Encoder: Add debounce

firmware/src/encoder.cpp

@@ -51,6 +51,8 @@ SwitchEvent handleSwitch() {
   return isPressed ? SWITCH_PRESSED : SWITCH_RELEASED;
 }
 
+unsigned long lastEncoderChangeAt = 0;
+
 EncoderEvent handleEncoder() {
   bool clk = digitalRead(CLK_PIN);
   bool dt = digitalRead(DT_PIN);
@@ -60,7 +62,11 @@ EncoderEvent handleEncoder() {
     return ENCODER_NONE;
   }
 
-  // TODO: Do we need to debounce encoder?
+  // debounce
+  auto now = millis();
+  if (now - lastEncoderChangeAt < DEBOUNCE_MS) {
+    return SWITCH_NONE;
+  }
 
   // clockwise pattern:
   // clk: 1001 1001
@@ -76,6 +82,7 @@ EncoderEvent handleEncoder() {
   // save state
   previousClk = clk;
   previousDt = dt;
+  lastEncoderChangeAt = now;
 
   // return event
   return event;