Added PID autotune. (experimental)

M303 Starts autotune. Wait till the Kp Ki and Kd constants are printed.
Put these values in Configuration.h

Marlin/Marlin.pde

@@ -109,6 +109,7 @@
 // M501 - reads parameters from EEPROM (if you need reset them after you changed them temporarily).  
 // M502 - reverts to the default "factory settings".  You still need to store them in EEPROM afterwards if you want to.
 // M503 - print the current settings (from memory not from eeprom)
+// M303 - PID relay autotune S<temperature> sets the target temperature. (default target temperature = 150C)
 
 //Stepper Movement Variables
 
@@ -1197,6 +1198,13 @@ void process_commands()
       allow_cold_extrudes(true);
     }
     break;
+    case 303: // M303 PID autotune
+    {
+      float temp = 150.0;
+      if (code_seen('S')) temp=code_value();
+      PID_autotune(temp);
+    }
+    break;
     case 400: // finish all moves
     {
       st_synchronize();

Marlin/pins.h

@@ -734,7 +734,7 @@
     #define encrot2 3
     #define encrot3 1
 
-    
+    #define SDCARDDETECT -1
     //bits in the shift register that carry the buttons for:
     // left up center down right red
     #define BL_LE 7

Marlin/temperature.cpp

@@ -62,7 +62,7 @@ int current_raw_bed = 0;
 //===========================================================================
 //=============================private variables============================
 //===========================================================================
-static bool temp_meas_ready = false;
+static volatile bool temp_meas_ready = false;
 
 static unsigned long  previous_millis_bed_heater;
 //static unsigned long previous_millis_heater;
@@ -133,6 +133,93 @@ static unsigned long  previous_millis_bed_heater;
 //=============================   functions      ============================
 //===========================================================================
 
+void PID_autotune(float temp)
+{
+  float input;
+  int cycles=0;
+  bool heating = true;
+  soft_pwm[0] = 255>>1;
+
+  unsigned long temp_millis = millis();
+  unsigned long t1=temp_millis;
+  unsigned long t2=temp_millis;
+  long t_high;
+  long t_low;
+
+  long bias=127;
+  long d = 127;
+  float Ku, Tu;
+  float Kp, Ki, Kd;
+  float max, min;
+  
+  SERIAL_ECHOLN("PID Autotune start");
+
+  for(;;) {
+
+    if(temp_meas_ready == true) { // temp sample ready
+      CRITICAL_SECTION_START;
+      temp_meas_ready = false;
+      CRITICAL_SECTION_END;
+      input = analog2temp(current_raw[0], 0);
+      
+      max=max(max,input);
+      min=min(min,input);
+      if(heating == true && input > temp) {
+        if(millis() - t2 > 5000) { 
+          heating=false;
+          soft_pwm[0] = (bias - d) >> 1;
+          t1=millis();
+          t_high=t1 - t2;
+          max=temp;
+        }
+      }
+      if(heating == false && input < temp) {
+        if(millis() - t1 > 5000) {
+          heating=true;
+          t2=millis();
+          t_low=t2 - t1;
+          if(cycles > 0) {
+            bias += (d*(t_high - t_low))/(t_low + t_high);
+            bias = constrain(bias, 20 ,235);
+            if(bias > 127) d = 254 - bias;
+            else d = bias;
+
+            SERIAL_PROTOCOLPGM(" bias: "); SERIAL_PROTOCOL(bias);
+            SERIAL_PROTOCOLPGM(" d: "); SERIAL_PROTOCOL(d);
+            SERIAL_PROTOCOLPGM(" min: "); SERIAL_PROTOCOL(min);
+            SERIAL_PROTOCOLPGM(" max: "); SERIAL_PROTOCOLLN(max);
+            if(cycles > 2) {
+              Ku = (4.0*d)/(3.14159*(max-min)/2.0);
+              Tu = ((float)(t_low + t_high)/1000.0);
+              Kp = 0.6*Ku;
+              Ki = 2*Kp/Tu;
+              Kd = Kp*Tu/8;
+              SERIAL_PROTOCOLPGM(" Kp: "); SERIAL_PROTOCOLLN(Kp);
+              SERIAL_PROTOCOLPGM(" Ki: "); SERIAL_PROTOCOLLN(Ki);
+              SERIAL_PROTOCOLPGM(" Kd: "); SERIAL_PROTOCOLLN(Kd);
+            }
+          }
+          soft_pwm[0] = (bias + d) >> 1;
+          cycles++;
+          min=temp;
+        }
+      } 
+    }
+    if(input > (temp + 20)) {
+      SERIAL_PROTOCOLLNPGM("PID Autotune failed !!!, Temperature to high");
+      return;
+    }
+    if(millis() - temp_millis > 2000) {
+      temp_millis = millis();
+      SERIAL_PROTOCOLPGM("ok T:");
+      SERIAL_PROTOCOL(degHotend(0));   
+      SERIAL_PROTOCOLPGM(" @:");
+      SERIAL_PROTOCOLLN(getHeaterPower(0));       
+    }
+    LCD_STATUS;
+  }
+}
+
 void updatePID()
 {
 #ifdef PIDTEMP

