A simple library to interface with Gwiot 7941E RFID reader. Based on rdm6300 library by Arad Eizen.

• Fast and single tag reading
• Using a single configurable GPIO pin
• Both Hardware and Software UART (Serial) support on ESP8266
• Both SoftwareSerial and AltSoftSerial support

• Gwiot 7941E module
• 125kHz RFID tags
• Microcontroller (Arduino, ESP8266, ESP32...)
• Jump-Wires (resistors of 1k and 2k if you are using a 3.3V based microcontroller).

A simple RFID tag reader with textual Serial output: examples/read_to_serial/read_to_serial.ino

#include <Gwiot7941e.h>

#define GWIOT_7941E_RX_PIN 4
Gwiot7941e gwiot7941e;

void setup()
{
    //...
    gwiot7941e.begin(GWIOT_7941E_RX_PIN);
    //...
}

void loop()
{
    //...
    if (gwiot7941e.update()) {
        Serial.println(gwiot7941e.getLastTagId(), HEX);
    }
    //...
}

• void begin(Stream *stream) - Initialize the object to use the given Stream (i.e. an AltSoftSerial object) to read from the 7941E.
• void begin(int rxPin, uint8_t uartNum=1) - Initialize the object to use the given GPIO pin as RX from the 7941E. Use uartNum to specify which Serial to use on ESP8266/ESP32.
• bool update() - Updates the internal values by reading from the 7941E, returns true on tag detection, must be called repeatedly!
• uint32_t getLastTagId() - Returns the last tag id read by update().

Here are some additional resources about the Gwiot 7941E RFID reader.

• Module datasheet (in chinese)
• Output data format (by QuickFix): https://www.esp8266.com/viewtopic.php?t=18447
• Support code for the module (by Pako2): esprfid/esp-rfid#196