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Godot + Arduino series: companion project code

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Self-contained project code for the "Godot Isn't Just for Games" series:
Arduino sketches, the Python serial<->UDP bridge, and the Godot 4 projects,
one folder per article.
This commit is contained in:
tyler parker
2026-08-09 21:14:55 +00:00
commit bb1d70c620
21 changed files with 1010 additions and 0 deletions
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godot-arduino-2-joystick-dashboard/README.md
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# Part 2 — A Live Joystick Dashboard
Code for *"Godot Isn't Just for Games: A Live Joystick Dashboard"* **(article coming soon).**
Builds on [Part 1](../godot-arduino-1-led-first-light): a 2-axis KY-023 joystick streams
its position up the same bridge into a Godot console — a glowing dot tracks the
stick across an XY pad in real time, with the LED button still working.
## Contents
```
arduino/
JoystickBridge/JoystickBridge.ino # streams "x,y,btn" + still drives the LED
bridge/bridge.py # same serial <-> UDP relay as Part 1
godot/
ArduinoGodot/ # Godot 4 project: XY pad + dot + LED button
```
## Wiring (adds to Part 1)
KY-023 joystick: `+5V`→5V, `GND`→GND, `VRx`→A0, `VRy`→A1, `SW`→D2. Keep the
LED from Part 1 on D13.
## Run it
1. **Flash** `arduino/JoystickBridge/JoystickBridge.ino` to the Uno.
2. **Bridge:** `python arduino/bridge/bridge.py` (leave running).
3. **Godot:** open `godot/ArduinoGodot/` in Godot 4 and press Play — move the stick.
godot-arduino-2-joystick-dashboard/arduino/JoystickBridge/JoystickBridge.ino
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/*
* JoystickBridge.ino — Arduino Uno <-> Godot (ArduinoGodot/Main.gd)
*
* Talks plain serial lines to the UDP<->serial bridge process, which forwards
* telemetry to Godot on UDP 4242 and relays LED commands from UDP 4243.
*
* PROTOCOL (must match Main.gd)
* OUT (Uno -> host): "x,y,btn\n" raw 10-bit ADC, e.g. "512,498,1"
* btn = 1 when the stick's push-button is pressed.
* IN (host -> Uno): "L1" = LED on, "L0" = LED off (newline optional)
*
* WIRING (KY-023 2-axis analog joystick + external LED)
* Joystick +5V / VCC -> 5V
* Joystick GND -> GND
* Joystick VRx -> A0
* Joystick VRy -> A1
* Joystick SW -> D2 (uses internal pull-up; pressed = LOW)
*
* LED: D13 -> 220 ohm resistor -> LED anode (+, long leg)
* LED cathode (-, short leg) -> GND
* (D13 is also the Uno's onboard LED, so it flashes during every upload —
* a free "is this pin alive" check. 220-330 ohm keeps it near ~15 mA.)
*/
const uint8_t PIN_VRX = A0; // joystick X axis
const uint8_t PIN_VRY = A1; // joystick Y axis
const uint8_t PIN_SW = 2; // joystick push-button (active LOW)
const uint8_t PIN_LED = 13; // external LED through a 220 ohm resistor (also onboard LED)
const unsigned long BAUD = 115200; // must match the bridge process
const unsigned long SEND_MS = 16; // ~60 Hz telemetry
unsigned long lastSend = 0;
char cmdBuf[8];
uint8_t cmdLen = 0;
void setup() {
Serial.begin(BAUD);
pinMode(PIN_SW, INPUT_PULLUP);
pinMode(PIN_LED, OUTPUT);
digitalWrite(PIN_LED, LOW);
}
void loop() {
handleCommands();
unsigned long now = millis();
if (now - lastSend >= SEND_MS) {
lastSend = now;
int x = analogRead(PIN_VRX); // 0..1023
int y = analogRead(PIN_VRY); // 0..1023
int btn = (digitalRead(PIN_SW) == LOW) // pull-up: LOW == pressed
? 1 : 0; // Godot wants 1 = pressed
// "x,y,btn\n"
Serial.print(x);
Serial.print(',');
Serial.print(y);
Serial.print(',');
Serial.println(btn);
}
}
// Parse newline-terminated commands. Recognizes "L1" / "L0".
