config: Add example configuration for Creality Ender 3 V2 (#3144)

Includes special serial configuration and flashing instructions for the
Creality V4.2.2 board.

Signed-off-by: John Gross <jmgross@jmgross.dev>

config/printer-creality-ender-3-v2-2020.cfg

@@ -0,0 +1,88 @@
+# This file contains pin mappings for the stock 2020 Creality
+# Ender 3 V2. To use this config, the firmware should be compiled
+# for the STM32F103 with a 28KiB bootloader. To use the front USB
+# port for communication, select serial port USART1.
+
+# If you prefer a direct serial connection, USART3 is broken out
+# on the 10 pin IDC cable used for the LCD module as follows:
+# 3: Tx, 4: Rx, 9: GND, 10: VCC
+
+# Flash this firmware by copying "out/klipper.bin" to a SD card and
+# turning on the printer with the card inserted. The firmware
+# filename must end in ".bin" and must not match the last filename
+# that was flashed.
+
+# See the example.cfg file for a description of available parameters.
+
+[stepper_x]
+step_pin: PC2
+dir_pin: PB9
+enable_pin: !PC3
+step_distance: .0125
+endstop_pin: ^PA5
+position_endstop: 0
+position_max: 235
+homing_speed: 50
+
+[stepper_y]
+step_pin: PB8
+dir_pin: PB7
+enable_pin: !PC3
+step_distance: .0125
+endstop_pin: ^PA6
+position_endstop: 0
+position_max: 235
+homing_speed: 50
+
+[stepper_z]
+step_pin: PB6
+dir_pin: !PB5
+enable_pin: !PC3
+step_distance: .0025
+endstop_pin: ^PA7
+position_endstop: 0.0
+position_max: 250
+
+[extruder]
+max_extrude_only_distance: 100.0
+step_pin: PB4
+dir_pin: PB3
+enable_pin: !PC3
+step_distance: 0.010752
+nozzle_diameter: 0.400
+filament_diameter: 1.750
+heater_pin: PA1
+sensor_type: EPCOS 100K B57560G104F
+sensor_pin: PC5
+control: pid
+# tuned for stock hardware with 200 degree Celsius target
+pid_Kp: 21.527
+pid_Ki: 1.063
+pid_Kd: 108.982
+min_temp: 0
+max_temp: 250
+
+[heater_bed]
+heater_pin: PA2
+sensor_type: EPCOS 100K B57560G104F
+sensor_pin: PC4
+control: pid
+# tuned for stock hardware with 50 degree Celsius target
+pid_Kp: 54.027
+pid_Ki: 0.770
+pid_Kd: 948.182
+min_temp: 0
+max_temp: 130
+
+[fan]
+pin: PA0
+
+[mcu]
+serial: /dev/serial/by-id/usb-1a86_USB_Serial-if00-port0
+
+[printer]
+kinematics: cartesian
+max_velocity: 300
+max_accel: 3000
+max_z_velocity: 5
+max_z_accel: 100