danithebest91_ServoStrap/Arduino_stepper_motor_emulator_v1.0.1_direct_port_manipulation.pde
#include <digitalWriteFast.h>

/* i have made this code for the LMD18245 motor controller, 
  i have merged the pid code of  Josh Kopel 
    whith the code of makerbot servo-controller board,
  you can use this code on the some board changing some values.
  Daniele Poddighe

   external ardware require a quadrature encoder, timing slit strip and a dc motor,
   all you can find inside an old printer, i have took it from canon and hp printers(psc1510)
   
   for motor controll you can choose different type of H-bridge, i have used LMD18245,
   you can order 3 of it on ti.com sample request, the hardware needed is explained on the datasheet but i'm drowing
   the schematic and PCB layout on eagle.
   
   
   read a rotary encoder with interrupts
   Encoder hooked up with common to GROUND,
   encoder0PinA to pin 2, encoder0PinB to pin 4 (or pin 3 see below)
   it doesn't matter which encoder pin you use for A or B 
   
   is possible to change PID costants by sending on serial interfaces the values separated by ',' in this order: KP,KD,KI
   example: 5.2,3.1,0 so we have  KP=5.2 KD=3.1 KI=0 is only for testing purposes, but i will leave this function with eeprom storage

*/ 

#define encoder0PinA  2 // PD2; 
#define encoder0PinB  8  // PB0;

#define SpeedPin     6
#define DirectionPin 15 //PC1;

//from ramps 1.4 stepper driver
#define STEP_PIN              3  //PD3;
#define DIR_PIN               14 //PC0;
//#define ENABLE_PIN            13 //PB5; for now is USELESS

//to use current motor as speed control, the LMD18245 has 4 bit cuttent output
//#define  M0 9   //assign 4 bit from PORTB register to current control -> Bxx0000x (x mean any)
//#define  M1 10  // PB1; PB2; PB3; PB4
//#define  M2 11
//#define  M3 12


volatile long encoder0Pos = 0;

long target = 0;
long target1 = 0;
int amp=212;
//correction = Kp * error + Kd * (error - prevError) + kI * (sum of errors)
//PID controller constants
float KP = 6.0 ; //position multiplier (gain) 2.25
float KI = 0.1; // Intergral multiplier (gain) .25
float KD = 1.3; // derivative multiplier (gain) 1.0

int lastError = 0;
int sumError = 0;

//Integral term min/max (random value and not yet tested/verified)
int iMax = 100;
int iMin = 0;

long previousTarget = 0;
long previousMillis = 0;        // will store last time LED was updated
long interval = 5;           // interval at which to blink (milliseconds)

//for motor control ramps 1.4
bool newStep = false;
bool oldStep = false;
bool dir = false;

void setup() { 
  pinModeFast(2, INPUT);
  pinModeFast(encoder0PinA, INPUT); 
  pinModeFast(encoder0PinB, INPUT);  
  
  pinModeFast(DirectionPin, OUTPUT); 
  //pinMode(SpeedPin, OUTPUT);
  
  //ramps 1.4 motor control
    pinModeFast(STEP_PIN, INPUT);
    pinModeFast(DIR_PIN, INPUT);
    //pinModeFast(M0,OUTPUT);
    //pinModeFast(M1,OUTPUT);
    //pinModeFast(M2,OUTPUT);
    //pinModeFast(M3,OUTPUT);

  attachInterrupt(0, doEncoderMotor0, CHANGE);  // encoder pin on interrupt 0 - pin 2
  attachInterrupt(1, countStep, RISING);  //on pin 3
  
  Serial.begin (115200);
  Serial.println("start");                // a personal quirk

} 

void loop(){
  
  while (Serial.available() > 0) {
    KP = Serial.parseFloat();
    KD = Serial.parseFloat();
    KI = Serial.parseFloat();
    
    
    Serial.println(KP);
    Serial.println(KD);
    Serial.println(KI);
}
  
  if(millis() - previousTarget > 1000){ //enable this code only for test purposes because it loss a lot of time
  Serial.print(encoder0Pos);
  Serial.print(',');
  Serial.println(target1);
  previousTarget=millis();
  }
        
  target = target1;
  docalc();
}

void docalc() {
  
  if (millis() - previousMillis > interval) 
  {
    previousMillis = millis();   // remember the last time we blinked the LED
    
    long error = encoder0Pos - target ; // find the error term of current position - target    
    
    //generalized PID formula
    //correction = Kp * error + Kd * (error - prevError) + kI * (sum of errors)
    long ms = KP * error + KD * (error - lastError) +KI * (sumError);
       
    lastError = error;    
    sumError += error;
    
    //scale the sum for the integral term
    if(sumError > iMax) {
      sumError = iMax;
    } else if(sumError < iMin){
      sumError = iMin;
    }
    
    if(ms > 0){
      PORTC |=B00000010;  //digitalWriteFast2 ( DirectionPin ,HIGH );    write PC1 HIGH
    }
    if(ms < 0){
      PORTC &=(B11111101);    //digitalWriteFast2 ( DirectionPin , LOW );  write PC1 LOW
      ms = -1 * ms;
    }

    int motorspeed = map(ms,0,amp,0,255);
   if( motorspeed >= 255) motorspeed=255;
   //PORTB |=(motorspeed<<1); // is a sort of: digitalwrite(M0 M1 M2 M3, 0 0 0 0 to 1 1 1 1); it set directly PORTB to B**M3M2M1M0*; 
    //analogWrite ( SpeedPin, (255 - motorSpeed) );
    analogWrite ( SpeedPin,  motorspeed );
    //Serial.print ( ms );
    //Serial.print ( ',' );
    //Serial.println ( motorspeed );
  }  
}

void doEncoderMotor0(){
  if (((PIND&B0000100)>>2) == HIGH) {   // found a low-to-high on channel A; if(digitalRead(encoderPinA)==HIGH){.... read PB0
                                        // because PD0is used for serial, i will change in the stable version TO USE PD2
    if ((PINB&B0000001) == LOW) {  // check channel B to see which way; if(digitalRead(encoderPinB)==LOW){.... read PB0
                                             // encoder is turning
      encoder0Pos-- ;         // CCW
    } 
    else {
      encoder0Pos++ ;         // CW
    }
  }
  else                                        // found a high-to-low on channel A
  { 
    if ((PINB&B0000001) == LOW) {   // check channel B to see which way; if(digitalRead(encoderPinB)==LOW){.... read PB0
                                              // encoder is turning  
      encoder0Pos++ ;          // CW
    } 
    else {
      encoder0Pos-- ;          // CCW
    }

  }
 
}

void countStep(){
  dir = (PINC&B0000001);  // dir=digitalRead(dir_pin) read PC0, 14 digital; 
                                  //here will be (PINB&B0000001) to not use shift in the stable version
            if (dir) target1++;
            else target1--;
}
