/*
J Paewai 2024
Demo program 10 bit button reader and 8 bit LED using Serial shift registers for inputs and ouputs 
*/
//Outputs 74595 MCU connections
#define clock 4
#define data 5
#define latch 3

//Inputs 74165 MCU Connections
#define clk_7 6
#define sh_cd_1 8
#define data_9 9
#define DATA_WIDTH 16

int pinValues = 0;                     // Store input values of the 2x 74165's
byte outputValue = 0;                  // Current Status of the outputs
int lastPinValues=0;                    // Remember Last key press for Debounce purposes

void data_out(byte dataOut) {          // Sent out a value to the 74595 Serial Resister
  shiftOut(data, clock, LSBFIRST, dataOut );
  shiftOut(data, clock, LSBFIRST, dataOut );
  digitalWrite(latch, LOW);
  delayMicroseconds(1);
  digitalWrite(latch, HIGH);
  delayMicroseconds(1);
  digitalWrite(latch, LOW);
}

int read_shift_register()              // Read in the shift register of the input keys
{
  byte bitVal;
  int bytesVal = 0;
  digitalWrite(sh_cd_1, LOW);
  delayMicroseconds(5);
  digitalWrite(sh_cd_1, HIGH);
  for (int i = 0; i < DATA_WIDTH; i++)
  {
    bitVal = digitalRead(data_9);
    bytesVal |= (bitVal << ((DATA_WIDTH - 1) - i));
    digitalWrite(clk_7, HIGH);
    delayMicroseconds(5);
    digitalWrite(clk_7, LOW);
  }
  return (bytesVal);
}

byte whichKeyPressed(int rawValue) { // returns a number between 1-10 of the key pressed (only one at a time)
  byte retVal = 0;
  switch (rawValue) {
    case 512: retVal = 10; data_out(0); break;            // Toggle bit 1
    case 256: retVal = 9;  data_out(255); break;          // Toggle bit 1
    case 128: retVal = 8;  data_out(rawValue); break;     // Toggle bit 8
    case 64: retVal = 7;   data_out(rawValue); break;     // Toggle bit 7
    case 32: retVal = 6;   data_out(rawValue); break;     // Toggle bit 6
    case 16: retVal = 5;   data_out(rawValue); break;     // Toggle bit 5
    case 8: retVal = 4;    data_out(rawValue); break;     // Toggle bit 4
    case 4: retVal = 3;    data_out(rawValue); break;     // Toggle bit 3
    case 2: retVal = 2;    data_out(rawValue); break;     // Toggle bit 2 
    case 1: retVal = 1;    data_out(rawValue); break;     // Toggle bit 1
  }
  return retVal;
 }

void setup() {
//outputs 74595 MCU setups
 pinMode(data,OUTPUT);
 pinMode(clock,OUTPUT);
 pinMode(latch,OUTPUT);
 //inputs 74165 x2 MCU setups
 pinMode(clk_7,OUTPUT);
 pinMode(sh_cd_1,OUTPUT);
 pinMode(data_9,INPUT);
 outputValue = 0;   // Value to contains the output status since we cannot read it
 data_out(0);       // Ensure All outputs are off
}

void loop (){
  pinValues = read_shift_register();               // check for key press
  if(lastPinValues != pinValues && pinValues!=0) { // Is register empty or the same key still held down?
  byte KP = whichKeyPressed(pinValues);
   outputValue = pinValues;
   lastPinValues = pinValues;
   delay(10);  // Small debounce delay
  } 
  
}