Joystick bar graph on an Arduino Uno

// Bar graph: a thumb stick's X axis drawn on eight LEDs.
//
//   pins 2..9  eight LEDs, each through 220 ohm to GND, left to right
//   A0         the stick's VRX        A1  its VRY
//   pin 12     the stick's SW, to GND, internal pull-up
//
// analogRead gives 0..1023 for 0 to 5 V, and map() turns that into 0..8 lamps.
// That is the whole of a bar graph: the meter is the arithmetic, the LEDs are
// just where the answer is written down.
//
// Press the stick and the bar switches to the Y axis, so the same eight lamps
// read the other pot. The mode is printed when it changes, so the serial
// monitor says which axis you are looking at.
//
// A stick does not spring back to exactly 512, and the driver in
// mokxi_joystick.h samples where it rests at begin() and measures from there.
// Here the raw reading is what is wanted (the bar should be half lit when
// the stick is centered), so this one calls x() and y() rather than dx()
// and dy().

#include "mokxi_joystick.h"

const int LED_PINS[] = {2, 3, 4, 5, 6, 7, 8, 9};
const int LEDS = 8;

Joystick stick(A0, A1, 12);

bool useY = false;

static void bar(int lit) {
  for (int i = 0; i < LEDS; i++) {
    digitalWrite(LED_PINS[i], i < lit ? HIGH : LOW);
  }
}

void setup() {
  for (int i = 0; i < LEDS; i++) {
    pinMode(LED_PINS[i], OUTPUT);
  }
  stick.begin();
  Serial.begin(115200);
  Serial.println("Mokxi Arduino Uno: joystick bar graph");
  Serial.println("push the stick left and right; press it to swap axis");
}

void loop() {
  if (stick.clicked()) {
    useY = !useY;
    Serial.print("reading the ");
    Serial.println(useY ? "Y axis" : "X axis");
  }

  int raw = useY ? stick.y() : stick.x();
  int lit = (int)map(raw, 0, 1023, 0, LEDS);
  if (lit > LEDS) {
    lit = LEDS;
  }
  bar(lit);

  static int last = -1;
  if (lit != last) {
    last = lit;
    Serial.print(useY ? "Y " : "X ");
    Serial.print(raw);
    Serial.print(" -> ");
    Serial.print(lit);
    Serial.println(" lamps");
  }

  delay(40);
}