Zonestar P802M bed thermistor (#18289)

Co-authored-by: Scott Lahteine <github@thinkyhead.com>

Marlin/src/lcd/thermistornames.h

@@ -60,6 +60,8 @@
   #define THERMISTOR_NAME "ATC 104GT-2"
 #elif THERMISTOR_ID == 501
   #define THERMISTOR_NAME "Zonestar (Tronxy X3A)"
+#elif THERMISTOR_ID == 502
+  #define THERMISTOR_NAME "Zonestar (P802M Hot Bed)"
 #elif THERMISTOR_ID == 512
   #define THERMISTOR_NAME "RPW-Ultra"
 #elif THERMISTOR_ID == 6

Marlin/src/module/thermistor/thermistor_502.h

@@ -0,0 +1,60 @@
+/**
+ * Marlin 3D Printer Firmware
+ * Copyright (c) 2020 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/>.
+ *
+ */
+#pragma once
+
+// Unknown thermistor for the Zonestar P802M hot bed. Adjusted By Nerseth
+// These were the shipped settings from Zonestar in original firmware: P802M_8_Repetier_V1.6_Zonestar.zip
+const short temptable_502[][2] PROGMEM = {
+   { OV(  56.0 / 4), 300 },
+   { OV( 187.0 / 4), 250 },
+   { OV( 615.0 / 4), 190 },
+   { OV( 690.0 / 4), 185 },
+   { OV( 750.0 / 4), 180 },
+   { OV( 830.0 / 4), 175 },
+   { OV( 920.0 / 4), 170 },
+   { OV(1010.0 / 4), 165 },
+   { OV(1118.0 / 4), 160 },
+   { OV(1215.0 / 4), 155 },
+   { OV(1330.0 / 4), 145 },
+   { OV(1460.0 / 4), 140 },
+   { OV(1594.0 / 4), 135 },
+   { OV(1752.0 / 4), 130 },
+   { OV(1900.0 / 4), 125 },
+   { OV(2040.0 / 4), 120 },
+   { OV(2200.0 / 4), 115 },
+   { OV(2350.0 / 4), 110 },
+   { OV(2516.0 / 4), 105 },
+   { OV(2671.0 / 4),  98 },
+   { OV(2831.0 / 4),  92 },
+   { OV(2975.0 / 4),  85 },
+   { OV(3115.0 / 4),  76 },
+   { OV(3251.0 / 4),  72 },
+   { OV(3480.0 / 4),  62 },
+   { OV(3580.0 / 4),  52 },
+   { OV(3660.0 / 4),  46 },
+   { OV(3740.0 / 4),  40 },
+   { OV(3869.0 / 4),  30 },
+   { OV(3912.0 / 4),  25 },
+   { OV(3948.0 / 4),  20 },
+   { OV(4077.0 / 4), -20 },
+   { OV(4094.0 / 4), -55 }
+};

Marlin/src/module/thermistor/thermistors.h

@@ -70,6 +70,9 @@
 #if ANY_THERMISTOR_IS(501) // 100K Zonestar thermistor
   #include "thermistor_501.h"
 #endif
+#if ANY_THERMISTOR_IS(502) // Unknown thermistor used by the Zonestar Prusa P802M hot bed
+  #include "thermistor_502.h"
+#endif
 #if ANY_THERMISTOR_IS(512) // 100k thermistor in RPW-Ultra hotend, Pull-up = 4.7 kOhm, "unknown model"
   #include "thermistor_512.h"
 #endif

Marlin/src/pins/pins.h

@@ -291,7 +291,7 @@
 #elif MB(MELZI_MAKR3D)
   #include "sanguino/pins_MELZI_MAKR3D.h"       // ATmega644P, ATmega1284P                env:sanguino644p env:sanguino1284p
 #elif MB(MELZI_CREALITY)
-  #include "sanguino/pins_MELZI_CREALITY.h"     // ATmega1284P                            env:melzi env:melzi_optiboot
+  #include "sanguino/pins_MELZI_CREALITY.h"     // ATmega1284P                            env:melzi env:melzi_optimized env:melzi_optiboot
 #elif MB(MELZI_MALYAN)
   #include "sanguino/pins_MELZI_MALYAN.h"       // ATmega644P, ATmega1284P                env:sanguino644p env:sanguino1284p
 #elif MB(MELZI_TRONXY)

platformio.ini

@@ -166,6 +166,16 @@ platform      = atmelavr
 extends       = env:melzi
 upload_speed  = 115200
 
+#
+# Melzi and clones (Zonestar Melzi2 with tuned flags)
+#
+[env:melzi_optimized]
+platform      = atmelavr
+extends       = env:melzi
+upload_speed  = 115200
+build_flags   = ${common.build_flags} -fno-tree-scev-cprop -fno-split-wide-types -Wl,--relax -mcall-prologues
+build_unflags = -g -ggdb
+
 #
 # AT90USB1286 boards using CDC bootloader
 # - BRAINWAVE