134.2Khz RFID Long Distance Animal Tag Reader Module FDX ISO11784/85 compatible Arduino

https://github.com/SensorsIot/Animal-RFID-Reader/blob/master/Animal_RFID_Reader/Animal_RFID_Reader.ino

char message[35];
unsigned long lastSignal = 0;
bool transmission = false;
byte state = 1;
int pos;

#define GREENPIN 10
#define REDPIN 9

unsigned long dishka = 8;
unsigned long dishkaFake = 1532661448;

void setup() {
Serial.begin(9600);
Serial2.begin(9600);
pinMode(GREENPIN, OUTPUT);
digitalWrite(GREENPIN, HIGH);
pinMode(REDPIN, OUTPUT);
digitalWrite(REDPIN, HIGH);
Serial.println(“Start”);
lastSignal = millis();
}

void loop() {
switch (state) {
case 1: {

if (Serial2.available() > 0) {
lastSignal = millis();
pos = 0;
state = 2;
}
break;
}
case 2: {
// Reading of message
if (Serial2.available() > 0 && pos 100) state = 3;
if (pos >= 35) {
delay(300);
state = 1;
}
}
break;
case 3: {
// checksum
Serial.println();
byte check = message[1];
for (int i = 2; i < 27; i++) {
check = check ^ message[i];
}
Serial.println();
// Serial.print(check);
// Serial.print(",");
// Serial.println(message[27], HEX);
if (check == message[27]) {
// Serial.println("Check OK");

// Decodung
unsigned long id = hexInDec(message, 1, 10);
int countryNbr = hexInDec(message, 11, 4);

Serial.print("CardNumber=");
Serial.println(id);
Serial.print("Country=");
Serial.println(countryNbr);

if (id == dishka || id == dishkaFake) {
digitalWrite(GREENPIN, LOW);
digitalWrite(REDPIN, HIGH);
Serial.println("It is Dishka!");
} else {
digitalWrite(GREENPIN, HIGH);
digitalWrite(REDPIN, LOW);
Serial.println("It is not Dishka!");
}
state = 4;
}
break;
}
case 4: {
delay(2000);
digitalWrite(GREENPIN, HIGH);
digitalWrite(REDPIN, HIGH);
state = 1;

break;
}
} //switch
}

unsigned long hexInDec(char message[], int beg , int len) {
unsigned long mult = 1;
unsigned long nbr = 0;
byte nextInt;

for (int i = beg; i = 48 && nextInt = 65 && nextInt = 97 && nextInt <= 102) nextInt = map(nextInt, 97, 102, 10, 15);
nextInt = constrain(nextInt, 0, 15);
nbr = nbr + (mult * nextInt);
mult = mult * 16;
}
return nbr;
}