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Table Of Contents

 1999 Microchip Technology Inc. Preliminary DS21137E-page 1

FEATURES

Security

• Programmable 28-bit serial number

• Programmable 64-bit encryption key

• Each transmission is unique

• 66-bit transmission code length

• 32-bit hopping code

• 34-bit fixed code (28-bit serial number,

4-bit button code, 2-bit status)

• Encryption keys are read protected

Operating

• 2.0—6.3V operation

• Four button inputs

• No additional circuitry required

• 15 functions available

• Selectable baud rate

• Automatic code word completion

• Battery low signal transmitted to receiver

• Non-volatile synchronization data

Other

• Easy to use programming interface

• On-chip EEPROM

• On-chip oscillator and timing components

• Button inputs have internal pulldown resistors

• Current limiting on LED

output

• Minimum component count

• Synchronous transmission mode

Typical Applications

The HCS300 is ideal for Remote Keyless Entry (RKE)

applications. These applications include:

• Automotive RKE systems

• Automotive alarm systems

• Automotive immobilizers

• Gate and garage door openers

• Identity tokens

• Burglar alarm systems

DESCRIPTION

The HCS300 from Microchip Technology Inc., is a code

hopping encoder designed for secure Remote Keyless

Entry (RKE) systems. The HCS300 utilizes the

code

hopping technology, which incorporates high security, a

small package outline and low cost to make this device

a perfect solution for unidirectional remote keyless

entry systems and access control systems.

PACKAGE TYPES

HCS300 BLOCK DIAGRAM

VDD

LED

PWM

PDIP, SOIC

HCS300

VSS

VDD

Oscillator

Reset circuit

LED

driver

Controller

Power

latching

and

switching

Button input port

32-bit shift register

Encoder

EEPROM

PWM

LED

KEELOQ

Code Hopping Encoder

HCS300

KEELOQ is a registered trademark of Microchip Technology, Inc.

Microchip’s Secure Data Products are covered by some or all of the following patents:

Code hopping encoder patents issued in Europe, U.S.A., and R.S.A. — U.S.A.: 5,517,187; Europe: 0459781; R.S.A.: ZA93/4726

21137e.Book Page 1 Monday, October 4, 1999 8:04 AM

Summary of content (24 pages)

