Started adding the rotary encoder

If only soldering could be a commit...

src/main.cpp

@@ -38,6 +38,7 @@
 #include <Arduino.h>
 #include "595n.h"
 #include "165.h"
+#include "rotaryEncoder.h"
 #include <Joystick.h>
 
 // NOTES - 595N
@@ -145,6 +146,8 @@ Joystick_ Joystick(
   false
 );
 
+RotaryEncoder re1 = NewRotaryEncoder(14, 16);
+
 #define PULSE_DURATION 100 // ms
 
 const int pulseButtons[] = {
@@ -173,10 +176,12 @@ void setup() {
   }
 
   SR595N_write(&input, 0b00000100);
+  RotaryEncoder_init(&re1);
 }
 
 // TODO - comment this debugging thing at the end
 // unsigned long lastPrint = 0;
+int lastRE = 0;
 void loop(void) {
   unsigned long currentMillis = millis();
 

src/rotaryEncoder.cpp

@@ -0,0 +1,32 @@
+#include "rotaryEncoder.h"
+#include "Arduino.h"
+
+RotaryEncoder NewRotaryEncoder(int clk, int dt) {
+  return RotaryEncoder{
+    .clkPin = clk,
+    .dtPin = dt,
+  };
+}
+
+void RotaryEncoder_init(RotaryEncoder *enc) {
+  pinMode(enc->clkPin, INPUT_PULLUP);
+  pinMode(enc->dtPin, INPUT_PULLUP);
+  enc->lastStateCLK = digitalRead(enc->clkPin);
+}
+
+int RotaryEncoder_read(RotaryEncoder *enc) {
+  int curStateClk = digitalRead(enc->clkPin);
+  int direction = RE_NOCHANGE;
+  
+  if (curStateClk != enc->lastStateCLK && curStateClk == 1) {
+    if (digitalRead(enc->dtPin) != curStateClk) {
+      direction = RE_CCW; 
+    } else {
+      direction = RE_CW; 
+    }
+  }
+
+  enc->lastStateCLK = curStateClk;
+
+  return direction;
+}

src/rotaryEncoder.h

@@ -0,0 +1,19 @@
+#ifndef __ROTARY_ENC__
+#define __ROTARY_ENC__
+
+const int RE_NOCHANGE = 0;
+const int RE_CCW = -1;
+const int RE_CW = 1;
+
+typedef struct {
+  int clkPin;
+  int dtPin;
+
+  int lastStateCLK;
+} RotaryEncoder;
+
+RotaryEncoder NewRotaryEncoder(int clk, int dt);
+void RotaryEncoder_init(RotaryEncoder *enc);
+int RotaryEncoder_read(RotaryEncoder *enc);
+
+#endif