Penti chorded keyboard emulation for one half of the Let's Split 40% mech keyboard

penti.ino

#include <Keyboard.h>

#define ROW_NUM 5
#define COL_NUM 6

byte row_pins[5] = { 4, 6, 7, 8, 9 };
byte col_pins[6] = { 10, 16, 14, 15, 18, 19};

byte fingers[5][2] = {{4, 2},{3, 2}, {2, 2}, {1, 2}, {0, 4}}; // [col, row]
char finger_keys[5] = {'A', 'B', 'C', 'D', 'E'};

void setup() {
  Serial.begin(9600);
}

char Penti[32] = {
   0, 'N', 'I', 'G', 'E', 0, 'O', 'M',
   'S', 'J', 'C', 'V', 'L', 0, 'U', 'K',
   ' ', 'D', 'A', 'Y', 'R', 0, 'B', 'T',
   'F', 'H', 'Q', 'X', 'Z', 0, 'P', 'W'
};

void scan () {
  static byte state;
  byte newState = 0;

  for (byte finger = 0; finger < 5; finger++){
    byte col = fingers[finger][0];
    byte row = fingers[finger][1];
    
    pinMode(row_pins[row], OUTPUT);
    digitalWrite(row_pins[row], LOW);
    pinMode(col_pins[col], INPUT_PULLUP);

    delayMicroseconds(30);
    
    if (digitalRead(col_pins[col]) == LOW) {
      newState = newState | (1 << finger);
    }

    pinMode(row_pins[row], INPUT_PULLUP);
  }

  if (newState == 0 && state != 0) { // Release
    Keyboard.write(Penti[state]);
    state = 0;
  } else {
    state = state | newState;
  }
}

void loop() {
  scan();
}