speedR = speedR - float(E) / 255.0f; //Assign a scaled increment to the right wheel based on error
            //speedR = E*speedR;
            if (speedR > 0) speedR = 0;
        }
        rwheel.speed(speedR);
    }
    //pc.printf("tickL: %i   tickR: %i  Error: %i\n\r ",ticksL, ticksR, ticksL - ticksR);
    ticksR = 0; //Restart the counters
    ticksL = 0;
}

void getHeading(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;
    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;
}

float PI_cont(float err)
{    
     float Pout=kp*err;
     P=Pout;
     //pc.printf("P is: %f \n\r",P);
     
     float Iout=Iout+err*dt;
     I=ki*Iout;
     //pc.printf("I is: %f \n\r",I);
     
     float Dout = (err - prerr)/dt;
     D=kd*Dout;
     
     out=P+I+D;
     
     prerr=err;
     
     //pc.printf("out is: %f \n\r",out); // basically pwm out
     if (out>max)out=max;
     else if (out<min)out=min;        
     return out;
}

void turn(float angle)
{
        float s =0.05;//speed by which the robot should turn
        while(!imu.magAvailable(X_AXIS));
        imu.readMag();
        while(!imu.accelAvailable());
        imu.readAccel();
        while(!imu.gyroAvailable());
        imu.readGyro();
        getHeading(imu.calcAccel(imu.ax), imu.calcAccel(imu.ay), imu.calcAccel(imu.az), imu.calcMag(imu.mx),
                      imu.calcMag(imu.my), imu.calcMag(imu.mz));
        float PV = heading;//the original heading
        float SP = heading - angle;//the new required heading
        if(SP>=360){//reseting after 360 degrees to 0
            SP = SP-360;
            }
        pc.printf("PV: %f\n",PV);
        pc.printf("SV: %f\n",SP);
        wait(2);
        //pc.printf("required: %f\n",requiredHeading);
        float error = angle;
         pc.printf("error: %f\n",error);
         int reached = 0;
         while(reached ==0){
         
                while(!imu.magAvailable(ALL_AXIS));
                imu.readMag();
                getHeading(imu.calcAccel(imu.ax), imu.calcAccel(imu.ay), imu.calcAccel(imu.az), imu.calcMag(imu.mx),
                      imu.calcMag(imu.my), imu.calcMag(imu.mz));
                PV = heading;//calculate the current heading
                
                error=(PV-SP)/360;//find error between current heading and required heading
                float correction=PI_cont(error);//correction to motor speed
                     if (error> 1.5/360 || error<-1.5/360) { //an error limit of 1.5 degrees allowed.. checking if the robot needs to turn more
                            rwheel.speed((s+correction)/2);
                            lwheel.speed((s-correction)/2);
                            pc.printf("error in 1st if: %f\n\r",error);
                            pc.printf("error in 1st if: %f\n\r",error);
                            }
                    else if (error>=-1.5/360 && error<=1.5/360) { //within within satisfying angular range 
                             rwheel.speed(0);
                             lwheel.speed(0);//stop moving and exit the loop
                             pc.printf("error in 2nd if: %f\n\r",error);
                             break;
                              }       
                              wait(0.01);                  
                        }
   
    rwheel.speed(0);
    lwheel.speed(0);
}


void sendCmd(char cmd, float arg)
{
    unsigned char c[sizeof arg];
    memcpy(c, &arg, sizeof arg);
    bt.putc('!');
    bt.putc(cmd);
    bt.putc(c[0]);
    bt.putc(c[1]);
    bt.putc(c[2]);
    bt.putc(c[3]);

}

int ping(int i)
{
    float distance = 0;
    switch(i)
    {
        
        case(1): //Ping Left Sonar
        // trigger sonar to send a ping
        pc.printf("Pinging sonar 1...\n\r");
        triggerL = 1;
        sonar.reset();
        //wait_us(10.0);
        //wait for echo high
        while (echoL==0) {};
        //echo high, so start timer
        sonar.start();
        triggerL = 0;
        //wait for echo low
        while (echoL==1) {};
        //stop timer and read value
        sonar.stop();
        //subtract software overhead timer delay and scale to cm
        distance = (sonar.read_us()-correction)/58.0;
        pc.printf("Got distance %f cm back.\n\r", distance);
        //wait so that any echo(s) return before sending another ping
        wait(0.015);
        break;
        case(2): //Ping Right Sonar
        // trigger sonar to send a ping
        pc.printf("Pinging sonar 2...\n\r");
        triggerR = 1;
        sonar.reset();
        //wait_us(10.0);
        //wait for echo high
        while (echoR==0) {};
        //echo high, so start timer
        sonar.start();
        triggerR = 0;
        //wait for echo low
        while (echoR==1) {};
        //stop timer and read value
        sonar.stop();
        //subtract software overhead timer delay and scale to cm
        distance = (sonar.read_us()-correction)/58.0;
        pc.printf("Got distance %f cm back.\n\r", distance);
        //wait so that any echo(s) return before sending another ping
        wait(0.015);
        break;
        default:
        break;
    } 
    return distance;
}

