Clean up GCode command short comments

Marlin/Marlin_main.cpp

 
   /**
    * M209: Enable automatic retract (M209 S1)
-   *       detect if the slicer did not support G10/11: every normal extrude-only move will be classified as retract depending on the direction.
+   *   For slicers that don't support G10/11, reversed extrude-only
+   *   moves will be classified as retraction.
    */
   inline void gcode_M209() {
     if (code_seen('S')) {
 
     case 'M': switch (codenum) {
       #if ENABLED(ULTIPANEL) || ENABLED(EMERGENCY_PARSER)
-        case 0: // M0 - Unconditional stop - Wait for user button press on LCD
-        case 1: // M1 - Conditional stop - Wait for user button press on LCD
+        case 0: // M0: Unconditional stop - Wait for user button press on LCD
+        case 1: // M1: Conditional stop - Wait for user button press on LCD
           gcode_M0_M1();
           break;
       #endif // ULTIPANEL
 
-      case 17:
+      case 17: // M17: Enable all stepper motors
         gcode_M17();
         break;
 
       #if ENABLED(SDSUPPORT)
-        case 20: // M20 - list SD card
+        case 20: // M20: list SD card
           gcode_M20(); break;
-        case 21: // M21 - init SD card
+        case 21: // M21: init SD card
           gcode_M21(); break;
-        case 22: //M22 - release SD card
+        case 22: // M22: release SD card
           gcode_M22(); break;
-        case 23: //M23 - Select file
+        case 23: // M23: Select file
           gcode_M23(); break;
-        case 24: //M24 - Start SD print
+        case 24: // M24: Start SD print
           gcode_M24(); break;
-        case 25: //M25 - Pause SD print
+        case 25: // M25: Pause SD print
           gcode_M25(); break;
-        case 26: //M26 - Set SD index
+        case 26: // M26: Set SD index
           gcode_M26(); break;
-        case 27: //M27 - Get SD status
+        case 27: // M27: Get SD status
           gcode_M27(); break;
-        case 28: //M28 - Start SD write
+        case 28: // M28: Start SD write
           gcode_M28(); break;
-        case 29: //M29 - Stop SD write
+        case 29: // M29: Stop SD write
           gcode_M29(); break;
-        case 30: //M30 <filename> Delete File
+        case 30: // M30 <filename> Delete File
           gcode_M30(); break;
-        case 32: //M32 - Select file and start SD print
+        case 32: // M32: Select file and start SD print
           gcode_M32(); break;
 
         #if ENABLED(LONG_FILENAME_HOST_SUPPORT)
-          case 33: //M33 - Get the long full path to a file or folder
+          case 33: // M33: Get the long full path to a file or folder
             gcode_M33(); break;
-        #endif // LONG_FILENAME_HOST_SUPPORT
+        #endif
 
-        case 928: //M928 - Start SD write
+        case 928: // M928: Start SD write
           gcode_M928(); break;
       #endif //SDSUPPORT
 
-      case 31: //M31 take time since the start of the SD print or an M109 command
-        gcode_M31();
-        break;
+      case 31: // M31: Report time since the start of SD print or last M109
+        gcode_M31(); break;
 
       case 42: //M42 -Change pin status via gcode
         gcode_M42();
         break;
 
       #if ENABLED(Z_MIN_PROBE_REPEATABILITY_TEST)
-        case 48: // M48 Z probe repeatability
+        case 48: // M48: Z probe repeatability test
           gcode_M48();
           break;
       #endif // Z_MIN_PROBE_REPEATABILITY_TEST
 
-      case 75: // Start print timer
-        gcode_M75();
-        break;
-
-      case 76: // Pause print timer
-        gcode_M76();
-        break;
-
-      case 77: // Stop print timer
-        gcode_M77();
-        break;
+      case 75: // M75: Start print timer
+        gcode_M75(); break;
+      case 76: // M76: Pause print timer
+        gcode_M76(); break;
+      case 77: // M77: Stop print timer
+        gcode_M77(); break;
 
       #if ENABLED(PRINTCOUNTER)
-        case 78: // Show print statistics
-          gcode_M78();
-          break;
+        case 78: // M78: Show print statistics
+          gcode_M78(); break;
       #endif
 
       #if ENABLED(M100_FREE_MEMORY_WATCHER)
-        case 100:
+        case 100: // M100: Free Memory Report
           gcode_M100();
           break;
       #endif
 
-      case 104: // M104
+      case 104: // M104: Set hot end temperature
         gcode_M104();
         break;
 
           break;
       #endif
 
-      case 140: // M140: Set bed temp
+      case 140: // M140: Set bed temperature
         gcode_M140();
         break;
 
