Radio Frequency Identification (RFID) Card Readers provide a low-cost solution to read passive RFID transponder tags up to 2 inches away. The RFID Card Readers can be used in a wide variety of hobbyist and commercial applications, including access control, automatic identification, robotics navigation, inventory tracking, payment systems, and car immobilization. The RFID card reader read the RFID tag in range and outputs unique identification code of the tag at baud rate of 9600. The data from RFID reader can be interfaced to be read by microcontroller or PC.
RFID Technology Overview
Radio Frequency Identification (RFID) is a generic term for non-contacting technologies that use
radio waves to automatically identify people or objects. There are several methods of identification,
but the most common is to store a unique serial number that identifies a person or object on a
microchip that is attached to an antenna. The combined antenna and microchip are called an “RFID
transponder” or “RFID tag” and work in combination with an “RFID reader” (sometimes called an
An RFID system consists of a reader and one or more tags. The reader’s antenna is used to
transmit radio frequency (RF) energy. Depending on the tag type, the energy is “harvested” by the
tag’s antenna and used to power up the internal circuitry of the tag. The tag will then modulate the
electromagnetic waves generated by the reader in order to transmit its data back to the reader. The
reader receives the modulated waves and converts them into digital data.
There are two major types of tag technologies. “Passive tags” are tags that do not contain their own
power source or transmitter. When radio waves from the reader reach the chip’s antenna, the
energy is converted by the antenna into electricity that can power up the microchip in the tag
(known as “parasitic power”). The tag is then able to send back any information stored on the tag by
reflecting the electromagnetic waves as described above. “Active tags” have their own power
source and transmitter. The power source, usually a battery, is used to run the microchip’s circuitry
and to broadcast a signal to a reader. Due to the fact that passive tags do not have their own
transmitter and must reflect their signal to the reader, the reading distance is much shorter than with
active tags. However, active tags are typically larger, more expensive, and require occasional
service. The Sunrom RFID Card Reader is designed specifically for passive tags.
Frequency refers to the size of the radio waves used to communicate between the RFID system
components. Just as you tune your radio to different frequencies in order to hear different radio
stations, RFID tags and readers must be tuned to the same frequency in order to communicate
There really is no such thing as a “typical” RFID tag. The read range of a tag ultimately depends on
many factors: the frequency of RFID system operation, the power of the reader, environmental
conditions, physical size of the tags antenna and interference from other RF devices. Balancing a
number of engineering trade-offs (antenna size v. reading distance v. power v. manufacturing cost),
the Sunrom RFID Card Reader’s antenna was designed with a RFID operation at a tag read
distance of around 4 inches.
Using RFID Reader
When powered on the RFID reader will activate a RF field waiting for a tag to come into its range.
Once tag is detected, its unique ID number is read and data is sent via serial interface. The valid tag
detecting is indicated by LED blink and Buzzer beep. The face of the RFID tag should be held
parallel to the front of the antenna (where the majority of RF energy is focused). If the tag is held
sideways (perpendicular to the antenna) you may have difficulty getting the tag to be read. Only one
transponder tag should be held up to the antenna at any time. The use of multiple tags at one time
will cause tag collisions and confuse the reader. The tags available with us have a read distance of
approximately 2 inches. Actual distance may vary slightly depending on the size of the transponder
tag and environmental conditions of the application.
Connecting to PC
Use the supplied serial cable to connect to PC’s serial port. Use Hyperterminal software which
comes with Windows XP or use any other Terminal software with following settings.