fan measurements fix: keep fanSpeedSoftPwm = 255 during measurements, selftest changes

Firmware/planner.cpp

@@ -545,7 +545,12 @@ void check_axes_activity()
     }
   #endif//FAN_KICKSTART_TIME
   #ifdef FAN_SOFT_PWM
-  fanSpeedSoftPwm = tail_fan_speed;
+	if (fan_measuring) { //if measurement is currently in process, fanSpeedSoftPwm must remain set to 255, but we must update fanSpeedBckp value
+		fanSpeedBckp = tail_fan_speed;
+	}
+	else {
+		fanSpeedSoftPwm = tail_fan_speed;
+	}
   //printf_P(PSTR("fanspeedsoftPWM %d \n"), fanSpeedSoftPwm);
   #else
   analogWrite(FAN_PIN,tail_fan_speed);

Firmware/temperature.cpp

@@ -759,7 +759,9 @@ void manage_heater()
   if ((_millis() - extruder_autofan_last_check > FAN_CHECK_PERIOD) && (!fan_measuring)) {
 	  extruder_autofan_last_check = _millis();
 	  fanSpeedBckp = fanSpeedSoftPwm;
-	  if (fanSpeedSoftPwm > MIN_PRINT_FAN_SPEED) {
+	  
+	  if (fanSpeedSoftPwm >= MIN_PRINT_FAN_SPEED) { //if we are in rage where we are doing fan check, set full PWM range for a short time to measure fan RPM by reading tacho signal without modulation by PWM signal
+		//  printf_P(PSTR("fanSpeedSoftPwm 1: %d\n"), fanSpeedSoftPwm);
 		  fanSpeedSoftPwm = 255;
 	  }
 	  fan_measuring = true;
@@ -767,8 +769,9 @@ void manage_heater()
   if ((_millis() - extruder_autofan_last_check > FAN_CHECK_DURATION) && (fan_measuring)) {
 	  countFanSpeed();
 	  checkFanSpeed();
+	  //printf_P(PSTR("fanSpeedSoftPwm 1: %d\n"), fanSpeedSoftPwm);
 	  fanSpeedSoftPwm = fanSpeedBckp;
-	  printf_P(PSTR("fan PWM: %d; extr fanSpeed measured: %d; print fan speed measured: %d \n"), fanSpeedBckp, fan_speed[0], fan_speed[1]);
+	  //printf_P(PSTR("fan PWM: %d; extr fanSpeed measured: %d; print fan speed measured: %d \n"), fanSpeedBckp, fan_speed[0], fan_speed[1]);
 	  extruder_autofan_last_check = _millis();
 	  fan_measuring = false;
   }

Firmware/ultralcd.cpp

@@ -7372,9 +7372,11 @@ static bool lcd_selftest_fan_dialog(int _fan)
 
 	case 1:
 		//will it work with Thotend > 50 C ?
-#ifdef FAN_SOFT_PWM
-		extruder_autofan_last_check = _millis();
-		fanSpeed = 255;				
+#ifdef FAN_SOFT_PWM		
+		fanSpeed = 255;	
+		fanSpeedSoftPwm = 255;	
+		extruder_autofan_last_check = _millis(); //store time when measurement starts
+		fan_measuring = true; //start fan measuring, rest is on manage_heater
 #else //FAN_SOFT_PWM
 		fanSpeed = 150;				//print fan
 #endif //FAN_SOFT_PWM
@@ -7387,8 +7389,8 @@ static bool lcd_selftest_fan_dialog(int _fan)
 			lcd_print("|");
 		}
 #ifdef FAN_SOFT_PWM
-		countFanSpeed();
 		fanSpeed = 0;
+		fanSpeedSoftPwm = 0;	
 #else //FAN_SOFT_PWM
 		fanSpeed = 0;
 		manage_heater();			//turn off fan