KEELOQ® Code Hopping Encoder Product Brief* Security Program

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KEELOQ® Code Hopping Encoder Product Brief* Security Program

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HCS200
KEELOQ® Code Hopping Encoder Product Brief*
Security
Programmable 28-bit serial number Programmable 64-bit encryption Each transmission unique 66-bit transmission code length 32-bit hopping code 28-bit serial, 4-bit function VLOW indicator transmitted Encryption read protected
PACKAGE TYPES
PDIP, SOIC
BLOCK DIAGRAM
Oscillator Reset circuit Controller Power latching switching
Operating
Three button inputs additional circuitry required Seven functions available Selectable baud rate Automatic code word completion Nonvolatile synchronization data
EEPROM
Encoder
Other
Easy-to-use programming interface On-chip EEPROM On-chip oscillator timing components Button inputs have internal pulldown resistors On-chip reset circuit
32-bit shift register
Button input port
Typical Applications
Automotive remote entry systems Automotive alarm systems Automotive immobilizers Gate garage door openers Electronic door locks/access control Burglar alarm systems
HCS200 combines 32-bit hopping code generated non-linear encryption algorithm, with 28-bit serial number information bits create 66-bit transmission stream. length transmission eliminates threat code scanning code hopping mechanism makes each transmission unique, thus rendering code capture resend schemes useless. encryption key, serial number configuration data stored EEPROM, which programmed using simple serial interface. EEPROM cannot read means unless erased first. This protects against attempts gain access memory array makes HCS200 very secure unit. HCS200 operates over wide voltage range volts volts three functional inputs 8-pin configuration. This gives system designer freedom have seven functions without adding additional circuitry.
DESCRIPTION
Microchip Technology Inc. HCS200 code hopping encoder designed secure remote keyless entry systems. HCS200 utilizes KEELOQ® code hopping algorithm incorporates high security, small package outline cost make this device perfect solution unidirectional remote keyless entry (RKE) systems.
KEELOQ registered trademark Microchip Technology Inc. *Code hopping encoder patents allowed pending.
1996 Microchip Technology Inc.
Advanced Information
This document created with FrameMaker
DS40134A-page
HCS200
DEVICE OPERATION
Terms
FIGURE 1-2:
ENCODER OPERATION
button been pressed)
POWER
Manufacturer's 64-bit word unique each manufacturer used produce unique secret each encoder. Secret unique 64-bit encryption generated from manufacturers encoder serial number used encryption. Learn ability decoder learn information about encoder that future transmissions recognized validated. shown Figure 1-1, HCS200 simple use. requires only addition buttons circuitry transmitter your security application. high security level HCS200 based KEELOQ encryption algorithm. KEELOQ block cipher based block length bits length bits. algorithm obscures information such that even transmission information (before coding) differs only from information previous transmission, next coded transmission will totally different. essence, only 32-bit string information changes, least percent coded transmission will change. indicated Figure 1-2, HCS200 will wake upon detecting switch closure then delay 10ms switch debounce. switch information together with secret will encrypted using KEELOQ algorithm create encrypted portion transmission. encrypted code hopping portion transmission will change every time, even same button pushed again. code that been transmitted will occur again more than 65,000 transmissions. This will provide more than years typical before code repeated.
RESET DEBOUNCE DELAY
(10MS)
SAMPLE INPUTS
UPDATE SYNC INFO ENCRYPT WITH SECRET
LOAD TRANSMIT REGISTER TRANSMIT
BUTTON ADDED
BUTTONS RELEASED
STOP
Programming HCS200
FIGURE 1-1:
TYPICAL APPLICATION CIRCUIT
HCS200 EEPROM must programmed before use. Programming device done using simple serial interface using pins HCS200 clock data. When programming cycle entered, EEPROM values erased verification stored values possible until after programming cycle complete. These features prevent unauthorized access stored values.
Button Information
Buttons Activated Function Transmitted
Description Standby Code Transmission
button remote control
Fixed/Seed Transmission
DS40134A-page
Advanced Information
1996 Microchip Technology Inc.
HCS200
FIGURE 1-3: CODE WORD TRANSMISSION FORMAT
LOGIC
LOGIC Pulse Period Preamble Header Encrypted Portion Transmission Fixed portion Transmission Guard Time
Code Word Transmission
Transmission Format
Synchronization
indicated Figure 1-3, 66-bit transmitted word consists fixed 34-bit portion 32-bit encrypted data portion. encrypted portion provides four billion changing code combinations includes function bits along with synchronization data indiscriminate random numbers. fixed portion comprised status bits, function bits (based which buttons were activated), portion serial number. fixed encrypted sections combined increase number combinations 7.38 1019.
