Replacing an encoder with a magnetic sensor ( I have the code)

so goal build program robot. have rotary encoder (or potentiometer) attached wheel , every time wheel spins, friction turns encoder , calculated distance me.  but more accurate results, have since put magnet on wheel , taped sensor everytime magnet passes 1 revolution, magnetic sensor can record it.

have replaced potentiometer on wheel (controls steering) motor both motor , has encoder on top.


i have simple code lights led whenever magnet comes close. can guide me next?

code: [select]


circuit:
* potentiometer connected analog pin 0.
  center pin of potentiometer goes analog pin.
  side pins of potentiometer go +5v , ground
* "p" channel on motor driver connected digital pin 9
* "d" channel on motor driver connected digital pin 7



*/

// these constants won't change.  they're used give names
// pins used:
const int analoginpin = a0;  // analog input pin potentiometer attached to
const int analogoutpin = 9; // analog output pin "p" channel attached (pwm signal)
const int digitaloutpin = 7; // digital output pin "d" channel attached (controls motor direction)
const int pump = 10;

// pid gains
const int pgain = 3;
const int dgain = 1;
const int igain = 0.05;

// input , output variables
int sensorvalue = 0;        // value read pot
int outputvalue = 0;        // value output pwm (analog out)

// variables needed control law
double potangle = 0; // value in degrees
double prevpotangle = 0; // previous value read pot
double desiredposition = 185; // desired position (in degrees) want motor go to
double error = 0; // current error
double motorvelocity = 0; // first derivative of motorposition
double errorintegral = 0; // used in pid control law
double controlsignal = 0; // control signal sent motor
double interval = 50;
long previousmillis = 0;



// time keeping variables
int count = 0; // keeps track of time (for switching desired position)
int dt = 1; // time takes execute 1 loop (in ms)
int encoderpin1 = 2;
int encoderpin2 = 3;
int pumpstate = low;

volatile int lastencoded = 0;
volatile long encodervalue = 0;


////////////////////////stuff/to/chage/////////////////////////////////////////////

int steerangle = 217;
int distance = 330;
int brakeangle = 74;

///////////////////////////////////////////////////////////////////////////////


long lastencodervalue = 0;

int lastmsb = 0;
int lastlsb = 0;

unsigned long time;


void setup() {
 // initialize serial communications @ 9600 bps:
 serial.begin(9600); // allows write values serial monitor
 pinmode(digitaloutpin, output); // sets "d" channel pin output
 pinmode(pump, output);
 pinmode(encoderpin1, input);
 pinmode(encoderpin2, input);

 digitalwrite(encoderpin1, high); //turn pullup resistor on
 digitalwrite(encoderpin2, high); //turn pullup resistor on

 //call updateencoder() when high/low changed seen
 //on interrupt 0 (pin 2), or interrupt 1 (pin 3)
 attachinterrupt(0, updateencoder, change);
 attachinterrupt(1, updateencoder, change);
 desiredposition = 90;

}


void loop() {
 // read analog in value:
 
 sensorvalue = analogread(analoginpin);  // read integer b/w 0 , 1023 (10-bit resolution)
 
 // first save previous value
 prevpotangle = potangle;
 // save new value, mapping value in degrees:
 potangle = map(sensorvalue, 0, 1023, 0, 360);
 
 // use compute error , motor speed
 error = potangle - desiredposition;
 motorvelocity = (potangle - prevpotangle)/(dt); // (in deg/ms)
 errorintegral = errorintegral + error*(dt/1000);
 
 // calculate motor control signal using pid control law
 controlsignal = -1*pgain*error - dgain*motorvelocity - igain*errorintegral;
 
 unsigned long currentmillis = millis();
 
 
  // tell motor way spin
 if (controlsignal >= 0) {
digitalwrite(digitaloutpin, high);
 } else {
digitalwrite(digitaloutpin, low);
 }
   
 // map range of analog out:
 controlsignal = abs(controlsignal);  // can ouptut positive values
 outputvalue = constrain(controlsignal, 0, 255);  // 8-bit resolution
 
 // change analog out value:
 analogwrite(analogoutpin, outputvalue);        

  if(currentmillis - previousmillis > interval) {
   // save last time blinked led
   previousmillis = currentmillis;  

   // if led off turn on , vice-versa:
   if (pumpstate == low)
     pumpstate = high;
   else
     pumpstate = low;

   // set led ledstate of variable:
   digitalwrite(pump, pumpstate);
 }

if (encodervalue>=distance)
{
 pumpstate=low;
}

if (currentmillis>=57000)
{
 pumpstate=high;
}


 // print results serial monitor: (uncomment display)
//  serial.print("desired position = " );                      
//  serial.print(desiredposition);      
//  serial.print("\t actual position = ");      
//  serial.print(potangle);
//  serial.print("\t rotarty = ");
//  serial.println(encodervalue);  


 
 
 if (encodervalue >=distance) {
   desiredposition = brakeangle;}
   else {
     desiredposition = steerangle;
   }
   
}



void updateencoder(){
 int msb = digitalread(encoderpin1); //msb = significant bit
 int lsb = digitalread(encoderpin2); //lsb = least significant bit

 int encoded = (msb << 1) |lsb; //converting 2 pin value single number
 int sum  = (lastencoded << 2) | encoded; //adding previous encoded value

 if(sum == 0b1101 || sum == 0b0100 || sum == 0b0010 || sum == 0b1011) encodervalue ++;
 if(sum == 0b1110 || sum == 0b0111 || sum == 0b0001 || sum == 0b1000) encodervalue --;

 lastencoded = encoded; //store value next time
}

you want control movement. ?
..and replace n pulses/rev 1 pulse/rev ??
this diffucult understand!
.......................
to 'full control' - lego .. use stepper motors

Arduino Forum > Using Arduino > Sensors > Replacing an encoder with a magnetic sensor ( I have the code)

arduino