PAGE 1
21137e.Book Page 1 Monday, October 4, 1999 8:04 AM HCS300 KEELOQ® Code Hopping Encoder FEATURES DESCRIPTION Security The HCS300 from Microchip Technology Inc., is a code hopping encoder designed for secure Remote Keyless Entry (RKE) systems. The HCS300 utilizes the ® code hopping technology, which incorporates high security, a small package outline and low cost to make this device a perfect solution for unidirectional remote keyless entry systems and access control systems.
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1137e.Book Page 2 Monday, October 4, 1999 8:04 AM HCS300 The HCS300 combines a 32-bit hopping code generated by a non-linear encryption algorithm, with a 28-bit serial number and six status bits to create a 66bit transmission stream. The length of the transmission eliminates the threat of code scanning and the code hopping mechanism makes each transmission unique, thus rendering code capture and resend (code grabbing) schemes useless.
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21137e.Book Page 3 Monday, October 4, 1999 8:04 AM HCS300 FIGURE 1-1: CREATION AND STORAGE OF ENCRYPTION KEY DURING PRODUCTION HCS300 EEPROM Array Transmitter Serial Number or Seed Manufacturer’s Code Key Generation Algorithm Encryption Key The 16-bit synchronization value is the basis for the transmitted code changing for each transmission, and is updated each time a button is pressed.
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21137e.
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21137e.Book Page 5 Monday, October 4, 1999 8:04 AM HCS300 2.0 DEVICE OPERATION TABLE 2-1: As shown in the typical application circuits (Figure 2-1), the HCS300 is a simple device to use. It requires only the addition of buttons and RF circuitry for use as the transmitter in your security application. A description of each pin is described in Table 2-1.
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21137e.Book Page 6 Monday, October 4, 1999 8:04 AM HCS300 3.0 FIGURE 2-2: ENCODER OPERATION EEPROM MEMORY ORGANIZATION Power Up (A button has been pressed) Reset and Debounce Delay (10 ms) Sample Inputs The HCS300 contains 192 bits (12 x 16-bit words) of EEPROM memory (Table 3-1). This EEPROM array is used to store the encryption key information, synchronization value, etc. Further descriptions of the memory array is given in the following sections.
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21137e.Book Page 7 Monday, October 4, 1999 8:04 AM HCS300 3.2 SYNC (Synchronization Counter) 3.6 This is the 16-bit synchronization value that is used to create the hopping code for transmission. This value will be changed after every transmission. 3.3 SER_0, SER_1 (Encoder Serial Number) SER_0 and SER_1 are the lower and upper words of the device serial number, respectively. Although there are 32 bits allocated for the serial number, only the lower order 28 bits are transmitted.
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21137e.Book Page 8 Monday, October 4, 1999 8:04 AM HCS300 0x0000 and clear OVR1 the second time the counter wraps. Once cleared, OVR0 and OVR1 cannot be set again, thereby creating a permanent record of the counter overflow. This prevents fast cycling of 64K counter. If the decoder system is programmed to track the overflow bits, then the effective number of unique synchronization values can be extended to 196,608. If programmed to zero, the system will be compatible with the NTQ104/5/6 devices (i.e.
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21137e.Book Page 9 Monday, October 4, 1999 8:04 AM HCS300 chronous transmission mode S2 or S3 should not be toggled until all internal processing has been completed as shown in Figure 4-4. 4.3 Code Word Organization The HCS300 transmits a 66-bit code word when a button is pressed. The 66-bit word is constructed from a Fixed Code portion and an Encrypted Code portion (Figure 4-2).
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21137e.Book Page 10 Monday, October 4, 1999 8:04 AM HCS300 FIGURE 4-3: SYNCHRONOUS TRANSMISSION MODE t = 50 ms PWM S2(S3) “01,10,11” S[1:0] FIGURE 4-4: TRANSMISSION WORD FORMAT DURING SYNCHRONOUS TRANSMISSION MODE Reserved Padding Button Code Serial Number Data Word Sync Counter 16 2 4 28 16 16 Transmission Direction 5.0 SPECIAL FEATURES 5.
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21137e.Book Page 11 Monday, October 4, 1999 8:04 AM HCS300 5.5 button inputs are pressed at the same time (Table 5-1). Instead of the normal key generation method being used to create the encryption key, this seed value is used and there need not be any mathematical relationship between serial numbers and seeds. TABLE 5-1: The Auto-shutoff function automatically stops the device from transmitting if a button inadvertently gets pressed for a long period of time.
