Adds support for M114 gcode command

[new] Reports current work position when M114 command is sent

grbl/config.h

@@ -168,6 +168,9 @@
 // NOTE: The M8 flood coolant control pin on analog pin 3 will still be functional regardless.
 // #define ENABLE_M7 // Disabled by default. Uncomment to enable.
 
+// Enables reporting positions in response to the M114 GCode command
+// #define ENABLE_M114 // Disabled by default. Uncomment to enable.
+
 // This option causes the feed hold input to act as a safety door switch. A safety door, when triggered,
 // immediately forces a feed hold and then safely de-energizes the machine. Resuming is blocked until
 // the safety door is re-engaged. When it is, Grbl will re-energize the machine and then resume on the

grbl/gcode.c

@@ -280,6 +280,11 @@ uint8_t gc_execute_line(char *line)
               gc_block.modal.override = OVERRIDE_PARKING_MOTION;
               break;
           #endif
+          #ifdef ENABLE_M114
+            case 114:
+              report_realtime_position();
+              break;
+          #endif
           default: FAIL(STATUS_GCODE_UNSUPPORTED_COMMAND); // [Unsupported M command]
         }
 

grbl/report.c

@@ -643,3 +643,33 @@ void report_realtime_status()
 
   }
 #endif
+
+#ifdef ENABLE_M114
+  // Reports the current work position
+  void report_realtime_position()
+  {
+    int32_t current_position[N_AXIS]; // Copy current state of the system position variable
+    memcpy(current_position,sys_position,sizeof(sys_position));
+    float print_position[N_AXIS];
+    system_convert_array_steps_to_mpos(print_position,current_position);
+
+    float wco[N_AXIS];
+    uint8_t idx;
+    for (idx=0; idx<N_AXIS; idx++) {
+      if (idx == 0) { printPgmString(PSTR("X:")); }
+      if (idx == 1) { printPgmString(PSTR("Y:")); }
+      if (idx == 2) { printPgmString(PSTR("Z:")); }
+
+      // Apply work coordinate offsets and tool length offset to current position.
+      wco[idx] = gc_state.coord_system[idx]+gc_state.coord_offset[idx];
+      if (idx == TOOL_LENGTH_OFFSET_AXIS) { wco[idx] += gc_state.tool_length_offset; }
+      print_position[idx] -= wco[idx];
+
+      printFloat_CoordValue(print_position[idx]);
+
+      if (idx < (N_AXIS-1)) { serial_write(' '); }
+    }
+
+    report_util_line_feed();
+  }
+#endif

grbl/report.h

@@ -108,6 +108,11 @@ void report_echo_line_received(char *line);
 // Prints realtime status report
 void report_realtime_status();
 
+#ifdef ENABLE_M114
+  // Prints realtime position report
+  void report_realtime_position();
+#endif
+
 // Prints recorded probe position
 void report_probe_parameters();