Help Understanding This Program

beware: if frustrated overambitious newbies not continue.


can please explain code top bottom? written this guy. includes these libraries:


pid
lmotorcontroller
i2cdev
mpu6050


please explain reason every line being there in simpler terms already.


here is:
(it self-balancing robot)

code: [select]

#include <pid_v1.h>
#include <lmotorcontroller.h>
#include "i2cdev.h"
#include "mpu6050_6axis_motionapps20.h"

#if i2cdev_implementation == i2cdev_arduino_wire
 #include "wire.h"
#endif

#define min_abs_speed 30

mpu6050 mpu;

// mpu control/status vars
bool dmpready = false; // set true if dmp init successful
uint8_t mpuintstatus; // holds actual interrupt status byte mpu
uint8_t devstatus; // return status after each device operation (0 = success, !0 = error)
uint16_t packetsize; // expected dmp packet size (default 42 bytes)
uint16_t fifocount; // count of bytes in fifo
uint8_t fifobuffer[64]; // fifo storage buffer

// orientation/motion vars
quaternion q; // [w, x, y, z] quaternion container
vectorfloat gravity; // [x, y, z] gravity vector
float ypr[3]; // [yaw, pitch, roll] yaw/pitch/roll container , gravity vector

//pid
double originalsetpoint = 172.50;
double setpoint = originalsetpoint;
double movingangleoffset = 0.1;
double input, output;

//adjust these values fit own design
double kp = 60;   
double kd = 2.2;
double ki = 270;
pid pid(&input, &output, &setpoint, kp, ki, kd, direct);

double motorspeedfactorleft = 0.6;
double motorspeedfactorright = 0.5;

//motor controller
int ena = 5;
int in1 = 6;
int in2 = 7;
int in3 = 9;
int in4 = 8;
int enb = 10;
lmotorcontroller motorcontroller(ena, in1, in2, enb, in3, in4, motorspeedfactorleft, motorspeedfactorright);

volatile bool mpuinterrupt = false; // indicates whether mpu interrupt pin has gone high
void dmpdataready()
{
 mpuinterrupt = true;
}


void setup()
{
 // join i2c bus (i2cdev library doesn't automatically)
 #if i2cdev_implementation == i2cdev_arduino_wire
 wire.begin();
 twbr = 24; // 400khz i2c clock (200khz if cpu 8mhz)
 #elif i2cdev_implementation == i2cdev_builtin_fastwire
 fastwire::setup(400, true);
 #endif

 mpu.initialize();

 devstatus = mpu.dmpinitialize();

 // supply own gyro offsets here, scaled min sensitivity
 mpu.setxgyrooffset(220);
 mpu.setygyrooffset(76);
 mpu.setzgyrooffset(-85);
 mpu.setzacceloffset(1788); // 1688 factory default test chip

 // make sure worked (returns 0 if so)
 if (devstatus == 0)
 {
 // turn on dmp, it's ready
 mpu.setdmpenabled(true);

 // enable arduino interrupt detection
 attachinterrupt(0, dmpdataready, rising);
 mpuintstatus = mpu.getintstatus();

 // set our dmp ready flag main loop() function knows it's okay use it
 dmpready = true;

 // expected dmp packet size later comparison
 packetsize = mpu.dmpgetfifopacketsize();
 
 //setup pid
 pid.setmode(automatic);
 pid.setsampletime(10);
 pid.setoutputlimits(-255, 255);
 }
 else
 {
 // error!
 // 1 = initial memory load failed
 // 2 = dmp configuration updates failed
 // (if it's going break, code 1)
 serial.print(f("dmp initialization failed (code "));
 serial.print(devstatus);
 serial.println(f(")"));
 }
}


void loop()
{
 // if programming failed, don't try anything
 if (!dmpready) return;

 // wait mpu interrupt or packet(s) available
 while (!mpuinterrupt && fifocount < packetsize)
 {
 //no mpu data - performing pid calculations , output motors
 pid.compute();
 motorcontroller.move(output, min_abs_speed);
 
 }

 // reset interrupt flag , int_status byte
 mpuinterrupt = false;
 mpuintstatus = mpu.getintstatus();

 // current fifo count
 fifocount = mpu.getfifocount();

 // check overflow (this should never happen unless our code inefficient)
 if ((mpuintstatus & 0x10) || fifocount == 1024)
 {
 // reset can continue cleanly
 mpu.resetfifo();
 serial.println(f("fifo overflow!"));

 // otherwise, check dmp data ready interrupt (this should happen frequently)
 }
 else if (mpuintstatus & 0x02)
 {
 // wait correct available data length, should short wait
 while (fifocount < packetsize) fifocount = mpu.getfifocount();

 // read packet fifo
 mpu.getfifobytes(fifobuffer, packetsize);
 
 // track fifo count here in case there > 1 packet available
 // (this lets read more without waiting interrupt)
 fifocount -= packetsize;

 mpu.dmpgetquaternion(&q, fifobuffer);
 mpu.dmpgetgravity(&gravity, &q);
 mpu.dmpgetyawpitchroll(ypr, &q, &gravity);
 input = ypr[1] * 180/m_pi + 180;
 }
}

which lines don't understand?

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