config: Tarantula Pro - Multiple tweaks and description change (#3230)

The following parameters have been tweaked:
 - X endstop position has been set to -2, as per original marlin cofig
 - Second Z axis disabled by default (this must be purchased as an
   add-on)

The comment at the top of this file has also been modified to describe
the difference between this (old) model and the new (rebranded) Tevo
Tarantula pro.

Signed-off-by: Oliver Fawcett-Griffiths <olly@ollyfg.com>

config/printer-tevo-tarantula-pro-2020.cfg

@@ -1,5 +1,9 @@
-# Support for Tevo Tarantula Pro. To use this config, the firmware should be
-# compiled for the AVR atmega2560.
+# Support for the green Tevo Tarantula Pro. To use this config, the firmware
+# should be compiled for the AVR atmega2560.
+# Note that this config file is for the "old green" Tarantula pro, with a
+# MKS Gen_l 8-bit board.
+# It _will not_ work out of the box for the "new orange" Tarantula pro with a
+# MKS Sgen_l 32-bit board.
 
 # See the example.cfg file for a description of available parameters.
 
@@ -9,8 +13,9 @@ dir_pin: !ar55
 enable_pin: !ar38
 step_distance: 0.012583
 endstop_pin: ^!ar3
-position_endstop: 0
+position_endstop: -2
 position_max: 220
+position_min: -2
 homing_speed: 25.0
 
 [stepper_y]
@@ -21,7 +26,7 @@ step_distance: 0.01256
 endstop_pin: ^!ar14
 position_endstop: 0
 position_max: 220
-homing_speed: 25
+homing_speed: 25.0
 
 [stepper_z]
 step_pin: ar46
@@ -32,11 +37,12 @@ endstop_pin: ^!ar18
 position_endstop: 0
 position_max: 200
 
-[stepper_z1]
-step_pin: ar36
-dir_pin: ar34
-enable_pin: !ar30
-step_distance: 0.002492
+# Enable for dual-z addon
+#[stepper_z1]
+#step_pin: ar36
+#dir_pin: ar34
+#enable_pin: !ar30
+#step_distance: 0.002492
 
 [extruder]
 step_pin: ar26
@@ -75,15 +81,12 @@ pin_map: arduino
 kinematics: cartesian
 max_velocity: 400
 max_accel: 3000
-#max_accel_to_decel:
 max_z_velocity: 50
 max_z_accel: 100
-#square_corner_velocity: 5.0
 
 [heater_fan nozzle_fan]
 pin: ar7
 
-
 [display]
 lcd_type: uc1701
 cs_pin: ar25