Grove - 125KHz RFID Reader

From Wiki
Jump to: navigation, search


This Grove-125KHz RFID Reader is a module used to read uem4100 RFID card information with two output formats: Uart and Wiegand. It has a sensitivity with maximum 7cm sensing distance. There is also the electronic brick version of this module. It can help you with project like internet of thing and access control system.


And you should use these module below while using RFID reader:

RFID tag combo (125khz)

Specifications Voltage: 4.75-5.25V Working Frequency: 125 KHz Sensing Distance(Max): 70mm TTL Output: 9600 baudrate, 8 data bits, 1 stop bit, and no verify bit Wiegand Output: 26 bits Wiegand format, 1 even verify bit, 24 data bits, and 1 odd verify bit

Demonstration Here we show how to read RFID information using the Grove - 125KHz RFID Reader. Connect Grove - 125KHz RFID Reader to UART of Grove - Base Shield.


Uart Mode (Jumper set to the left two pins)You would need to select the jumper to "U" to enter this mode, and the setting is: 9600bps, N, 8, 1, TTL output

// link between the computer and the SoftSerial Shield //at 9600 bps 8-N-1 //Computer is connected to Hardware UART //SoftSerial Shield is connected to the Software UART:D2&D3

  1. include <SoftwareSerial.h>

SoftwareSerial SoftSerial(2, 3); unsigned char buffer[64]; // buffer array for data receive over serial port int count=0; // counter for buffer array void setup() {

 SoftSerial.begin(9600);               // the SoftSerial baud rate   
 Serial.begin(9600);             // the Serial port of Arduino baud rate.


void loop() {

 if (SoftSerial.available())              // if date is coming from software serial port ==> data is coming from SoftSerial shield
   while(SoftSerial.available())          // reading data into char array 
     buffer[count++];     // writing data into array
     if(count == 64)break;
   Serial.write(buffer,count);            // if no data transmission ends, write buffer to hardware serial port
   clearBufferArray();              // call clearBufferArray function to clear the stored data from the array
   count = 0;                       // set counter of while loop to zero

 if (Serial.available())            // if data is available on hardware serial port ==> data is coming from PC or notebook
   SoftSerial.write(;       // write it to the SoftSerial shield

} void clearBufferArray() // function to clear buffer array {

 for (int i=0; i<count;i++)
   { buffer[i]=NULL;}                  // clear all index of array with command NULL

} Open the Serial Monitor, the card information can be display as show below:


Wiegand Mode (Jumper Set to the Right two Pins) You would need to select the jumper to "W" to enter this mode. The Wiegand demo code for Seeeduino is designed to read Wiegand data in interrupt mode.

In Wiegand Mode, output data is formatted with 26bits including 24bits card info and 2 bits parity.

bit 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 - PE D P0 - - E 0 - - - D2[7..0] D1[7..0] D0[7..0] -

PE is even bit, PO is odd bit; E is the data bit which was involved in even, O is the data bit which was involved in odd; DX[7..0] is the data bit which correspond to Mifare@ Standard & Light card read only ID;