void handleCommands() {
while (Serial.available() > 0) {
char c = Serial.read();
if (c == '\n' || c == '\r') {
if (cmdLen >= 2 && cmdBuf[0] == 'L') {
digitalWrite(PIN_LED, cmdBuf[1] == '1' ? HIGH : LOW);
}
cmdLen = 0;
} else if (cmdLen < sizeof(cmdBuf) - 1) {
cmdBuf[cmdLen++] = c;
} else {
cmdLen = 0; // overflow guard: drop the runt line
}
}
}
godot-arduino-2-joystick-dashboard/arduino/bridge/bridge.py
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#!/usr/bin/env python3
"""
bridge.py — serial <-> UDP relay between the Arduino Uno and Godot (Main.gd)
Godot never touches the serial port; it only speaks UDP:
* it LISTENS on 127.0.0.1:4242 for telemetry ("x,y,btn")
* it SENDS to 127.0.0.1:4243 for LED commands ("L1" / "L0")
This bridge sits in the middle:
Arduino --serial line "x,y,btn\\n"--> bridge --UDP--> Godot :4242
Godot :4243 --UDP "L1"/"L0"--> bridge --serial--> Arduino
Double-click friendly: with no arguments it auto-detects the Arduino port and
keeps the window open on exit so you can read any error. Override if needed:
python bridge.py --port COM3
python bridge.py --port COM3 --baud 115200 # baud must match the .ino
Requires pyserial: pip install pyserial
"""
import argparse
import socket
import sys
import time
try:
import serial # pyserial
from serial.tools import list_ports
except ImportError:
print("pyserial not installed. Run: pip install pyserial")
input("\nPress Enter to close...")
sys.exit(1)
TELEMETRY_ADDR = ("127.0.0.1", 4242) # Godot listens here
COMMAND_PORT = 4243 # Godot sends LED commands here
# Substrings that identify a typical Uno / clone in the port description.
PORT_HINTS = ("arduino", "ch340", "usb-serial", "usb serial", "wchusb", "cp210")
def pick_port() -> str:
"""Return a serial port: the obvious Arduino one, else the only one, else ask."""
ports = list(list_ports.comports())
if not ports:
raise SystemExit("No serial ports found. Is the Uno plugged in?")
for p in ports:
blob = f"{p.description} {p.manufacturer or ''}".lower()
if any(h in blob for h in PORT_HINTS):
print(f"auto-detected {p.device} ({p.description})")
return p.device
if len(ports) == 1:
print(f"using only port {ports[0].device} ({ports[0].description})")
return ports[0].device
print("Multiple serial ports found:")
for i, p in enumerate(ports):
print(f" [{i}] {p.device} {p.description}")
choice = input("Pick a number: ").strip()
return ports[int(choice)].device
def run(port: str, baud: int) -> None:
# UDP socket: sends telemetry to Godot AND receives LED commands from it.
# Bind to all interfaces ("") not just 127.0.0.1 — on some Windows setups a
# loopback-only bind won't see packets whose source the sender picked freely.
udp = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
udp.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
udp.bind(("", COMMAND_PORT))
udp.setblocking(False)
# Open the serial port. A short timeout keeps readline() from blocking forever.
ser = serial.Serial(port, baud, timeout=0.05)
time.sleep(2.0) # Uno auto-resets when the port opens; wait for the sketch to boot
ser.reset_input_buffer()
print(f"bridge up: {port}@{baud} -> UDP {TELEMETRY_ADDR}, <- UDP :{COMMAND_PORT}")
print("leave this window open. Ctrl+C to quit.")
try:
while True:
# 1) Arduino -> Godot: forward each complete telemetry line.
line = ser.readline() # b"x,y,btn\r\n" or b"" on timeout
if line:
text = line.strip()
if text:
udp.sendto(text, TELEMETRY_ADDR)
# 2) Godot -> Arduino: drain any pending LED commands, newest applied last.
while True:
try:
data, src = udp.recvfrom(64)
except BlockingIOError:
break
except ConnectionResetError:
# Windows: a prior sendto hit a closed port; ICMP resets recv. Ignore.
break
cmd = data.strip()
if cmd in (b"L1", b"L0"):
ser.write(cmd + b"\n")
ser.flush()
print(f"cmd {cmd.decode()} from {src} -> serial")
else:
print(f"ignored UDP {data!r} from {src}")
except KeyboardInterrupt:
pass
finally:
ser.close()
udp.close()
print("\nbridge closed.")
def main() -> None:
ap = argparse.ArgumentParser(description="Arduino <-> Godot serial/UDP bridge")
ap.add_argument("--port", help="serial port, e.g. COM3 (auto-detected if omitted)")
ap.add_argument("--baud", type=int, default=115200, help="must match JoystickBridge.ino")
args = ap.parse_args()
try:
port = args.port or pick_port()
run(port, args.baud)
except Exception as e:
# Keep the window open so double-click users can actually read the error.
print(f"\nERROR: {e}")
input("\nPress Enter to close...")
