code ported to olimexino STM32

i forgot to upload this, with small modification, only for serialUSB, the code work on olimexino 72mhz platform

STM32_olimexino_stepper_motor_emulator

@@ -0,0 +1,175 @@
+/* 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 SerialUSB 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
+#define encoder0PinB  4
+
+#define SpeedPin     9
+#define DirectionPin 8
+
+//from ramps 1.4 stepper driver
+#define STEP_PIN              3
+#define DIR_PIN               12
+#define ENABLE_PIN            13
+
+
+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() { 
+
+  pinMode(encoder0PinA, INPUT); 
+  pinMode(encoder0PinB, INPUT);  
+
+  pinMode(DirectionPin, OUTPUT); 
+  pinMode(SpeedPin, OUTPUT);
+
+  //ramps 1.4 motor control
+    pinMode(STEP_PIN, INPUT);
+    pinMode(DIR_PIN, INPUT);
+
+  attachInterrupt(2, doEncoderMotor0, CHANGE);  // encoder pin on interrupt 0 - pin 2
+  attachInterrupt(3, countStep, RISING);  //on pin 3
+
+  SerialUSB.println("start");                // a personal quirk
+
+} 
+
+void loop(){
+
+  while (SerialUSB.available() > 0) {
+    KP = SerialUSB.read();
+    KD = SerialUSB.read();
+    KI = SerialUSB.read();
+
+
+    SerialUSB.println(KP);
+    SerialUSB.println(KD);
+    SerialUSB.println(KI);
+}
+
+  if(millis() - previousTarget > 500){ //enable this code only for test purposes
+  SerialUSB.print(encoder0Pos);
+  SerialUSB.print(',');
+  SerialUSB.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){
+      digitalWrite ( DirectionPin ,HIGH );      
+    }
+    if(ms < 0){
+      digitalWrite ( DirectionPin , LOW );     
+      ms = -1 * ms;
+    }
+
+    int motorspeed = map(ms,0,amp,0,255);
+   if( motorspeed >= 255) motorspeed=255;
+    //analogWrite ( SpeedPin, (255 - motorSpeed) );
+    analogWrite ( SpeedPin,  motorspeed );
+    //SerialUSB.print ( ms );
+    //SerialUSB.print ( ',' );
+    //SerialUSB.println ( motorspeed );
+  }  
+}
+
+void doEncoderMotor0(){
+  if (digitalRead(encoder0PinA) == HIGH) {   // found a low-to-high on channel A
+    if (digitalRead(encoder0PinB) == LOW) {  // check channel B to see which way
+                                             // encoder is turning
+      encoder0Pos = encoder0Pos - 1;         // CCW
+    } 
+    else {
+      encoder0Pos = encoder0Pos + 1;         // CW
+    }
+  }
+  else                                        // found a high-to-low on channel A
+  { 
+    if (digitalRead(encoder0PinB) == LOW) {   // check channel B to see which way
+                                              // encoder is turning  
+      encoder0Pos = encoder0Pos + 1;          // CW
+    } 
+    else {
+      encoder0Pos = encoder0Pos - 1;          // CCW
+    }
+
+  }
+
+}
+
+void countStep(){
+  dir = digitalRead(DIR_PIN);
+            if (dir) target1++;
+            else target1--;
+}