28140 Parallax Inc, 28140 Datasheet - Page 6

• Manufacturer Part Number: 28140
• Description: READER MODULE RFID
• Manufacturer: Parallax Inc

Specifications of 28140

• Rf Type: Read Only
• Frequency: 125kHz
• Features: Single 5V Power Supply
• Package / Case: Module
• Product: Microcontroller Accessories
• Data Bus Width: 8 bit
• Clock Speed: 125 KHz
• Interface Type: USB
• Operating Supply Voltage: 5.5 V
• Board Size: 46.99 mm x 69.22 mm x 21.84 mm
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant, Lead free / RoHS Compliant

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.
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 effectively. RFID
systems typically use one of the following frequency ranges: low frequency (or LF, around 125 kHz), high
frequency (or HF, around 13.56 MHz), ultra-high frequency (or UHF, around 868 and 928 MHz), or
microwave (around 2.45 and 5.8 GHz).
The read range of a tag ultimately depends on many factors: the frequency of RFID system operation,
the power of the reader, and interference from other RF devices. Balancing a number of engineering
trade-offs (antenna size v. reading distance v. power v. manufacturing cost), the Parallax RFID Card
Reader's antenna was designed specifically for use with low-frequency (125 kHz) passive tags with a read
distance of around 4 inches.
BASIC Stamp
The following code examples read tags from a RFID Card Reader and compare the values to known tags
(stored in an EEPROM table).
' =========================================================================
'
'
'
'
'
'
'
'
'
'
'
' =========================================================================
' -----[ Program Description ]---------------------------------------------
'
' Reads tags from a Parallax RFID reader and compares to known tags (stored
' in EEPROM table).
' -----[ Revision History ]------------------------------------------------
' -----[ I/O Definitions ]-------------------------------------------------
SYMBOL
SYMBOL
SYMBOL
SYMBOL
' -----[ Constants ]-------------------------------------------------------
SYMBOL
' -----[ Variables ]-------------------------------------------------------
Copyright © Parallax Inc.
File....... RFID.BS1
Purpose.... RFID Tag Reader / Simple Security System
Author..... (c) Parallax, Inc. -- All Rights Reserved
E-mail..... [e-mail]
Started....
Updated.... 07 FEB 2005
{$STAMP BS1}
{$PBASIC 1.0}
Enable
RX
Spkr
Latch
LastTag
®
1 Program
If tag is found, the program will disable a lock.
= 0
= 1
= 2
= 3
= 2
RFID Card Reader Serial & USB (#28140 / 28340)
' low = reader on
' serial from reader
' speaker output
' lock/latch control
' 3 tags; 0 to 2
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