Merge pull request #5259 from Sebastianv650/Allow_UART-ISR_inside_Stepper

Allow UART ISRs inside the stepper ISR

Marlin/stepper.cpp

 ISR(TIMER1_COMPA_vect) { Stepper::isr(); }
 
 void Stepper::isr() {
+  //Disable Timer0 ISRs and enable global ISR again to capture UART events (incoming chars)
+  #if ENABLED(ADVANCE) || ENABLED(LIN_ADVANCE)
+    CBI(TIMSK0, OCIE0A); //estepper ISR
+  #endif
+  CBI(TIMSK0, OCIE0B); //Temperature ISR
+  DISABLE_STEPPER_DRIVER_INTERRUPT();
+  sei();
+  
   if (cleaning_buffer_counter) {
     --cleaning_buffer_counter;
     current_block = NULL;
       if (!cleaning_buffer_counter && (SD_FINISHED_STEPPERRELEASE)) enqueue_and_echo_commands_P(PSTR(SD_FINISHED_RELEASECOMMAND));
     #endif
     OCR1A = 200; // Run at max speed - 10 KHz
+    //re-enable ISRs
+    #if ENABLED(ADVANCE) || ENABLED(LIN_ADVANCE)
+      SBI(TIMSK0, OCIE0A);
+    #endif
+    SBI(TIMSK0, OCIE0B);
+    ENABLE_STEPPER_DRIVER_INTERRUPT();
     return;
   }
 
         if (current_block->steps[Z_AXIS] > 0) {
           enable_z();
           OCR1A = 2000; // Run at slow speed - 1 KHz
+          #if ENABLED(ADVANCE) || ENABLED(LIN_ADVANCE)
+            SBI(TIMSK0, OCIE0A);
+          #endif
+          SBI(TIMSK0, OCIE0B);
+          ENABLE_STEPPER_DRIVER_INTERRUPT();
           return;
         }
       #endif
     }
     else {
       OCR1A = 2000; // Run at slow speed - 1 KHz
+      #if ENABLED(ADVANCE) || ENABLED(LIN_ADVANCE)
+        SBI(TIMSK0, OCIE0A);
+      #endif
+      SBI(TIMSK0, OCIE0B);
+      ENABLE_STEPPER_DRIVER_INTERRUPT();
       return;
     }
   }
   // Take multiple steps per interrupt (For high speed moves)
   bool all_steps_done = false;
   for (int8_t i = 0; i < step_loops; i++) {
-    #ifndef USBCON
-      customizedSerial.checkRx(); // Check for serial chars.
-    #endif
-
     #if ENABLED(LIN_ADVANCE)
 
       counter_E += current_block->steps[E_AXIS];
     current_block = NULL;
     planner.discard_current_block();
   }
+  #if ENABLED(ADVANCE) || ENABLED(LIN_ADVANCE)
+    SBI(TIMSK0, OCIE0A);
+  #endif
+  SBI(TIMSK0, OCIE0B);
+  ENABLE_STEPPER_DRIVER_INTERRUPT();
 }
 
 #if ENABLED(ADVANCE) || ENABLED(LIN_ADVANCE)

Marlin/temperature.cpp

 ISR(TIMER0_COMPB_vect) { Temperature::isr(); }
 
 void Temperature::isr() {
+  //Allow UART and stepper ISRs
+  CBI(TIMSK0, OCIE0B); //Disable Temperature ISR
+  sei();
 
   static uint8_t temp_count = 0;
   static TempState temp_state = StartupDelay;
       if (!endstop_monitor_count) endstop_monitor();  // report changes in endstop status
     }
   #endif
+  
+  SBI(TIMSK0, OCIE0B); //re-enable Temperature ISR
 }