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Interface RFID With ARM7

Description

Radio-frequency identification(RFID) uses electromagnetic fields to transfer data through wireless.

  • RFID Device consists of two-part
    1.Tag
    2.Reader
  • Tag contain electronically stored information.
  • Information read by the reader.

RFID Tag

  • An RFID system uses the tag, attached to the objects for identification.
  • Readers send a signal to the tag and read its response.
  • Tag is read-only, the tag uses the radio energy transmitted by the reader.
  • Each tag has a unique serial number, by using this tag number it is easy to identify product details.

RFID Reader

  • There are different types of reader available in the market
    1. Passive Reader Active Tag,
    2. Active Reader Passive Tag,
    3. Active Reader Active Tag.

Passive Reader Active Tag

System has a passive reader which only receives radio signals from active tags (battery operated, transmit only).

Active Reader Passive Tag

System has an active reader, which transmits interrogator signals and also receives authentication replies from passive tags.

Active Reader Active Tag

System uses active tags awoken with an interrogator signal from the active reader.

Application

  • Transportation payments.
  • Transportation and logistics.
  • Public transport.
  • Libraries.
  • Hospitals and healthcare.

Hardware Required

  • RFID Reader.
  • RFID Tag.
  • LPC21XX MicroController.

RFID PinOut

  • Vin= +5V.
  • Tx= Rx of Microcontroller.
  • Gnd= Ground.

Circuit

Code

 #include <LPC21xx.H>
 void uart_transmit(unsigned char a);
 void uart_transmit1(unsigned char *a);
 void uart_receive();
 unsigned char rfidcard[];
 void delay();
 int r;
 char k;
 int main()
 {
 VPBDIV=0X02;
 PINSEL0=0X00000005;
 U0LCR=0X83;
 U0DLL=0XC3;
 U0DLM=0X00;
 U0LCR=0X03;
 uart_receive();
 delay();
 uart_transmit1( rfidcard);
 delay();
 }
 void uart_receive()
 {
 while(!(U0LSR & (0X01)));
 r=U0RBR;
 rfidcard[k++]=r;
 }
 void uart_transmit1(unsigned char *a)
 {
 int i=0;
 while(a[i]!='\0')
 {
 U0THR=a[i];
 while(!(U0LSR & 0X20));
 i++;
 }
 }
 void delay()
 {
 int i,j;
 for(i=0;i<1000;i++);
 for(j=0;j<40;j++);
 } 

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