Adds an option to disable print job timer auto start

Marlin/Configuration.h

@@ -755,6 +755,19 @@ const bool Z_MIN_PROBE_ENDSTOP_INVERTING = false; // set to true to invert the l
 #define ABS_PREHEAT_HPB_TEMP 110
 #define ABS_PREHEAT_FAN_SPEED 0   // Insert Value between 0 and 255
 
+//
+// Print job timer
+//
+// This options allows you configure if the print job timer should automatically
+// start and stop counting when a M104 or M109 is received.
+//
+// If disabled you can control the print timer start and stop using the
+// following G-Code list:
+//
+// - M75  - Start the print job timer
+// - M76  - Pause the print job timer
+// - M77  - Stop the print job timer
+#defined PRINTJOB_TIMER_AUTOSTART
 
 //
 // Print Counter

Marlin/Marlin_main.cpp

@@ -4248,23 +4248,17 @@ inline void gcode_M42() {
 /**
  * M75: Start print timer
  */
-inline void gcode_M75() {
+inline void gcode_M75() { print_job_timer.start(); }
-  print_job_timer.start();
-}
 
 /**
  * M76: Pause print timer
  */
-inline void gcode_M76() {
+inline void gcode_M76() { print_job_timer.pause(); }
-  print_job_timer.pause();
-}
 
 /**
  * M77: Stop print timer
  */
-inline void gcode_M77() {
+inline void gcode_M77() { print_job_timer.stop(); }
-  print_job_timer.stop();
-}
 
 #if ENABLED(PRINTCOUNTER)
   /*+
@@ -4293,6 +4287,7 @@ inline void gcode_M104() {
         thermalManager.setTargetHotend(temp == 0.0 ? 0.0 : temp + duplicate_extruder_temp_offset, 1);
     #endif
 
+    #if ENABLED(PRINTJOB_TIMER_AUTOSTART)
       /**
        * We use half EXTRUDE_MINTEMP here to allow nozzles to be put into hot
        * stand by mode, for instance in a dual extruder setup, without affecting
@@ -4308,6 +4303,7 @@ inline void gcode_M104() {
        * will not restart.
        */
       else print_job_timer.start();
+    #endif
 
     if (temp > thermalManager.degHotend(target_extruder)) LCD_MESSAGEPGM(MSG_HEATING);
   }
@@ -4446,6 +4442,7 @@ inline void gcode_M109() {
         thermalManager.setTargetHotend(temp == 0.0 ? 0.0 : temp + duplicate_extruder_temp_offset, 1);
     #endif
 
+    #if ENABLED(PRINTJOB_TIMER_AUTOSTART)
       /**
        * We use half EXTRUDE_MINTEMP here to allow nozzles to be put into hot
        * stand by mode, for instance in a dual extruder setup, without affecting
@@ -4461,6 +4458,7 @@ inline void gcode_M109() {
        * will not restart.
        */
       else print_job_timer.start();
+    #endif
 
     if (temp > thermalManager.degHotend(target_extruder)) LCD_MESSAGEPGM(MSG_HEATING);
   }