-      case 105: // M105: Read current temperature
+      case 105: // M105: Report current temperature
         gcode_M105();
         KEEPALIVE_STATE(NOT_BUSY);
         return; // "ok" already printed
 
-      case 109: // M109: Wait for temperature
+      case 109: // M109: Wait for hotend temperature to reach target
         gcode_M109();
         break;
 
       #if HAS_TEMP_BED
-        case 190: // M190: Wait for bed heater to reach target
+        case 190: // M190: Wait for bed temperature to reach target
           gcode_M190();
           break;
       #endif // HAS_TEMP_BED
         gcode_M81();
         break;
 
-      case 82:
+      case 82: // M83: Set E axis normal mode (same as other axes)
         gcode_M82();
         break;
-      case 83:
+      case 83: // M83: Set E axis relative mode
         gcode_M83();
         break;
-      case 18: // (for compatibility)
-      case 84: // M84
+      case 18: // M18 => M84
+      case 84: // M84: Disable all steppers or set timeout
         gcode_M18_M84();
         break;
-      case 85: // M85
+      case 85: // M85: Set inactivity stepper shutdown timeout
         gcode_M85();
         break;
       case 92: // M92: Set the steps-per-unit for one or more axes
       #endif
 
       #if ENABLED(TEMPERATURE_UNITS_SUPPORT)
-        case 149:
+        case 149: // M149: Set temperature units
           gcode_M149();
           break;
       #endif
 
       #if ENABLED(BLINKM)
 
-        case 150: // M150
+        case 150: // M150: Set the BlinkM LCD color
           gcode_M150();
           break;
 
-      #endif //BLINKM
+      #endif // BLINKM
 
       #if ENABLED(EXPERIMENTAL_I2CBUS)
 
-        case 155:
+        case 155: // M155: Send data to an i2c slave
           gcode_M155();
           break;
 
-        case 156:
+        case 156: // M156: Request data from an i2c slave
           gcode_M156();
           break;
 
       #endif //EXPERIMENTAL_I2CBUS
 
       #if ENABLED(MIXING_EXTRUDER)
-        case 163: // M163 S<int> P<float> set weight for a mixing extruder
+        case 163: // M163: Set a component weight for mixing extruder
           gcode_M163();
           break;
         #if MIXING_VIRTUAL_TOOLS > 1
-          case 164: // M164 S<int> save current mix as a virtual extruder
+          case 164: // M164: Save current mix as a virtual extruder
             gcode_M164();
             break;
         #endif
         #if ENABLED(DIRECT_MIXING_IN_G1)
-          case 165: // M165 [ABCDHI]<float> set multiple mix weights
+          case 165: // M165: Set multiple mix weights
             gcode_M165();
             break;
         #endif
       #endif
 
-      case 200: // M200 D<diameter> Set filament diameter and set E axis units to cubic. (Use S0 to revert to linear units.)
+      case 200: // M200: Set filament diameter, E to cubic units
         gcode_M200();
         break;
-      case 201: // M201
+      case 201: // M201: Set max acceleration for print moves (units/s^2)
         gcode_M201();
         break;
       #if 0 // Not used for Sprinter/grbl gen6
           gcode_M202();
           break;
       #endif
-      case 203: // M203 max feedrate units/sec
+      case 203: // M203: Set max feedrate (units/sec)
         gcode_M203();
         break;
-      case 204: // M204 acclereration S normal moves T filmanent only moves
+      case 204: // M204: Set acceleration
         gcode_M204();
         break;
-      case 205: //M205 advanced settings:  minimum travel speed S=while printing T=travel only,  B=minimum segment time X= maximum xy jerk, Z=maximum Z jerk
+      case 205: //M205: Set advanced settings
         gcode_M205();
         break;
-      case 206: // M206 additional homing offset
+      case 206: // M206: Set home offsets
         gcode_M206();
         break;
 
       #if ENABLED(DELTA)
-        case 665: // M665 set delta configurations L<diagonal_rod> R<delta_radius> S<segments_per_sec>
+        case 665: // M665: Set delta configurations
           gcode_M665();
           break;
       #endif
 
       #if ENABLED(DELTA) || ENABLED(Z_DUAL_ENDSTOPS)
-        case 666: // M666 set delta / dual endstop adjustment
+        case 666: // M666: Set delta or dual endstop adjustment
           gcode_M666();
           break;
       #endif
 
