Godot + Arduino series: companion project code

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.
2026-08-09 21:14:55 +00:00
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+/*
+ * LedBasics.ino  —  Part 1: the minimal round trip.
+ *
+ * Godot sends "L1" / "L0" over USB serial (via the Python bridge) and this
+ * sketch toggles an LED. No sensors yet — Part 2 (JoystickBridge.ino) adds the
+ * joystick telemetry going the other way.
+ *
+ * PROTOCOL
+ *   IN (host -> Uno):  "L1" = LED on, "L0" = LED off  (newline-terminated)
+ *
+ * WIRING
+ *   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 before you've wired anything.)
+ */
+
+const uint8_t PIN_LED = 13;   // LED via 220 ohm resistor (also the onboard LED)
+
+char cmdBuf[8];
+uint8_t cmdLen = 0;
+
+void setup() {
+  Serial.begin(115200);
+  pinMode(PIN_LED, OUTPUT);
+  digitalWrite(PIN_LED, LOW);
+}
+
+void loop() {
+  // Commands in from Godot: "L1" / "L0", one per line.
+  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
+    }
+  }
+}