// Source: https://www.aliexpress.com/item/Free-shipping-UART-125Khz-EM4100-RFID-Card-Key-ID-Reader-Module-RDM6300-RDM630-For-Arduino/32279622758.html

/*

Module: EM4100



Frequency: 125KHZ
- Baud rate: 9600
- Interface:
TTL level RS232 format
- Working voltage:
DC 5V(+/-5%)
- Working current:
<50mA
- Receive distance: 20~50mm
- Working temperature:
-10°C~+70°C
- Storage temperature:
-20°C~+80°C
- Humidity: 0~95%
- Wiring size: 46*32*3mm

- PCB size: 38.5*19*9mm
ple code:
*/

String comdata = "";
void setup()
{
    pinMode(2,OUTPUT);
    pinMode(3,OUTPUT);
    digitalWrite(2,HIGH);
    digitalWrite(3,HIGH);
    Serial.begin(9600);
}

void loop()
{

    digitalWrite(2,HIGH);
    digitalWrite(3,HIGH);
    while (Serial.available() > 0)
    {
        comdata += char(Serial.read());
        delay(2);
    }
    if(comdata.length() > 0&&comdata=="0500ADDF1443")
    {
        while( comdata.length() > 0 )
        {
            digitalWrite(3,LOW);
            delay(100);
            while (Serial.available() > 0)
            {
                comdata += char(Serial.read());
                delay(2);
            }
            comdata = "";
        }
    }
    else if (comdata.length() > 0)
    {
        while(comdata.length() > 0)
        {
            digitalWrite(2,LOW);
            delay(100);
            while (Serial.available() > 0)
            {
                comdata += char(Serial.read());
                delay(2);
            }

            comdata = "";
        }
    }
}