Create SimpleAtariExample

Tutorial/SimpleAtariExample

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+/*
+ * Simple Atari joystick adapter for learning purposes
+ * McGurk 6.9.2016
+ */
+
+#include "Joystick2.h"
+
+// Here we define pins we used. Along with these we have to connect joystick ground to Arduino GND.
+// Because of Arduino internal pullup resistor off state is 1. Moving joystick switches that to ground and then it is 0.
+#define UP 2
+#define DOWN 3
+#define LEFT 4
+#define RIGHT 5
+#define BUTTON 6
+
+
+// We keep record how everything was last time, so we can compare if anything have changed.
+byte lastUP = 1;
+byte lastDOWN = 1;
+byte lastLEFT = 1;
+byte lastRIGHT = 1;
+byte lastBUTTON = 1;
+
+byte newUP = 1;
+byte newDOWN = 1;
+byte newLEFT = 1;
+byte newRIGHT = 1;
+byte newBUTTON = 1;
+
+
+void setup() {
+  
+  pinMode(UP, INPUT_PULLUP);
+  pinMode(DOWN, INPUT_PULLUP);
+  pinMode(LEFT, INPUT_PULLUP);
+  pinMode(RIGHT, INPUT_PULLUP);
+  pinMode(BUTTON, INPUT_PULLUP);
+
+  Joystick[0].begin(false);
+  
+}
+
+// We use this flag to indicate if anything changes.
+byte flag = 0;
+
+
+void loop()
+{
+
+  // Read joystick state (1 = off, 0 = on).
+  newUP = digitalRead(UP);
+  newDOWN = digitalRead(DOWN);
+  newLEFT = digitalRead(LEFT);
+  newRIGHT = digitalRead(RIGHT);
+  newBUTTON = digitalRead(BUTTON);
+
+
+  // Check if anything changed. This way we don't have to send anything to USB, if nothing changes.
+  
+  if (newUP != lastUP) {
+    lastUP = newUP;
+    flag = 1;
+  }
+
+  if (newDOWN != lastDOWN) {
+    lastDOWN = newDOWN;
+    flag = 1;
+  }
+
+  if (newLEFT != lastLEFT) {
+    lastLEFT = newLEFT;
+    flag = 1;
+  }
+
+  if (newRIGHT != lastRIGHT) {
+    lastRIGHT = newRIGHT;
+    flag = 1;
+  }
+
+  if (newBUTTON != lastBUTTON) {
+    lastBUTTON = newBUTTON;
+    flag = 1;
+  }
+
+  // If anythings changed, send new state.
+  if (flag) {
+    
+    // Clear directions and buttons before start building new state.
+    Joystick[0].setYAxis(0);
+    Joystick[0].setXAxis(0);
+    Joystick[0].setButton(0, 0);
+    
+    // Build new state according what we read earlier.
+    // We need exclamation mark in these if-conditions, because swithes are active low (0 = on, 1 = off).
+    if (!newUP) {
+      Joystick[0].setYAxis(-127); //UP
+    }
+    if (!newDOWN) {
+      Joystick[0].setYAxis(127); //DOWN
+    }
+    if (!newLEFT) {
+      Joystick[0].setXAxis(-127); //LEFT
+    }
+    if (!newRIGHT) {
+      Joystick[0].setXAxis(127); //RIGHT
+    }
+    if (!newBUTTON) {
+      Joystick[0].setButton(0, 1); //BUTTON
+    }
+    
+    // Everything is ready. Send state. Before this point, we haven't send any joystick directions to USB.
+    Joystick[0].sendState();
+    
+    // Remember to clear flag.
+    flag = 0;
+    
+  }
+  
+  // Little 1ms breathing break.
+  delayMicroseconds(1000);
+  
+}