/* RS 485-Implementierung, die sowohl Schreiben als auch Lesen kann */
/* Basis für andere Projekte */

#define BUTTON 2
#define RECEIVE 3
#define RECEIVE_ENABLE 4
#define SEND 5
#define SEND_ENABLE 6

#define MAX_LEN 128

void setup() {
  // Buttons connected to analog input lines
  pinMode(A0,INPUT_PULLUP);
  pinMode(A1,INPUT_PULLUP);
  pinMode(A2,INPUT_PULLUP);
  pinMode(A3,INPUT_PULLUP);
  pinMode(A4,INPUT_PULLUP);
  pinMode(A5,INPUT_PULLUP);
  pinMode(A6,INPUT_PULLUP);
  pinMode(A7,INPUT_PULLUP);
  // Currently, all buttons are also connected via a diode to an interruptable pin, to notify on input changes.
  // This interruptable pin should be assgined to BUTTON
  pinMode(BUTTON,INPUT_PULLUP);
  attachInterrupt(digitalPinToInterrupt(BUTTON),button,FALLING); // interrupt for button change

  // Set up pins for RS485 connection
  pinMode(RECEIVE, INPUT);
  pinMode(RECEIVE_ENABLE, OUTPUT);
  pinMode(SEND, OUTPUT);
  pinMode(SEND_ENABLE, OUTPUT);
  attachInterrupt(digitalPinToInterrupt(RECEIVE),receive,CHANGE); // interrupt for incoming RS485 traffic
  
  reset485();
  buttons = 0x0;
}

void button() {
  buttons = 0xFF ^ (digitalRead(A7)<<7 | digitalRead(A6)<<6 | digitalRead(A5)<<5 | digitalRead(A4)<<4 | digitalRead(A3)<<3 | (!digitalRead(A2))<<2 | digitalRead(A1)<<1 | digitalRead(A0));  
}

void receive(){
  bool received_bit = digitalRead(RECEIVE);
  curr = micros();
  duration = curr - last;
  Serial.print("Input switched to ");
  Serial.print(received_bit?"H":"L");  
  Serial.print(" after ");
  Serial.print(duration);
  Serial.println(" ticks");
  last = curr;
  if (duration > MAX_TICKS) reset485();
  received_bit = !received_bit; // received_bit is the current value, the duration of the previous value (=inverted) has been measured
  duration /= BASE;
  while (duration > 0){
    byte_idx--;
    recv |= received_bit<<byte_idx;
    if (byte_idx == 0) {
      msg[msg_idx] = recv;
      msg_idx++;
      byte_idx = 8;
      if (recv == 0x00) message_received();
    }
    duration--;
  }
}

void reset485(){
  byte_idx = 8;
  msg_idx = 0;
  recv=0x0;
}

void message_received(){
  for (int i=0; i<MAX_LEN; i++) message[i]=msg[i];
  reset485();
}

void button_pressed(int i){
  Serial.println("not implemented");
}

void loop(){
  if (buttons>0){
    for (int i=0; i<7; i++){
      if (buttons & (1<<i)) button_pressed(i);     
    }    
  }
  if (message[0] != 0x0){
    Serial.print("Received '");
    Serial.print(message);
    Serial.println("'");    
    message[0] = 0x0;
  }
}