if __name__ == "__main__":
main()
godot-arduino-2-joystick-dashboard/godot/ArduinoGodot/LedBasics.gd
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extends Control
# Part 1 — the minimal round trip: a Godot button that toggles an LED on the
# Arduino. Only the OUTBOUND (command) half of the link is used here; Part 2
# adds inbound telemetry from the joystick.
const COMMAND_ADDR := "127.0.0.1"
const COMMAND_PORT := 4243
@onready var led_button: Button = $Panel/LedButton
var _udp_out := PacketPeerUDP.new()
var _led_on := false
func _ready() -> void:
# To SEND with PacketPeerUDP in Godot 4, use set_dest_address — NOT
# connect_to_host, which is for receiving and silently drops outbound packets.
_udp_out.set_dest_address(COMMAND_ADDR, COMMAND_PORT)
led_button.pressed.connect(_on_led_pressed)
func _on_led_pressed() -> void:
_led_on = not _led_on
_udp_out.put_packet(("L1" if _led_on else "L0").to_utf8_buffer())
led_button.text = "LED: ON" if _led_on else "LED: OFF"
godot-arduino-2-joystick-dashboard/godot/ArduinoGodot/LedBasics.gd.uid
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uid://ctgyyk0it7dpd
godot-arduino-2-joystick-dashboard/godot/ArduinoGodot/LedBasics.tscn
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[gd_scene load_steps=6 format=3]
[ext_resource type="Script" path="res://LedBasics.gd" id="1_led"]
[sub_resource type="StyleBoxFlat" id="bg"]
bg_color = Color(0.043, 0.055, 0.078, 1)
[sub_resource type="StyleBoxFlat" id="btn_normal"]
bg_color = Color(0.11, 0.145, 0.204, 1)
border_width_left = 1
border_width_top = 1
border_width_right = 1
border_width_bottom = 1
border_color = Color(0.2, 0.6, 1, 0.5)
corner_radius_top_left = 8
corner_radius_top_right = 8
corner_radius_bottom_right = 8
corner_radius_bottom_left = 8
[sub_resource type="StyleBoxFlat" id="btn_hover"]
bg_color = Color(0.145, 0.196, 0.278, 1)
border_width_left = 1
border_width_top = 1
border_width_right = 1
border_width_bottom = 1
border_color = Color(0.3, 0.7, 1, 1)
corner_radius_top_left = 8
corner_radius_top_right = 8
corner_radius_bottom_right = 8
corner_radius_bottom_left = 8
[sub_resource type="StyleBoxFlat" id="btn_pressed"]
bg_color = Color(0.2, 0.6, 1, 1)
corner_radius_top_left = 8
corner_radius_top_right = 8
corner_radius_bottom_right = 8
corner_radius_bottom_left = 8
[node name="Main" type="Control"]
layout_mode = 3
anchors_preset = 15
anchor_right = 1.0
anchor_bottom = 1.0
script = ExtResource("1_led")
[node name="Panel" type="Panel" parent="."]
layout_mode = 1
anchors_preset = 15
anchor_right = 1.0
anchor_bottom = 1.0
theme_override_styles/panel = SubResource("bg")
[node name="Title" type="Label" parent="Panel"]
layout_mode = 0
offset_left = 40.0
offset_top = 96.0
offset_right = 480.0
offset_bottom = 130.0
theme_override_colors/font_color = Color(0.85, 0.93, 1, 1)
theme_override_font_sizes/font_size = 24
text = "GODOT + ARDUINO: LED"
horizontal_alignment = 1
vertical_alignment = 1
[node name="Subtitle" type="Label" parent="Panel"]
layout_mode = 0
offset_left = 40.0
offset_top = 132.0
offset_right = 480.0
offset_bottom = 152.0
theme_override_colors/font_color = Color(0.4, 0.55, 0.7, 1)
theme_override_font_sizes/font_size = 12
text = "· click to reach down the wire ·"
horizontal_alignment = 1
vertical_alignment = 1
[node name="LedButton" type="Button" parent="Panel"]
layout_mode = 0
offset_left = 150.0
offset_top = 220.0
offset_right = 370.0
offset_bottom = 284.0
theme_override_colors/font_color = Color(0.85, 0.93, 1, 1)
theme_override_colors/font_hover_color = Color(1, 1, 1, 1)
theme_override_colors/font_pressed_color = Color(0.043, 0.055, 0.078, 1)
theme_override_font_sizes/font_size = 18
theme_override_styles/normal = SubResource("btn_normal")
theme_override_styles/hover = SubResource("btn_hover")
