Use Y axis as buttons

Makefile

@@ -3,7 +3,7 @@
 BOARD_TAG    = leonardo
 MONITOR_PORT = /dev/ttyACM0
 ARDUINO_DIR = /home/dan/projects/arduino-1.8.9
-ARDUINO_LIBS = HID Mouse Joystick
+ARDUINO_LIBS = HID Joystick
 CTAGS_EXEC = /usr/bin/ctags
 CTAGS_OPTS = -e
 ARDMK_DIR = /home/dan/projects/avr/Arduino-Makefile

README.org

@@ -7,11 +7,23 @@ trivial.
 
 * Compiling
 Install the dependencies:
+
 - [[https://github.com/sudar/Arduino-Makefile][Arduino Makefile]] (available as arduino-mk in Ubuntu/Debiab)
 - [[https://github.com/MHeironimus/ArduinoJoystickLibrary][Arduino Joystick Library]]
 
+Tweak ~joystick.ino~ to suit your needs. In particular, enable or
+disable using the Y axis as additional buttons.
+
 Then just run ~make~ and ~make upload~ to flash the board.
 
+** Y axis as buttons
+Using the Y axis on the joystick as additional buttons is useful for
+playing e.g. SuperTuxKart, where you only need the joystick for
+steering.
+
 * Wiring
 There is nothing to wire -- just pop the shield onto your board and
 plug it in!
+
+* Debugging
+You can use the ~jstest~ tool on Linux.

joystick.ino

@@ -1,8 +1,12 @@
 /* We use the Joystick library from:
    <https://github.com/MHeironimus/ArduinoJoystickLibrary> */
 #include <Joystick.h>
-#include <Mouse.h>
 #define DELAY 5
+/* Whether to use the Y axis as two buttons. This is useful for
+   playing SuperTuxKart. Set this to 2 if you want to enable this
+   feature and to 0 otherwise. */
+#define USE_Y_AS_BUTTONS 2
+
 
 const int sw_pin = 2;
 const int vrx_pin = A0;
@@ -18,34 +22,37 @@ const int base_y = 519;
 const int max_x = 1023;
 const int max_y = 1023;
 
-
-
+/* joystick info will be read from -rng to +rng */
 const int rng = 500;
+/* If USE_Y_AS_BUTTONS is set up: joystick data above this will count as a click */
+const int threshold = 50;
 
-
-int mouse_mode = 0;
 int prev_readings[btn_count];
 
 
 Joystick_ Joystick(JOYSTICK_DEFAULT_REPORT_ID,
                    JOYSTICK_TYPE_GAMEPAD,
-                   btn_count, // buttons
-                   1, // joystick hat switches
+                   btn_count + USE_Y_AS_BUTTONS, // buttons
+                   0, // joystick hat switches
                    true, // X axis
+#if USE_Y_AS_BUTTONS == 0
                    true, // Y axis
+#else
+                   false, // Y axis
+#endif
                    false,  // Z axis
                    false, false, false, false, false, false, false, false);
 
-void setup() {                
+void setup() {
   pinMode(sw_pin, INPUT);
   for (int i = 0; i < btn_count; i++) {
     pinMode(btn_pins[i], INPUT);
     prev_readings[i] = 0;
   }
-  Mouse.begin();
   Joystick.begin();
   Joystick.setXAxisRange(-rng, rng);
-  Joystick.setYAxisRange(-rng, rng);
+  if (!USE_Y_AS_BUTTONS)
+    Joystick.setYAxisRange(-rng, rng);
 }
 
 int prev_clicked = 0;
@@ -66,9 +73,6 @@ int read_direction(int analog_pin, int base, int max, int rng) {
 }
 
 void loop() {
-  /*int click = get_clicked();
-  if (click) {
-  Mouse.click();}*/
 
   for (int i = 0; i < btn_count; i++) {
     int pin = btn_pins[i];
@@ -82,15 +86,21 @@ void loop() {
   // Analogue input
   int dirx = -read_direction(vrx_pin, base_x, max_x, rng);
   int diry = read_direction(vry_pin, base_y, max_y, rng);
-  if (mouse_mode) {
-    if (diry != 0) {
-      Mouse.move(0, diry, 0);
+  Joystick.setXAxis (dirx);
+  if (USE_Y_AS_BUTTONS) {
+    // first button
+    if (diry >= threshold) {
+      Joystick.setButton(btn_count, HIGH);
+    } else {
+      Joystick.setButton(btn_count, LOW);
     }
-    if (dirx != 0) {
-      Mouse.move(dirx, 0, 0);
+    // second button
+    if (diry <= -threshold) {
+      Joystick.setButton(btn_count+1, HIGH);
+    } else {
+      Joystick.setButton(btn_count+1, LOW);
     }
   } else {
-    Joystick.setXAxis (dirx);
     Joystick.setYAxis (diry);
   }