Reorganization of library structure to better match Arduino spec (#20)

Note, this will also require to you "uninstall and reinstall" the Arduino library due to the library file location changes.

Reviewed-on: https://git.pinkduck.xyz/awonak/libGravity/pulls/20

src/digital_output.h

@@ -0,0 +1,94 @@
+/**
+ * @file digital_output.h
+ * @author Adam Wonak (https://github.com/awonak)
+ * @brief Class for interacting with trigger / gate outputs.
+ * @version 0.1
+ * @date 2025-04-17
+ * 
+ * @copyright MIT - (c) 2025 - Adam Wonak - adam.wonak@gmail.com
+ *
+ */
+#ifndef DIGITAL_OUTPUT_H
+#define DIGITAL_OUTPUT_H
+
+#include <Arduino.h>
+
+const byte DEFAULT_TRIGGER_DURATION_MS = 5;
+
+class DigitalOutput {
+   public:
+    /**
+     * Initializes an CV Output paired object.
+     *
+     * @param cv_pin gpio pin for the cv output
+     */
+    void Init(uint8_t cv_pin) {
+        pinMode(cv_pin, OUTPUT);  // Gate/Trigger Output
+        cv_pin_ = cv_pin;
+        trigger_duration_ = DEFAULT_TRIGGER_DURATION_MS;
+    }
+
+    /**
+     * Set the trigger duration in miliseconds.
+     *
+     * @param duration_ms trigger duration in miliseconds
+     */
+    void SetTriggerDuration(uint8_t duration_ms) {
+        trigger_duration_ = duration_ms;
+    }
+
+    /**
+     * Turn the CV and LED on or off according to the input state.
+     *
+     * @param state Arduino digital HIGH or LOW values.
+     */
+    inline void Update(uint8_t state) {
+        if (state == HIGH) High();  // Rising
+        if (state == LOW) Low();    // Falling
+    }
+
+    // Sets the cv output HIGH to about 5v.
+    inline void High() { update(HIGH); }
+
+    // Sets the cv output LOW to 0v.
+    inline void Low() { update(LOW); }
+
+    /**
+     * Begin a Trigger period for this output.
+     */
+    inline void Trigger() {
+        update(HIGH);
+        last_triggered_ = millis();
+    }
+
+    /**
+     * Return a bool representing the on/off state of the output.
+     */
+    inline void Process() {
+        // If trigger is HIGH and the trigger duration time has elapsed, set the output low.
+        if (on_ && (millis() - last_triggered_) >= trigger_duration_) {
+            update(LOW);
+        }
+    }
+
+    /**
+     * Return a bool representing the on/off state of the output.
+     *
+     * @return true if current cv state is high, false if current cv state is low
+     */
+    inline bool On() { return on_; }
+
+   private:
+    unsigned long last_triggered_;
+    uint8_t trigger_duration_;
+    uint8_t cv_pin_;
+    uint8_t led_pin_;
+    bool on_;
+
+    void update(uint8_t state) {
+        digitalWrite(cv_pin_, state);
+        on_ = state == HIGH;
+    }
+};
+
+#endif