Expanded M302 to allow setting the temp

Marlin/Marlin_main.cpp

@@ -128,7 +128,7 @@
 // M280 - set servo position absolute. P: servo index, S: angle or microseconds
 // M300 - Play beepsound S<frequency Hz> P<duration ms>
 // M301 - Set PID parameters P I and D
-// M302 - Allow cold extrudes
+// M302 - Allow cold extrudes, or set the minimum extrude S<temperature>.
 // M303 - PID relay autotune S<temperature> sets the target temperature. (default target temperature = 150C)
 // M304 - Set bed PID parameters P I and D
 // M400 - Finish all moves
@@ -1625,12 +1625,15 @@ void process_commands()
       #endif
      }
     break;
-
-    case 302: // allow cold extrudes
+    #ifdef PREVENT_DANGEROUS_EXTRUDE
+    case 302: // allow cold extrudes, or set the minimum extrude temperature
     {
-      allow_cold_extrudes(true);
+	  float temp = .0;
+	  if (code_seen('S')) temp=code_value();
+      set_extrude_min_temp(temp);
     }
     break;
+	#endif
     case 303: // M303 PID autotune
     {
       float temp = 150.0;

Marlin/planner.cpp

@@ -98,7 +98,7 @@ volatile unsigned char block_buffer_tail;           // Index of the block to pro
 //=============================private variables ============================
 //===========================================================================
 #ifdef PREVENT_DANGEROUS_EXTRUDE
-bool allow_cold_extrude=false;
+float extrude_min_temp=EXTRUDE_MINTEMP;
 #endif
 #ifdef XY_FREQUENCY_LIMIT
 #define MAX_FREQ_TIME (1000000.0/XY_FREQUENCY_LIMIT)
@@ -537,7 +537,7 @@ void plan_buffer_line(const float &x, const float &y, const float &z, const floa
   #ifdef PREVENT_DANGEROUS_EXTRUDE
   if(target[E_AXIS]!=position[E_AXIS])
   {
-    if(degHotend(active_extruder)<EXTRUDE_MINTEMP && !allow_cold_extrude)
+    if(degHotend(active_extruder)<extrude_min_temp)
     {
       position[E_AXIS]=target[E_AXIS]; //behave as if the move really took place, but ignore E part
       SERIAL_ECHO_START;
@@ -918,12 +918,12 @@ uint8_t movesplanned()
   return (block_buffer_head-block_buffer_tail + BLOCK_BUFFER_SIZE) & (BLOCK_BUFFER_SIZE - 1);
 }
 
-void allow_cold_extrudes(bool allow)
-{
 #ifdef PREVENT_DANGEROUS_EXTRUDE
-  allow_cold_extrude=allow;
-#endif
+void set_extrude_min_temp(float temp)
+{
+  extrude_min_temp=temp;
 }
+#endif
 
 // Calculate the steps/s^2 acceleration rates, based on the mm/s^s
 void reset_acceleration_rates()

Marlin/planner.h

@@ -139,7 +139,9 @@ FORCE_INLINE bool blocks_queued()
     return true;
 }
 
-void allow_cold_extrudes(bool allow);
+#ifdef PREVENT_DANGEROUS_EXTRUDE
+void set_extrude_min_temp(float temp);
+#endif
 
 void reset_acceleration_rates();
 #endif