theme_override_styles/pressed = SubResource("btn_pressed")
theme_override_styles/focus = SubResource("btn_normal")
text = "LED: OFF"
godot-arduino-2-joystick-dashboard/godot/ArduinoGodot/Main.gd
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extends Control
const TELEMETRY_PORT := 4242
const COMMAND_ADDR := "127.0.0.1"
const COMMAND_PORT := 4243
const ADC_MAX := 1023.0
const SMOOTH_SPEED := 12.0 # higher = snappier, lower = floatier
@onready var led_button: Button = $Panel/LedButton
@onready var pad: Panel = $Panel/Pad
@onready var dot: ColorRect = $Panel/Pad/Dot
var _udp_in := PacketPeerUDP.new()
var _udp_out := PacketPeerUDP.new()
var _target_x := 512.0 # rest near center so the dot starts in the middle
var _target_y := 512.0
var _smoothed_x := 512.0
var _smoothed_y := 512.0
var _btn_pressed := false
var _led_on := false
const COLOR_DOT_IDLE := Color(0.3, 0.7, 1.0) # cyan
const COLOR_DOT_PRESSED := Color(0.2, 1.0, 0.4) # green
func _ready() -> void:
_udp_in.bind(TELEMETRY_PORT, "127.0.0.1")
# set_dest_address is the reliable way to *send* with PacketPeerUDP in Godot 4;
# connect_to_host is aimed at receiving and can silently drop outbound packets.
_udp_out.set_dest_address(COMMAND_ADDR, COMMAND_PORT)
led_button.pressed.connect(_on_led_pressed)
func _process(delta: float) -> void:
# Drain the queue; the newest packet wins. Format: "x,y,btn" e.g. "512,498,0"
while _udp_in.get_available_packet_count() > 0:
var parts := _udp_in.get_packet().get_string_from_utf8().split(",")
if parts.size() >= 3 and parts[0].is_valid_int() and parts[1].is_valid_int():
_target_x = float(parts[0])
_target_y = float(parts[1])
_btn_pressed = parts[2].strip_edges() == "1"
# Frame-rate-independent smoothing so the dot glides instead of twitching.
var t := 1.0 - exp(-SMOOTH_SPEED * delta)
_smoothed_x = lerpf(_smoothed_x, _target_x, t)
_smoothed_y = lerpf(_smoothed_y, _target_y, t)
# Normalize raw ADC (0..1023) to 0..1.
var nx := clampf(_smoothed_x / ADC_MAX, 0.0, 1.0)
var ny := clampf(_smoothed_y / ADC_MAX, 0.0, 1.0)
# Move the dot within the pad. Invert Y so pushing the stick UP moves the dot UP.
# (If it feels backwards, change "1.0 - ny" to "ny", or swap for X below.)
var travel := pad.size - dot.size
dot.position = Vector2(nx * travel.x, (1.0 - ny) * travel.y)
# Reflect the stick's push-button by recoloring the dot.
dot.color = COLOR_DOT_PRESSED if _btn_pressed else COLOR_DOT_IDLE
func _on_led_pressed() -> void:
_led_on = not _led_on
_udp_out.put_packet(("L1" if _led_on else "L0").to_utf8_buffer())
led_button.text = "LED: ON" if _led_on else "LED: OFF"
godot-arduino-2-joystick-dashboard/godot/ArduinoGodot/Main.gd.uid
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uid://d103i6ghi3ydl
godot-arduino-2-joystick-dashboard/godot/ArduinoGodot/Main.tscn
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[gd_scene format=3 uid="uid://b81ornfxnvxxo"]
[ext_resource type="Script" uid="uid://d103i6ghi3ydl" path="res://Main.gd" id="1_main"]
[sub_resource type="StyleBoxFlat" id="bg"]
bg_color = Color(0.043, 0.055, 0.078, 1)
[sub_resource type="StyleBoxFlat" id="pad"]
bg_color = Color(0.071, 0.09, 0.125, 1)
border_width_left = 1
border_width_top = 1
border_width_right = 1
border_width_bottom = 1
border_color = Color(0.2, 0.6, 1, 0.55)
corner_radius_top_left = 10
corner_radius_top_right = 10
corner_radius_bottom_right = 10
corner_radius_bottom_left = 10
shadow_color = Color(0.2, 0.6, 1, 0.15)
shadow_size = 12
[sub_resource type="StyleBoxFlat" id="btn_normal"]
bg_color = Color(0.11, 0.145, 0.204, 1)
border_width_left = 1
border_width_top = 1
border_width_right = 1
border_width_bottom = 1
border_color = Color(0.2, 0.6, 1, 0.5)
corner_radius_top_left = 8
corner_radius_top_right = 8