       #if ENABLED(FWRETRACT)
-        case 207: // M207 - Set Retract Length: S<length>, Feedrate: F<units/min>, and Z lift: Z<distance>
+        case 207: // M207: Set Retract Length, Feedrate, and Z lift
           gcode_M207();
           break;
-        case 208: // M208 - Set Recover (unretract) Additional (!) Length: S<length> and Feedrate: F<units/min>
+        case 208: // M208: Set Recover (unretract) Additional Length and Feedrate
           gcode_M208();
           break;
-        case 209: // M209 - Turn Automatic Retract Detection on/off: S<bool> (For slicers that don't support G10/11). Every normal extrude-only move will be classified as retract depending on the direction.
+        case 209: // M209: Turn Automatic Retract Detection on/off
           gcode_M209();
           break;
       #endif // FWRETRACT
 
-      case 211: // M211 - Enable, Disable, and/or Report software endstops
+      case 211: // M211: Enable, Disable, and/or Report software endstops
         gcode_M211();
         break;
 
       #if HOTENDS > 1
-        case 218: // M218 - Set a tool offset: T<index> X<offset> Y<offset>
+        case 218: // M218: Set a tool offset
           gcode_M218();
           break;
       #endif
 
-      case 220: // M220 - Set Feedrate Percentage: S<percent> ("FR" on your LCD)
+      case 220: // M220: Set Feedrate Percentage: S<percent> ("FR" on your LCD)
         gcode_M220();
         break;
 
-      case 221: // M221 - Set Flow Percentage: S<percent>
+      case 221: // M221: Set Flow Percentage
         gcode_M221();
         break;
 
-      case 226: // M226 P<pin number> S<pin state>- Wait until the specified pin reaches the state required
+      case 226: // M226: Wait until a pin reaches a state
         gcode_M226();
         break;
 
       #if HAS_SERVOS
-        case 280: // M280 - set servo position absolute. P: servo index, S: angle or microseconds
+        case 280: // M280: Set servo position absolute
           gcode_M280();
           break;
       #endif // HAS_SERVOS
 
       #if HAS_BUZZER
-        case 300: // M300 - Play beep tone
+        case 300: // M300: Play beep tone
           gcode_M300();
           break;
       #endif // HAS_BUZZER
 
       #if ENABLED(PIDTEMP)
-        case 301: // M301
+        case 301: // M301: Set hotend PID parameters
           gcode_M301();
           break;
       #endif // PIDTEMP
 
       #if ENABLED(PIDTEMPBED)
-        case 304: // M304
+        case 304: // M304: Set bed PID parameters
           gcode_M304();
           break;
       #endif // PIDTEMPBED
 
       #if defined(CHDK) || HAS_PHOTOGRAPH
-        case 240: // M240  Triggers a camera by emulating a Canon RC-1 : http://www.doc-diy.net/photo/rc-1_hacked/
+        case 240: // M240: Trigger a camera by emulating a Canon RC-1 : http://www.doc-diy.net/photo/rc-1_hacked/
           gcode_M240();
           break;
       #endif // CHDK || PHOTOGRAPH_PIN
 
       #if HAS_LCD_CONTRAST
-        case 250: // M250  Set LCD contrast value: C<value> (value 0..63)
+        case 250: // M250: Set LCD contrast
           gcode_M250();
           break;
       #endif // HAS_LCD_CONTRAST
 
       #if ENABLED(PREVENT_COLD_EXTRUSION)
-        case 302: // allow cold extrudes, or set the minimum extrude temperature
+        case 302: // M302: Allow cold extrudes (set the minimum extrude temperature)
           gcode_M302();
           break;
       #endif // PREVENT_COLD_EXTRUSION
 
-      case 303: // M303 PID autotune
+      case 303: // M303: PID autotune
         gcode_M303();
         break;
 
       #if ENABLED(MORGAN_SCARA)
-        case 360:  // M360 SCARA Theta pos1
+        case 360:  // M360: SCARA Theta pos1
           if (gcode_M360()) return;
           break;
-        case 361:  // M361 SCARA Theta pos2
+        case 361:  // M361: SCARA Theta pos2
           if (gcode_M361()) return;
           break;
-        case 362:  // M362 SCARA Psi pos1
+        case 362:  // M362: SCARA Psi pos1
           if (gcode_M362()) return;
           break;
-        case 363:  // M363 SCARA Psi pos2
+        case 363:  // M363: SCARA Psi pos2
           if (gcode_M363()) return;
           break;
-        case 364:  // M364 SCARA Psi pos3 (90 deg to Theta)
+        case 364:  // M364: SCARA Psi pos3 (90 deg to Theta)
           if (gcode_M364()) return;
           break;
       #endif // SCARA
 
-      case 400: // M400 finish all moves
+      case 400: // M400: Finish all moves
         gcode_M400();
         break;
 
       #if HAS_BED_PROBE
-        case 401:
+        case 401: // M401: Deploy probe
           gcode_M401();
           break;
-        case 402:
+        case 402: // M402: Stow probe
           gcode_M402();
           break;
       #endif // HAS_BED_PROBE
 