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21137e.Book Page 12 Monday, October 4, 1999 8:04 AM HCS300 5.6 VLOW: Voltage LOW Indicator The VLOW bit is transmitted with every transmission (Figure 8-4) and will be transmitted as a one if the operating voltage has dropped below the low voltage trip point. The trip point is selectable between two values, based on the battery voltage being used. See Section 3.6.5 for a description of how the low voltage select option is set.
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21137e.Book Page 13 Monday, October 4, 1999 8:04 AM HCS300 6.0 PROGRAMMING THE HCS300 as the data in line. After each 16-bit word is loaded, a programming delay is required for the internal program cycle to complete. This delay can take up to TWC. At the end of the programming cycle, the device can be verified (Figure 6-2) by reading back the EEPROM. Reading is done by clocking the S3 line and reading the data bits on PWM.
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21137e.Book Page 14 Monday, October 4, 1999 8:04 AM HCS300 TABLE 6-1: PROGRAMMING/VERIFY TIMING REQUIREMENTS VDD = 5.0V ± 10% 25° C ± 5 °C Symbol Min. Max. Program mode setup time Parameter TPS 3.5 4.5 Units ms Hold time 1 TPH1 3.5 — ms Hold time 2 TPH2 50 — µs Bulk Write time TPBW — 2.2 ms Program delay time TPROG — 2.
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21137e.Book Page 15 Monday, October 4, 1999 8:04 AM HCS300 7.0 INTEGRATING THE HCS300 INTO A SYSTEM FIGURE 7-1: TYPICAL LEARN SEQUENCE Use of the HCS300 in a system requires a compatible decoder. This decoder is typically a microcontroller with compatible firmware. Microchip will provide (via a license agreement) firmware routines that accept transmissions from the HCS300 and decrypt the hopping code portion of the data stream.
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21137e.Book Page 16 Monday, October 4, 1999 8:04 AM HCS300 7.2 Decoder Operation 7.3 In a typical decoder operation (Figure 7-2), the key generation on the decoder side is done by taking the serial number from a transmission and combining that with the manufacturer’s code to create the same secret key that was used by the transmitter. Once the secret key is obtained, the rest of the transmission can be decrypted.
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21137e.Book Page 17 Monday, October 4, 1999 8:04 AM HCS300 8.0 ELECTRICAL CHARACTERISTICS TABLE 8-1: ABSOLUTE MAXIMUM RATINGS Symbol Item VDD VIN Note: Rating Units Supply voltage -0.3 to 6.6 V Input voltage -0.3 to VDD + 0.3 V VOUT Output voltage -0.3 to VDD + 0.
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21137e.Book Page 18 Monday, October 4, 1999 8:04 AM HCS300 FIGURE 8-1: POWER UP AND TRANSMIT TIMING Button Press Detect Code Word Transmission TBP TTD TDB Code Word 1 PWM Code Word n Code Word 3 Code Word 2 TTO Sn TABLE 8-3: POWER UP AND TRANSMIT TIMING REQUIREMENTS VDD = +2.0 to 6.3V Commercial (C): Tamb = 0°C to +70°C Industrial (I): Tamb = -40°C to +85°C Parameter Symbol Min. Max.
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21137e.Book Page 19 Monday, October 4, 1999 8:04 AM HCS300 FIGURE 8-4: DATA WORD FORMAT Serial Number LSB MSB LSB Bit 0 Bit 1 Header MSB S3 S0 S1 Status S2 VLOW RPT Bit 30 Bit 31 Bit 32 Bit 33 Bit 58 Bit 59 Bit 60 Bit 61 Bit 62 Bit 63 Bit 64 Bit 65 Guard Time Fixed Code Word Hopping Code Word TABLE 8-4: CODE WORD TRANSMISSION TIMING REQUIREMENTS VDD = +2.0 to 6.
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21137e.Book Page 20 Monday, October 4, 1999 8:04 AM HCS300 HCS300 PRODUCT IDENTIFICATION SYSTEM To order or obtain information, e.g., on pricing or delivery, refer to the factory or the listed sales office.
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137e.Book Page 21 Monday, October 4, 1999 8:04 AM HCS300 NOTES:  1999 Microchip Technology Inc.
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21137e.Book Page 22 Monday, October 4, 1999 8:04 AM HCS300 NOTES: DS21137E-page 22 Preliminary  1999 Microchip Technology Inc.
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21137e.Book Page 23 Monday, October 4, 1999 8:04 AM HCS300 NOTES:  1999 Microchip Technology Inc.
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WORLDWIDE SALES AND SERVICE AMERICAS AMERICAS (continued) Corporate Office Toronto Singapore Microchip Technology Inc. 2355 West Chandler Blvd. Chandler, AZ 85224-6199 Tel: 480-786-7200 Fax: 480-786-7277 Technical Support: 480-786-7627 Web Address: http://www.microchip.com Microchip Technology Inc. 5925 Airport Road, Suite 200 Mississauga, Ontario L4V 1W1, Canada Tel: 905-405-6279 Fax: 905-405-6253 Microchip Technology Singapore Pte Ltd.