Add support for M575 (#14757)

Marlin/Configuration_adv.h

@@ -1369,6 +1369,9 @@
   //#define SERIAL_XON_XOFF
 #endif
 
+// Add M575 G-code to change the baud rate
+//#define BAUD_RATE_GCODE
+
 #if ENABLED(SDSUPPORT)
   // Enable this option to collect and display the maximum
   // RX queue usage after transferring a file to SD.

Marlin/src/HAL/HAL_LINUX/include/serial.h

@@ -83,8 +83,9 @@ public:
 
   HalSerial() { host_connected = true; }
 
-  void begin(int32_t baud) {
-  }
+  void begin(int32_t baud) { }
+
+  void end() { }
 
   int peek() {
     uint8_t value;

Marlin/src/HAL/HAL_LPC1768/MarlinSerial.h

@@ -49,6 +49,8 @@ public:
     {
     }
 
+  void end() { }
+
   #if ENABLED(EMERGENCY_PARSER)
     bool recv_callback(const char c) override {
       emergency_parser.update(emergency_state, c);

Marlin/src/HAL/shared/Marduino.h

@@ -29,6 +29,8 @@
 #undef M_PI           // Redefined by all
 #undef _BV            // Redefined by some
 #undef sq             // Redefined by teensy3/wiring.h
+#undef SBI            // Redefined by arduino/const_functions.h
+#undef CBI            // Redefined by arduino/const_functions.h
 
 #include <Arduino.h>  // NOTE: If included earlier then this line is a NOOP
 

Marlin/src/gcode/config/M575.cpp

@@ -0,0 +1,74 @@
+/**
+ * Marlin 3D Printer Firmware
+ * Copyright (c) 2019 MarlinFirmware [https://github.com/MarlinFirmware/Marlin]
+ *
+ * Based on Sprinter and grbl.
+ * Copyright (c) 2011 Camiel Gubbels / Erik van der Zalm
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+#include "../../inc/MarlinConfig.h"
+
+#if ENABLED(BAUD_RATE_GCODE)
+
+#include "../gcode.h"
+
+/**
+ * M575 - Change serial baud rate
+ *
+ *   P<index>    - Serial port index. Omit for all.
+ *   B<baudrate> - Baud rate (bits per second)
+ */
+void GcodeSuite::M575() {
+  const int32_t baud = parser.ulongval('B');
+  switch (baud) {
+    case 2400: case 9600: case 19200: case 38400: case 57600:
+    case 115200: case 250000: case 500000: case 1000000: {
+      const int8_t port = parser.intval('P', -99);
+      const bool set0 = (port == -99 || port == 0);
+      if (set0) {
+        SERIAL_ECHO_START();
+        SERIAL_ECHOLNPAIR(" Serial "
+          #if NUM_SERIAL > 1
+            , '0',
+          #else
+            "0"
+          #endif
+          " baud rate set to ", baud
+        );
+      }
+      #if NUM_SERIAL > 1
+        const bool set1 = (port == -99 || port == 1);
+        if (set1) {
+          SERIAL_ECHO_START();
+          SERIAL_ECHOLNPAIR(" Serial ", '1', " baud rate set to ", baud);
+        }
+      #endif
+
+      SERIAL_FLUSH();
+
+      if (set0) { MYSERIAL0.end(); MYSERIAL0.begin(baud); }
+
+      #if NUM_SERIAL > 1
+        if (set1) { MYSERIAL1.end(); MYSERIAL1.begin(baud); }
+      #endif
+
+    } break;
+    default: SERIAL_ECHO_MSG("?(B)aud rate is implausible.");
+  }
+}
+
+#endif // NUM_SERIAL > 0 && BAUD_RATE_GCODE

Marlin/src/gcode/gcode.cpp

@@ -669,6 +669,10 @@ void GcodeSuite::process_parsed_command(const bool no_ok/*=false*/) {
         case 540: M540(); break;                                  // M540: Set abort on endstop hit for SD printing
       #endif
 
+      #if ENABLED(BAUD_RATE_GCODE)
+        case 575: M575(); break;                                  // M575: Set serial baudrate
+      #endif
+
       #if HAS_BED_PROBE
         case 851: M851(); break;                                  // M851: Set Z Probe Z Offset
       #endif

Marlin/src/gcode/gcode.h

@@ -782,6 +782,10 @@ private:
     static void M540();
   #endif
 
+  #if ENABLED(BAUD_RATE_GCODE)
+    static void M575();
+  #endif
+
   #if ENABLED(ADVANCED_PAUSE_FEATURE)
     static void M600();
     static void M603();

Marlin/src/inc/Conditionals_post.h

@@ -1745,3 +1745,7 @@
     #define INIT_SDCARD_ON_BOOT
   #endif
 #endif
+
+#if !NUM_SERIAL
+  #undef BAUD_RATE_GCODE
+#endif