struct Message {
  uint16_t Uniek;
  uint8_t BoardNo;
  uint16_t Command;
  uint16_t Argument;
  uint16_t ArgumentExt;
  uint8_t ArgumentSmall;
  byte Values[4];
};

const uint16_t None = 0;
const uint16_t Nano_CH340 = 5;
const uint16_t Identifier = 8324;
bool IsActive = false;
const uint16_t ErrorUniek = 1;
const uint16_t ErrorCommandNotDefined = 14;

const uint8_t BoardNr = 1;

const uint16_t CmdGetDefinition = 1;
const uint16_t CmdTest = 2;
const uint16_t CmdError = 13;

void setup() {
  Serial.begin(9600);
  IsActive = false;
}

void loop() {
  struct Message msg;

  if (Serial.available() > 0) {
    Serial.readBytes((uint8_t *)&msg, sizeof(msg));

    if (msg.Uniek == Identifier) {
      switch (msg.Command)
      {
        case CmdGetDefinition:
          GetDefinition();
          break;
        case CmdTest:
          SendTest();
          break;
        default:
          SendError(ErrorCommandNotDefined, msg.Command);
          break;
      }
    }
    else
    {
      SendError(ErrorUniek, 0);
    }
  }
}

void SendTest()
{
  struct Message msg;
  memset(&msg, 255, sizeof( msg)) ;

  msg.Uniek = Identifier;
  msg.BoardNo = BoardNr;
  msg.Command = CmdTest;
  msg.Argument =1000;
  msg.ArgumentExt = 1001;
  msg.ArgumentSmall = 100;
  msg.Values[0] = 10;
  msg.Values[1] = 11;
  msg.Values[2] = 12;
  msg.Values[3] = 13;

  Serial.write((const uint8_t *)&msg, sizeof(msg));
}

void SendError(int error, int parms)
{
  struct Message msg;
  memset(&msg, 255, sizeof( msg)) ;

  msg.Uniek = Identifier;
  msg.BoardNo = BoardNr;
  msg.Command = CmdError;
  msg.Argument = error;
  msg.ArgumentExt = parms;

  Serial.write((const uint8_t *)&msg, sizeof(msg));
}

void GetDefinition()
{
  struct Message msg;
  memset(&msg, 255, sizeof( msg)) ;

  msg.Uniek = Identifier;
  msg.BoardNo = BoardNr;
  msg.Command = CmdGetDefinition;
  msg.Argument = Nano_CH340;
  Serial.write((const uint8_t *)&msg, sizeof(msg));
  IsActive = true;
}