Marlin/temperature.h

@@ -158,5 +158,8 @@ FORCE_INLINE void autotempShutdown(){
  }
  #endif
 }
+
+void PID_autotune(float temp);
+
 #endif
 

Marlin/ultralcd.pde

@@ -315,19 +315,18 @@ void MainMenu::showStatus()
   static int olddegHotEnd0=-1;
   static int oldtargetHotEnd0=-1;
   //force_lcd_update=true;
-  if(force_lcd_update||feedmultiplychanged)  //initial display of content
+  if(force_lcd_update)  //initial display of content
   {
-    feedmultiplychanged=false;
     encoderpos=feedmultiply;
     clear();
-    lcd.setCursor(0,0);lcdprintPGM("\002123/567\001 ");
+    lcd.setCursor(0,0);lcdprintPGM("\002---/---\001 ");
     #if defined BED_USES_THERMISTOR || defined BED_USES_AD595 
-      lcd.setCursor(10,0);lcdprintPGM("B123/567\001 ");
+      lcd.setCursor(10,0);lcdprintPGM("B---/---\001 ");
     #endif
   }
     
   int tHotEnd0=intround(degHotend0());
-  if((abs(tHotEnd0-olddegHotEnd0)>1)||force_lcd_update) //>1 because otherwise the lcd is refreshed to often.
+  if((tHotEnd0!=olddegHotEnd0)||force_lcd_update)
   {
     lcd.setCursor(1,0);
     lcd.print(ftostr3(tHotEnd0));
@@ -379,8 +378,15 @@ void MainMenu::showStatus()
     lcdprintPGM("Z:");lcd.print(ftostr52(current_position[2]));
     oldzpos=currentz;
   }
+  
   static int oldfeedmultiply=0;
   int curfeedmultiply=feedmultiply;
+  
+  if(feedmultiplychanged == true) {
+    feedmultiplychanged == false;
+    encoderpos = curfeedmultiply;
+  }
+  
   if(encoderpos!=curfeedmultiply||force_lcd_update)
   {
    curfeedmultiply=encoderpos;
@@ -391,12 +397,14 @@ void MainMenu::showStatus()
    feedmultiply=curfeedmultiply;
    encoderpos=curfeedmultiply;
   }
+  
   if((curfeedmultiply!=oldfeedmultiply)||force_lcd_update)
   {
    oldfeedmultiply=curfeedmultiply;
    lcd.setCursor(0,2);
    lcd.print(itostr3(curfeedmultiply));lcdprintPGM("% ");
   }
+  
   if(messagetext[0]!='\0')
   {
     lcd.setCursor(0,LCD_HEIGHT-1);
@@ -404,7 +412,6 @@ void MainMenu::showStatus()
     uint8_t n=strlen(messagetext);
     for(int8_t i=0;i<LCD_WIDTH-n;i++)
       lcd.print(" ");
-    
     messagetext[0]='\0';
   }