Web Site: www.parallax.com Office: (916) 624-8333 Forums: forums.parallax.com Fax: (916) 624-8003 Sales: sales parallax.com Sales: (888) 512-1024 Technical: support parallax.com Tech Support: (888) 997-8267 RFID Card Reader, Serial ( 28140) RFID Card Reader, USB ( 28340) Introduction Designed in cooperation with Grand Idea Studio (www.grandideastudio.com), the Parallax Radio Frequency Identification (RFID) Card Readers provide a low-cost solution to read passive RFID transponder tags up to 4 inches away. The RFID Card Readers can be used in a wide variety of hobbyist and commercial applications, including access control, user identification, robotics navigation, inventory tracking, payment systems, car immobilization, and manufacturing automation. The RFID Card Reader is available in two versions: A TTL-level serial interface for use with a microcontroller and a USB interface for direct connection to a computer. Features y Low-cost method for reading passive, 125 kHz RFID transponder tags y Two easy-to-use versions: Serial interface for microcontrollers and USB for direct connection to PC, Macintosh, or Linux machines y Bi-color LED for visual indication of status Copyright Parallax Inc. RFID Card Reader Serial & USB ( 28140 / 28340) v2.2 3/22/2010 Page 1 of 11 RFID Compatibility The Parallax RFID Card Reader works exclusively with the EM Microelectronics EM4100-family of passive 40 read-only transponder tags. Each transponder tag contains a unique, read-only identifier (one of 2 , or 1,099,511,627,776 possible combinations). A variety of different tag types and styles exist with the most popular made available from Parallax. Connections (Serial) The Parallax RFID Card Reader Serial version easily interfaces to any host microcontroller using only four connections (VCC, /ENABLE, SOUT, GND). Pin Pin Name Type Function 1 VCC P System power. +5V DC input. Module enable pin. Active LOW digital input. Bring this pin LOW to 2 /ENABLE I enable the RFID reader and activate the antenna. Serial output to host. TTL-level interface, 2400 bps, 8 data bits, no parity, 3 SOUT O 1 stop bit. 4 GND G System ground. Connect to power supplys ground (GND) terminal. Note: Type: I = Input, O = Output, P = Power, G = Ground Use the following example circuit for connecting the Parallax RFID Card Reader: Copyright Parallax Inc. RFID Card Reader Serial & USB ( 28140 / 28340) v2.2 3/22/2010 Page 2 of 11