// Echo in C and C++ with pushbutton rest
// Recreated By Faisal
// 22-March-2020

#include <avr/io.h>
#include <SoftwareSerial.h>

const int rxPin = 0;
const int txPin = 1;
const int led = 3;  // Make sure that is the program is running
const int button = 7; //Disabled for dynamic memory
int PBval = 0; // reading pushbutton pin status
const int debounce = 300;// debounce for pushbutton
const int max_buffer = 25; // Buffer index size
boolean newData = false; // Check new data

// Prepare Serila with Tx, Rx Pins
SoftwareSerial mySerial(rxPin, txPin); // RX, TX

void setup() {
  pinMode (led, OUTPUT);
  pinMode (button, INPUT);
  PINA |= (1 << PINA7); // 1 to use internal pull-up resitor to pin A7, 0 to use external

  // define pin modes for tx, rx:
  pinMode(rxPin, INPUT);
  pinMode(txPin, OUTPUT);
  // Initialize Serial
  mySerial.begin(115200);
  delay(3000); // To see the message when open the monitor via FTDI cable
  mySerial.println("<Echo is ready>");
  digitalWrite(led, LOW);
}

void loop() {
  // Static variables persist beyond the function call,
  // preserving their data between function calls.
  // Unlike local variables that get created and
  // destroyed every time a function is called
  static char chr;
  static char buffer[max_buffer] = {0};
  static int index;
  PBval = digitalRead (button);
  if (PBval == LOW) {
    delay(debounce);
    digitalWrite(led, HIGH);
    mySerial.println("Clear Buffer");
    index = 0;
    while (index <= 25) {
      buffer[index] = 0;
      delay(8.5);
      ++index;
    }
    index = 0;
    digitalWrite(led, LOW);
  }
  // Check if serial is ready, with new data:
  if (mySerial.available() > 0) {
    // read the incoming byte:
    delay(50);
    chr = mySerial.read();
    newData = true;
  }
  // Print out the new data:
  if (newData == true) {
    buffer[index] = chr;
    delay(8.5);
    // say what you got:
    mySerial.println(buffer);
    ++index;
    newData = false;
  }
  // Reset the buffer for manage the memory
  if (index == 25) {
    index = 0;
    while (index <= 25) {
      buffer[index] = 0;
      delay(8.5);
      ++index;
    }
    index = 0;
  }

}