       #if ENABLED(FILAMENT_WIDTH_SENSOR)
-        case 404:  //M404 Enter the nominal filament width (3mm, 1.75mm ) N<3.0> or display nominal filament width
+        case 404:  // M404: Enter the nominal filament width (3mm, 1.75mm ) N<3.0> or display nominal filament width
           gcode_M404();
           break;
-        case 405:  //M405 Turn on filament sensor for control
+        case 405:  // M405: Turn on filament sensor for control
           gcode_M405();
           break;
-        case 406:  //M406 Turn off filament sensor for control
+        case 406:  // M406: Turn off filament sensor for control
           gcode_M406();
           break;
-        case 407:   //M407 Display measured filament diameter
+        case 407:   // M407: Display measured filament diameter
           gcode_M407();
           break;
       #endif // ENABLED(FILAMENT_WIDTH_SENSOR)
 
       #if ENABLED(MESH_BED_LEVELING)
-        case 420: // M420 Enable/Disable Mesh Bed Leveling
+        case 420: // M420: Enable/Disable Mesh Bed Leveling
           gcode_M420();
           break;
-        case 421: // M421 Set a Mesh Bed Leveling Z coordinate
+        case 421: // M421: Set a Mesh Bed Leveling Z coordinate
           gcode_M421();
           break;
       #endif
 
-      case 428: // M428 Apply current_position to home_offset
+      case 428: // M428: Apply current_position to home_offset
         gcode_M428();
         break;
 
-      case 500: // M500 Store settings in EEPROM
+      case 500: // M500: Store settings in EEPROM
         gcode_M500();
         break;
-      case 501: // M501 Read settings from EEPROM
+      case 501: // M501: Read settings from EEPROM
         gcode_M501();
         break;
-      case 502: // M502 Revert to default settings
+      case 502: // M502: Revert to default settings
         gcode_M502();
         break;
-      case 503: // M503 print settings currently in memory
+      case 503: // M503: print settings currently in memory
         gcode_M503();
         break;
 
       #endif
 
       #if HAS_BED_PROBE
-        case 851: // Set Z Probe Z Offset
+        case 851: // M851: Set Z Probe Z Offset
           gcode_M851();
           break;
       #endif // HAS_BED_PROBE
 
       #if ENABLED(FILAMENT_CHANGE_FEATURE)
-        case 600: //Pause for filament change X[pos] Y[pos] Z[relative lift] E[initial retract] L[later retract distance for removal]
+        case 600: // M600: Pause for filament change
           gcode_M600();
           break;
       #endif // FILAMENT_CHANGE_FEATURE
 
       #if ENABLED(DUAL_X_CARRIAGE)
-        case 605:
+        case 605: // M605: Set Dual X Carriage movement mode
           gcode_M605();
           break;
       #endif // DUAL_X_CARRIAGE
 
       #if ENABLED(LIN_ADVANCE)
-        case 905: // M905 Set advance factor.
+        case 905: // M905: Set advance K factor.
           gcode_M905();
           break;
       #endif
 
-      case 907: // M907 Set digital trimpot motor current using axis codes.
+      case 907: // M907: Set digital trimpot motor current using axis codes.
         gcode_M907();
         break;
 
       #if HAS_DIGIPOTSS || ENABLED(DAC_STEPPER_CURRENT)
 
-        case 908: // M908 Control digital trimpot directly.
+        case 908: // M908: Control digital trimpot directly.
           gcode_M908();
           break;
 
         #if ENABLED(DAC_STEPPER_CURRENT) // As with Printrbot RevF
 
-          case 909: // M909 Print digipot/DAC current value
+          case 909: // M909: Print digipot/DAC current value
             gcode_M909();
             break;
 
-          case 910: // M910 Commit digipot/DAC value to external EEPROM
+          case 910: // M910: Commit digipot/DAC value to external EEPROM
             gcode_M910();
             break;
 
 
       #if HAS_MICROSTEPS
 
-        case 350: // M350 Set microstepping mode. Warning: Steps per unit remains unchanged. S code sets stepping mode for all drivers.
+        case 350: // M350: Set microstepping mode. Warning: Steps per unit remains unchanged. S code sets stepping mode for all drivers.
           gcode_M350();
           break;
 
-        case 351: // M351 Toggle MS1 MS2 pins directly, S# determines MS1 or MS2, X# sets the pin high/low.
+        case 351: // M351: Toggle MS1 MS2 pins directly, S# determines MS1 or MS2, X# sets the pin high/low.
           gcode_M351();
           break;
 

Marlin/fastio.h

   #define DIO21_DDR   DDRC
   #define DIO21_PWM   NULL
 
-
-
   #undef PB0
   #define PB0_PIN     PINB0
   #define PB0_RPORT   PINB