corner_radius_bottom_right = 8
corner_radius_bottom_left = 8
[sub_resource type="StyleBoxFlat" id="btn_pressed"]
bg_color = Color(0.2, 0.6, 1, 1)
corner_radius_top_left = 8
corner_radius_top_right = 8
corner_radius_bottom_right = 8
corner_radius_bottom_left = 8
[sub_resource type="StyleBoxFlat" id="btn_hover"]
bg_color = Color(0.145, 0.196, 0.278, 1)
border_width_left = 1
border_width_top = 1
border_width_right = 1
border_width_bottom = 1
border_color = Color(0.3, 0.7, 1, 1)
corner_radius_top_left = 8
corner_radius_top_right = 8
corner_radius_bottom_right = 8
corner_radius_bottom_left = 8
[node name="Main" type="Control" unique_id=2088197079]
layout_mode = 3
anchors_preset = 15
anchor_right = 1.0
anchor_bottom = 1.0
grow_horizontal = 2
grow_vertical = 2
script = ExtResource("1_main")
[node name="Panel" type="Panel" parent="." unique_id=2059422118]
layout_mode = 1
anchors_preset = 15
anchor_right = 1.0
anchor_bottom = 1.0
grow_horizontal = 2
grow_vertical = 2
theme_override_styles/panel = SubResource("bg")
[node name="Title" type="Label" parent="Panel" unique_id=1798584764]
layout_mode = 0
offset_left = 40.0
offset_top = 28.0
offset_right = 480.0
offset_bottom = 58.0
theme_override_colors/font_color = Color(0.85, 0.93, 1, 1)
theme_override_font_sizes/font_size = 22
text = "GODOT + ARDUINO DEMO"
horizontal_alignment = 1
vertical_alignment = 1
[node name="Subtitle" type="Label" parent="Panel" unique_id=462472763]
layout_mode = 0
offset_left = 40.0
offset_top = 60.0
offset_right = 480.0
offset_bottom = 78.0
theme_override_colors/font_color = Color(0.4, 0.55, 0.7, 1)
theme_override_font_sizes/font_size = 12
text = "· real-time serial link ·"
horizontal_alignment = 1
vertical_alignment = 1
[node name="Pad" type="Panel" parent="Panel" unique_id=1034082861]
layout_mode = 0
offset_left = 70.0
offset_top = 104.0
offset_right = 450.0
offset_bottom = 484.0
theme_override_styles/panel = SubResource("pad")
[node name="CrosshairV" type="ColorRect" parent="Panel/Pad" unique_id=1237114789]
layout_mode = 0
offset_left = 189.0
offset_right = 191.0
offset_bottom = 380.0
color = Color(0.2, 0.6, 1, 0.12)
[node name="CrosshairH" type="ColorRect" parent="Panel/Pad" unique_id=1265685762]
layout_mode = 0
offset_top = 189.0
offset_right = 380.0
offset_bottom = 191.0
color = Color(0.2, 0.6, 1, 0.12)
[node name="Dot" type="ColorRect" parent="Panel/Pad" unique_id=2003621157]
layout_mode = 0
offset_right = 28.0
offset_bottom = 28.0
color = Color(0.3, 0.7, 1, 1)
[node name="LedButton" type="Button" parent="Panel" unique_id=1325564653]
layout_mode = 0
offset_left = 160.0
offset_top = 516.0
offset_right = 360.0
offset_bottom = 566.0
theme_override_colors/font_color = Color(0.85, 0.93, 1, 1)
theme_override_colors/font_pressed_color = Color(0.043, 0.055, 0.078, 1)
theme_override_colors/font_hover_color = Color(1, 1, 1, 1)
theme_override_font_sizes/font_size = 18
theme_override_styles/normal = SubResource("btn_normal")
theme_override_styles/pressed = SubResource("btn_pressed")
theme_override_styles/hover = SubResource("btn_hover")
theme_override_styles/focus = SubResource("btn_normal")
text = "LED: OFF"
godot-arduino-2-joystick-dashboard/godot/ArduinoGodot/project.godot
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; Engine configuration file.
; It's best edited using the editor UI and not directly,
; since the parameters that go here are not all obvious.
;
; Format:
; [section] ; section goes between []
; param=value ; assign values to parameters
config_version=5
[application]
config/name="ArduinoGodot"
run/main_scene="res://Main.tscn"
config/features=PackedStringArray("4.7")
[display]
window/size/viewport_width=520
window/size/viewport_height=610
[dotnet]
project/assembly_name="ArduinoGodot"