#include <Arduino.h>

const uint8_t NODES[8] = {2, 3, 4, 5, 6, 7, 8, 9}; // D2–D9 = P0–P7

struct Pair { uint8_t hi, lo; };

// === Build 44 LED pairs (hi ≠ lo), in order ===
const int NUM_LEDS = 44;
Pair LEDS[NUM_LEDS];

void buildCharlieplexMap() {
  int index = 0;
  for (int i = 0; i < 8 && index < NUM_LEDS; i++) {
    for (int j = 0; j < 8 && index < NUM_LEDS; j++) {
      if (i != j) {
        LEDS[index++] = {NODES[i], NODES[j]};
      }
    }
  }
}

void setHighZ() {
  for (uint8_t i = 0; i < 8; i++) {
    pinMode(NODES[i], INPUT);
  }
}

void lightLED(Pair p) {
  setHighZ();
  pinMode(p.hi, OUTPUT);
  pinMode(p.lo, OUTPUT);
  digitalWrite(p.hi, HIGH);
  digitalWrite(p.lo, LOW);
}

void setup() {
  buildCharlieplexMap();
}

void loop() {
  for (int i = 0; i < NUM_LEDS; i++) {
    lightLED(LEDS[i]);
    delayMicroseconds(300);  // Fast scanning = all appear ON
  }
}