void sweep()
{
    int dL = 0;
    int dR = 0;
    if (angle <=0.5) //Set to min angle and execute forward sweep.
    {
        angle = 0;
        wait(.5);
        while( angle >= 0 && angle < 1)
        {
            dL = ping(1);
            dR = ping(2);
            sendCmd('D',dL);
            sendCmd('D',dR);
            angle = angle + 0.05;
        }
        angle = 1;
    }
    else if (angle > 0.5) //Set to max angle and execute backward sweep.
    {
        angle = 1;
        wait(.5);
        while( angle > 0 && angle <= 1)
        {
            dL = ping(1);
            dR = ping(2);
            sendCmd('D',dL);
            sendCmd('D',dR);
            angle = angle - 0.05;
        }
        angle = 0;
    }
}

void updatePos()
{
    float deltaX;
    float deltaY;
    float dist;
    while(!imu.magAvailable(X_AXIS));
    imu.readMag();
    while(!imu.accelAvailable());
    imu.readAccel();
    while(!imu.gyroAvailable());
    imu.readGyro();
    getHeading(imu.calcAccel(imu.ax), imu.calcAccel(imu.ay), imu.calcAccel(imu.az), imu.calcMag(imu.mx),
                  imu.calcMag(imu.my), imu.calcMag(imu.mz));
    dist = (tickDistR + tickDistL)/2.0f*DIST_FACTOR; //Average the ticks and convert to linear distance.
    pc.printf("Magnetic Heading: %f degress    ",heading);
    pc.printf("L ticks: %d   R ticks: %d       ",tickDistL, tickDistR);
    tickDistR = 0;//Reset the ticks.
    tickDistL = 0;
    deltaX = dist*(float)sin((double)heading*PI/180.0f); //Do trig.
    deltaY = dist*(float)cos((double)heading*PI/180.0f);
    posX = posX + deltaX;
    posY = posY + deltaY;
    pc.printf("deltaX: %f     deltaY: %f       ",deltaX,deltaY);
    pc.printf("posX: %f     posY:%f      \n\r",posX,posY);              
}

void incTicksR()
{
    ticksR++;
    tickDistR++;
}

void incTicksL()
{
    ticksL++;
    tickDistL++;
}

int main() 
{
    char cmd;
    timestamp.start(); 
    angle = 0.0f;
    //Calibrate the IMU
    if (!imu.begin()) {
        pc.printf("Failed to communicate with LSM9DS1.\n");
    }
    imu.calibrate();
    imu.calibrateMag(0);
    // Initialize hall-effect control
    Sampler.attach(&sampleEncoder, 0.2); //Sampler uses sampleEncoder function every 200ms
    EncL.mode(PullUp); // Use internal pullups
    EncR.mode(PullUp);
    EncR.rise(&incTicksR);
    EncL.rise(&incTicksL);
    nav.attach(&updatePos,1);//Update X,Y,H every second
    while(1) 
    {
        //Check if char is ready to be read and put into command buffer;
        if(bt.getc() =='!')
        {
            cmd = bt.getc();
            switch (cmd)
            {
                case 'B':
                pc.printf("Got Command B!\n\r");
                break;
                
                case 'S': //Stop moving
                pc.printf("Got Command STOP!\n\r");
                tracking = 0; //Turn off wheel feedback updates
                speedL = 0;
                speedR = 0;
                lwheel.speed(0);
                rwheel.speed(0);
                break;
                
                case 'F': //Forward
                pc.printf("Got Command FORWARD!\n\r");
                dirL = 1;
                dirR = 1;
                speedL = 0.9f;
                speedR = 0.9f;
                rwheel.speed(speedR);
                lwheel.speed(speedL);
                tracking = 1; //Turn on wheel feedback updates
                tickDistL = 0; //Reset the distance ticks.
                tickDistR = 0;
                break;
                
                case 'R': //Reverse
                pc.printf("Got Command REVERSE!\n\r");
                dirL = -1;
                dirR = -1;
                speedL = -0.9f;
                speedR = -0.9f;
                rwheel.speed(speedR);
                lwheel.speed(speedL);
                tracking = 1;
                tickDistL = 0; //Reset the distance ticks.
                tickDistR = 0;
                break;
                
                case 'P': //Sweep
                pc.printf("Got Command SWEEP!\n\r");
                sweep();
                break;
                
                default:
                pc.printf("Unknown Command!\n\r");
                break;
                
            }
        }
    }
}