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HCS512 Dataheets PDF



Part Number HCS512
Manufacturers Microchip Technology
Logo Microchip Technology
Description KEELOQ CODE HOPPING DECODER
Datasheet HCS512 DatasheetHCS512 Datasheet (PDF)

M FEATURES Security • • • • • Secure storage of Manufacturer’s Code Secure storage of transmitter’s keys Up to four transmitters can be learned KEELOQ code hopping technology Normal and secure learning mechanisms PDIP, SOIC LRNIN LRNOUT NC MCLR GND S0 S1 S2 S3 1 2 3 4 5 6 7 8 9 HCS512 Code Hopping Decoder PACKAGE TYPE 18 17 16 15 14 13 12 11 10 HCS512 RFIN NC OSCIN OSCOUT VDD DATA CLK SLEEP VLOW Operating • • • • • 3.0V – 6.0V operation 4 MHz RC oscillator Learning indication on LRNOUT Auto ba.

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M FEATURES Security • • • • • Secure storage of Manufacturer’s Code Secure storage of transmitter’s keys Up to four transmitters can be learned KEELOQ code hopping technology Normal and secure learning mechanisms PDIP, SOIC LRNIN LRNOUT NC MCLR GND S0 S1 S2 S3 1 2 3 4 5 6 7 8 9 HCS512 Code Hopping Decoder PACKAGE TYPE 18 17 16 15 14 13 12 11 10 HCS512 RFIN NC OSCIN OSCOUT VDD DATA CLK SLEEP VLOW Operating • • • • • 3.0V – 6.0V operation 4 MHz RC oscillator Learning indication on LRNOUT Auto baud rate detection Power saving sleep mode Other • • • • Stand alone decoder On-chip EEPROM for transmitter storage Four binary function outputs–15 functions 18-pin DIP/SOIC package BLOCK DIAGRAM RFIN 67-Bit Reception Register Typical Applications • • • • • • • Automotive remote entry systems Automotive alarm systems Automotive immobilizers Gate and garage openers Electronic door locks Identity tokens Burglar alarm systems EEPROM CONTROL DECRYPTOR DATA CLK LRNIN SEL MCLR SLEEP CONTROL S3 VLOW LRNOUT OSCIN OSCILLATOR OUTPUT S0 S1 S2 Compatible Encoders • HCS200, HCS300, HCS301, HCS360, HCS361 • NTQ106 DESCRIPTION The Microchip Technology Inc. HCS512 is a code hopping decoder designed for secure Remote Keyless Entry (RKE) systems. The HCS512 utilizes the patented KEELOQ code hopping system and high security learning mechanisms to make this a canned solution when used with the HCS encoders to implement a unidirectional remote keyless entry system. The Manufacturer’s Code, transmitter keys, and synchronization information are stored in protected on-chip EEPROM. The HCS512 uses the DATA and CLK inputs to load the Manufacturer’s Code which cannot be read out of the device. The HCS512 operates over a wide voltage range of 3.0 volts to 6.0 volts. The decoder employs automatic baud rate detection which allows it to compensate for wide variations in transmitter data rate. The decoder contains sophisticated error checking algorithms to ensure only valid codes are accepted. © 1997 Microchip Technology Inc. DS40151C-page 1 HCS512 1.0 1.1 KEELOQ SYSTEM OVERVIEW Key Terms 1.2 HCS Encoder Overview • Manufacturer’s Code – a 64-bit word, unique to each manufacturer, used to produce a unique encoder key in each transmitter (encoder). • Encoder Key – a 64-bit key, unique for each transmitter. The encoder key controls the decryption algorithm and is stored in EEPROM on the decoder device. • Learn – The receiver uses information that is transmitted to derive the transmitter’s secret key, decrypt the discrimination value and the synchronization counter in learning mode. The encoder key is a function of the Manufacturer’s Code and the device serial number and/or seed value. The HCS encoders and decoders employ the KEELOQ code hopping technology and an encryption algorithm to achieve a high level of security. Code hopping is a method by which the code transmitted from the transmitter to the receiver is different every time a button is pushed. This method, coupled with a transmission length of 66 bits, virtually eliminates the use of code ‘grabbing’ or code ‘scanning’. The HCS encoders have a small EEPROM array which must be loaded with several parameters before use. The most important of these values are: • A 28-bit serial number which is meant to be unique for every encoder • An encoder key that is generated at the time of production • A 16-bit synchronization value The serial number for each encoder is programmed by the manufacturer at the time of production. The generation of the encoder key is done using a key generation algorithm (Figure 1-1). Typically, inputs to the key generation algorithm are the serial number of the encoder and a 64-bit manufacturer’s code. The manufacturer’s code is chosen by the system manufacturer and must be carefully controlled. The manufacturer’s code is a pivotal part of the overall system security. FIGURE 1-1: CREATION AND STORAGE OF ENCODER KEY DURING PRODUCTION Transmitter Serial Number or Seed HCSXXX EEPROM Array Serial Number Encoder Key Sync Counter Manufacturer’s Code Key Generation Algorithm Encoder Key . . . DS40151C-page 2 © 1997 Microchip Technology Inc. HCS512 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. Because of the complexity of the code hopping encryption algorithm, a change in one bit of the synchronization value will result in a large change in the actual transmitted code. There is a relationship (Figure 1-3) between the key values in EEPROM and how they are used in the encoder. Once the encoder detects that a button has been pressed, the encoder reads the button and updates the synchronization counter. The synchronization value is then combined with the encoder key in the encryption algorithm, and the output is 32 bits of encrypted information. This data will change with every button press, hence, it is referred to as the hopping portion of the code word. The 32-.


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