Decoder Operation*
HCS200 system requires compatible decoder device receiver system. This typically microcontroller with compatible firmware which provided under license agreement from Microchip. Microchip's PIC16/17 microcontroller line provides user with large choice devices that perform decoding functions well handle system needs customer. order transmitter used with decoder, transmitter must first `learned', unless encoder decoder factory programmed with corresponding sets. When transmitter learned decoder, decoder stores serial number current synchronization value EEPROM. After learn mode entered, decoder must receive consecutive valid transmissions from same encoder before learn values stored. decoder must keep track these values every transmitter that learned. decoder must also store manufacturer's code order learn transmitter. secret used decode code hopping portion transmission.
KEELOQ algorithm features sophisticated synchronization technique which does require recalculation future codes. decoder will track next expected synchronization value values after that. these values received, then command will executed. some reason function button pushed more than sixteen times while range decoder, synchronization will lost. However, synchronization will automatically restored when decoder receives successive codes. decoder misses more than 32,000 transmissions, would necessary relearn transmitter. Since entire window rotates after each valid transmission, past codes invalid which eliminates possibility grabbing previous code retransmitting gain entry.
Fixed/Seed Transmission
When S2=S1=S0=1, 32-bit code hopping bits replaced bits stored EEPROM locations eight nine, resulting 6-bit fixed-code transmission. This normally used seed transmission during secure learn.
Features Different from HCS300
3-button inputs 4-button inputs envelope encryption time-out repeat indicator transmitted word overflow bits VLOW indicator approximately volts
Encoder decoder operation patents allowed pending.
1996 Microchip Technology Inc.
Advanced Information
DS40134A-page
WORLDWIDE SALES SERVICE
AMERICAS
Corporate Office Microchip Technology Inc. 2355 West Chandler Blvd. Chandler, 85224-6199 Tel: 786-7200 Fax: 786-7277 Technical Support: 786-7627 Web: http://www.mchip.com/microchip Atlanta Microchip Technology Inc. Sugar Mill Road, Suite 200B Atlanta, 30350 Tel: 640-0034 Fax: 640-0307 Boston Microchip Technology Inc. Mount Royal Avenue Marlborough, 01752 Tel: 480-9990 Fax: 480-8575 Chicago Microchip Technology Inc. Pierce Road, Suite Itasca, 60143 Tel: 285-0071 Fax: 285-0075 Dallas Microchip Technology Inc. 14651 Dallas Parkway, Suite Dallas, 75240-8809 Tel: 991-7177 Fax: 991-8588 Dayton Microchip Technology Inc. Suite Prestige Place Miamisburg, 45342 Tel: 291-1654 Fax: 291-9175 Angeles Microchip Technology Inc. 18201 Karman, Suite 1090 Irvine, 92715 Tel: 263-1888 Fax: 263-1338 York Microchip Technology Inc. Motor Parkway, Suite Hauppauge, 11788 Tel: 273-5305 Fax: 273-5335 Jose Microchip Technology Inc. 2107 North First Street, Suite Jose, 95131 Tel: 436-7950 Fax: 436-7955
ASIA/PACIFIC
Hong Kong Microchip Technology Unit 3002-3004, Tower Metroplaza Hing Fong Road Kwai Fong, N.T. Hong Kong Tel: 1200 Fax: 3431 Korea Microchip Technology 168-1, Youngbo Bldg. Floor Samsung-Dong, Kangnam-Ku, Seoul, Korea Tel: 7200 Fax: 5934 Singapore Microchip Technology Middle Road #10-03 Prime Centre Singapore 188980 Tel: 8870 Fax: 8850 Taiwan Microchip Technology 10F-1C Tung North Road Taipei, Taiwan, Tel: 7175 Fax: 0139
EUROPE
United Kingdom Arizona Microchip Technology Ltd. Unit Courtyard Meadow Bank, Furlong Road Bourne End, Buckinghamshire Tel: 851077Fax:44 850259 France Arizona Microchip Technology SARL Buisson Fraises 91300 Massy France Tel: 20Fax:33 Germany Arizona Microchip Technology GmbH Gustav-Heinemann-Ring D-81739 Muenchen, Germany Tel: 0Fax:49 Italy Arizona Microchip Technology Centro Direzionale Colleoni Palazzo Pegaso Ingresso Paracelso 20041 Agrate Brianza (MI) Italy Tel: 9939 Fax: 9883
JAPAN
Microchip Technology Intl. Inc. Benex 3-18-20, Shin Yokohama Kohoku-Ku, Yokohama Kanagawa Japan Tel: 6166Fax: 6122 1/05/96
rights reserved. 1996, Microchip Technology Incorporated, USA.
*Information contained this publication regarding device applications like intended suggestion only superseded updates. representation warranty given liability assumed Microchip Technology Incorporated with respect accuracy such information, infringement patents other intellectual property rights arising from such use, otherwise. Microchip's products critical components medical devices authorized except with express written approval Microchip. licenses conveyed, implicitly otherwise, under intellectual property rights. Microchip logo name trademarks Microchip Technology Inc. rights reserved. other trademarks mentioned herein property their respective companies.
DS40134A-page
Advanced Information
1996 Microchip Technology Inc.

KEELOQ® Code Hopping Encoder Product Brief* Security Program

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