/*
  74HC165 Shift register input with buttons example
  https://wokwi.com/projects/461142583144035329
  AnonEngineering 4/26
*/

const int DATA_PIN  = 2;  // data out (Q7)
const int CLK_PIN   = 3;  // clock (CP)
const int LATCH_PIN = 4;  // latch (PL)
const int NUM_BITS = 8;   // set to 8 * number of shift registers

int oldResult = 0;

void printBits(byte data) {
  Serial.print("   Bits: ");
  for (int i = 7; i >= 0; i--) {
    Serial.print(bitRead(data, i));
  }
  //Serial.println();
}

void setup() {
  Serial.begin(115200);
  pinMode(DATA_PIN, INPUT);
  pinMode(CLK_PIN, OUTPUT);
  pinMode(LATCH_PIN, OUTPUT);
}

void loop() {
  int result = 0;
  int btnNumber = 0;

  // latch inputs
  digitalWrite(LATCH_PIN, LOW);
  digitalWrite(LATCH_PIN, HIGH);
  // shift bits
  for (int i = 0; i < NUM_BITS; i++) {
    int bit = digitalRead(DATA_PIN);
    result += bit << i;
    digitalWrite(CLK_PIN, HIGH); // Shift out the next bit
    digitalWrite(CLK_PIN, LOW);
  }
  // show results if changed (and not 0)
  if (result != oldResult && result != 0) {
    oldResult = result;
    for (int i = 0; i < 8; i++) {
      if (bitRead(result, i) == HIGH)  {
        btnNumber = 8 - i;
      }
    }
    Serial.print("Button: ");
    Serial.print(btnNumber);
    printBits(result);
    Serial.print("   Decimal: ");
    Serial.println(result);
  }
  //delay(1000);
}