Arduino Sketch for future reference

Unreal/ArduinoButtonSketch/spie_arduino_ptt_sketch/spie_arduino_ptt_sketch/spie_arduino_ptt_sketch.ino

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+/*
+ * LED + Button Controller with Serial Commands and Smooth Pulsing
+ * ================================================================
+ *
+ * HARDWARE WIRING NOTES:
+ * ----------------------
+ * The switch (TRU Components LAS1-AGQ-11E/R/G) has an integrated LED rated
+ * for +12V with a built-in resistor. Since the Arduino cannot:
+ *   a) Supply 12V (it outputs 5V max)
+ *   b) Drive enough current for the LED directly
+ *   c) Do PWM dimming at 12V
+ *
+ * ...you MUST use an NPN Darlington transistor (TIP122) as a low-side switch.
+ *
+ * WIRING:
+ *   +12V PSU (+) --> LED+ on switch
+ *   LED- on switch --> COLLECTOR (TIP122 middle pin)
+ *   Arduino Pin 10 --> 1k Ohm resistor --> BASE (TIP122 left pin)
+ *   EMITTER (TIP122 right pin) --> GND
+ *   Arduino GND + 12V PSU GND --> tied together (common ground)
+ *
+ * SWITCH (button) WIRING:
+ *   COM --> Arduino Pin 9
+ *   NO  --> GND
+ *   NC  --> leave unconnected
+ *
+ * Pin 10 must be PWM-capable (Uno/Nano/Mega all support this).
+ *
+ * SERIAL COMMANDS:
+ *   LED_ON            -> Turn LED fully on (100%, stops pulsing)
+ *   LED_OFF           -> Turn LED fully off (stops pulsing)
+ *   LED_DIM:xx        -> Turn LED on at xx percent (0-100), e.g. LED_DIM:50
+ *   LED_PULSE_ON      -> Start smooth breathing/pulse animation
+ *   LED_PULSE_OFF     -> Stop pulsing (LED goes off)
+ *   CLEAR             -> Turn LED off (legacy command)
+ *
+ * BUTTON OUTPUT:
+ *   "B/true"  when pressed  (LOW with pull-up)
+ *   "B/false" when released (HIGH)
+ */
+
+// Constants for pin assignments
+const int ledPin = 10;        // Must be PWM-capable!
+const int buttonPin = 9;
+
+// Button state variables
+int buttonState = 1;
+int lastButtonState = 1;
+
+// Debounce timing
+unsigned long lastDebounceTime = 0;
+unsigned long debounceDelay = 50;
+
+// LED state machine
+enum LedMode {
+  LED_MODE_OFF,
+  LED_MODE_ON,
+  LED_MODE_DIM,
+  LED_MODE_PULSE
+};
+
+LedMode ledMode = LED_MODE_OFF;
+
+// Pulse animation variables
+unsigned long pulseStartTime = 0;
+const unsigned long pulseCycleMs = 3000;  // Full breath cycle duration in ms
+
+void setup() {
+  buttonState = 1;
+  pinMode(ledPin, OUTPUT);
+  pinMode(buttonPin, INPUT_PULLUP);
+  analogWrite(ledPin, 0);
+
+  Serial.begin(9600);
+}
+
+void loop() {
+  // --- Button debouncing ---
+  int reading = digitalRead(buttonPin);
+
+  if (reading != lastButtonState) {
+    lastDebounceTime = millis();
+  }
+
+  if ((millis() - lastDebounceTime) > debounceDelay) {
+    if (reading != buttonState) {
+      buttonState = reading;
+      if (buttonState == 0) {
+        Serial.println("B/true");
+      } else {
+        Serial.println("B/false");
+      }
+    }
+  }
+
+  lastButtonState = reading;
+
+  // --- Serial command handling ---
+  if (Serial.available() > 0) {
+    String command = Serial.readStringUntil('\n');
+    command.trim();
+
+    if (command == "LED_ON") {
+      ledMode = LED_MODE_ON;
+      analogWrite(ledPin, 255);
+    }
+    else if (command == "LED_OFF") {
+      ledMode = LED_MODE_OFF;
+      analogWrite(ledPin, 0);
+    }
+    else if (command.startsWith("LED_DIM:")) {
+      int percent = command.substring(8).toInt();
+      percent = constrain(percent, 0, 100);
+      int pwmValue = map(percent, 0, 100, 0, 255);
+      ledMode = LED_MODE_DIM;
+      analogWrite(ledPin, pwmValue);
+    }
+    else if (command == "LED_PULSE_ON") {
+      ledMode = LED_MODE_PULSE;
+      pulseStartTime = millis();
+    }
+    else if (command == "LED_PULSE_OFF") {
+      ledMode = LED_MODE_OFF;
+      analogWrite(ledPin, 0);
+    }
+    else if (command.startsWith("CLEAR")) {
+      ledMode = LED_MODE_OFF;
+      analogWrite(ledPin, 0);
+    }
+  }
+
+  // --- Pulse animation (non-blocking) ---
+  if (ledMode == LED_MODE_PULSE) {
+    unsigned long elapsed = millis() - pulseStartTime;
+    unsigned long pos = elapsed % pulseCycleMs;
+
+    // Sine wave: 0 -> 1 -> 0 over one full "breath" cycle
+    float phase = (float)pos / (float)pulseCycleMs;
+    float brightness = sin(phase * PI);
+    brightness = brightness * brightness;               // Squared for organic ease-in-out
+
+    // Min ~8 so LED never fully goes dark (subtle "alive" glow at trough)
+    int pwmValue = 2 + (int)(brightness * 247.0);
+    analogWrite(ledPin, pwmValue);
+  }
+}