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PDF HCS515 Data sheet ( Hoja de datos )
| Número de pieza | HCS515 | |
| Descripción | KEELOQ CODE HOPPING DECODER | |
| Fabricantes | Microchip Technology | |
| Logotipo |  |
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M
HCS515
Code Hopping Decoder
FEATURES
Security
• Encrypted storage of manufacturer’s code
• Encrypted storage of encoder decryption keys
• Up to seven transmitters can be learned
• KEELOQ code hopping technology
• Normal and secure learning mechanisms
Operating
• 3.0V—5.5V operation
• Internal oscillator
• Auto bit rate detection
Other
• Stand-alone decoder
• Internal EEPROM for transmitter storage
• Synchronous serial interface
• 1 Kbit user EEPROM
• 14-pin DIP/SOIC package
Typical Applications
• Automotive remote entry systems
• Automotive alarm systems
• Automotive immobilizers
• Gate and garage openers
• Electronic door locks
• Identity tokens
• Burglar alarm systems
Compatible Encoders
• HCS200, HCS300, HCS301, HCS360, HCS361,
HCS410 (PWM Mode)
DESCRIPTION
The Microchip Technology Inc. HCS515 is a code hop-
ping decoder designed for secure Remote Keyless
Entry (RKE) systems. The HCS515 utilizes the pat-
ented KEELOQ code hopping system and high security
learning mechanisms to make this a canned solution
when used with the HCS encoders to implement a uni-
directional remote and access control systems. The
HCS515 can be used as a stand-alone decoder or in
conjunction with a microcontroller.
PACKAGE TYPE
PDIP, SOIC
NC
NC
Vdd
S0
S1
MCLR
NC
1
2
3
4
5
6
7
14 NC
13 NC
12 Vss
11 RF_IN
10 S_CLK
9 S_DAT
8 NC
BLOCK DIAGRAM
RFIN
67-bit Reception Register
Internal
EEPROM
EE_DAT
EE_CLK
CONTROL
OSCILLATOR
DECRYPTOR
S_DAT
S_CLK
S0
S1
MCLR
The manufacturer’s code, encoder decryption keys,
and synchronization information are stored in
encrypted form in internal EEPROM. The HCS515
uses the S_DAT and S_CLK inputs to communicate
with a host controller device.
The HCS515 operates over a wide voltage range of
3.0 volts to 5.5 volts. The decoder employs automatic
bit-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.
The KEELOQ name, KEELOQ logo, and logotype are registered trademarks of Microchip Technology Inc. in the U.S.A. and other countries.
*Code hopping patents issued in Europe, U. S. A. and R. S.—US:5,517,187; Europe: 0459781
© 1998 Microchip Technology Inc.
Preliminary
DS40183A-page 1
1 page  
3.0 DECODER OPERATION
3.1 Learning a Transmitter to a Receiver
(Normal or Secure Learn)
Before the transmitter and receiver can work together,
the receiver must first ‘learn’ and store the following
information from the transmitter in EEPROM:
• A check value of the serial number
• The encoder decryption key
• The current synchronization counter value
The decoder must also store the manufacturer’s code
(Section 1.2) in protected memory. This code will
typically be the same for all of the decoders in a sys-
tem.
The HCS515 has seven memory slots, and, conse-
quently, can store up to seven transmitters. During the
learn procedure, the decoder searches for an empty
memory slot for storing the transmitter’s information.
When all of the memory slots are full, the decoder will
overwrite the last transmitter’s information. To erase all
of the memory slots at once, use the ERASE_ALL
command (C3H).
3.1.1 LEARNING PROCEDURE
Learning is initiated by sending the ACTIVATE_LEARN
(D2H) command to the decoder. The decoder acknowl-
edges reception of the command by pulling the data
line high.
For the HCS515 decoder to learn a new transmitter, the
following sequence is required:
1. Activate the transmitter once.
2. Activate the transmitter a second time. (In
secure learning mode, the seed transmission
must be transmitted during the second stage of
learn by activating the appropriate buttons on
the transmitter.)
The HCS515 will transmit a learn-status string,
indicating that the learn was successful.
3. The decoder has now learned the transmitter.
4. Repeat steps 1-3 to learn up to seven
transmitters
Note 1: Learning will be terminated if two
nonsequential codes were received or if two
acceptable codes were not decoded within
30 seconds.
2: If more than seven transmitters are learned,
the new transmitter will replace the last
transmitter learned. It is, therefore, not pos-
sible to erase lost transmitters by
repeatedly learning new transmitters. To
remove lost or stolen transmitters,
ERASE_ALL transmitters and relearn all
available transmitters.
HCS515
3: Learning a transmitter with an encoder
decryption key that is identical to a transmit-
ter already in memory replaces the existing
transmitter. In practice, this means that all
transmitters should have unique encoder
decryption keys. Learning a previously
learned transmitter does not use any addi-
tional memory slots.
The following checks are performed by the decoder to
determine if the transmission is valid during learn:
• The first code word is checked for bit integrity.
• The second code word is checked for bit integrity.
• The encoder decryption key is generated accord-
ing to the selected algorithm.
• The hopping code is decrypted.
• The discrimination value is checked.
• If all the checks pass, the key, serial number
check value, and synchronization counter values
are stored in EEPROM memory.
Figure 3-1 shows a flow chart of the learn sequence.
FIGURE 3-1: LEARN SEQUENCE
Enter Learn
Mode
Wait for Reception
of a Valid Code
Wait for Reception
of Second
Non-Repeated
Valid Code
Generate Key
from Serial Number/
Seed Value
Use Generated Key
to Decrypt
Compare Discrimination
Value with Serial Number
Equal? No
Yes
Learn successful. Store:
Serial number check value
Encoder decryption key
Sync. counter value
Learn
Unsuccessful
Exit
© 1998 Microchip Technology Inc.
Preliminary
DS40183A-page 5
5 Page 
HCS515
4.2.8 ACTIVATE LEARN
The activate learn command (Figure 4-7) is used to
activate a transmitter learning sequence on the
decoder. The command consists of a command mode
activation sequence, a command byte, and two dummy
bytes. The decoder will respond by taking the data line
high to acknowledge that the command was valid and
that learn is active.
Upon reception of the first transmission, the decoder
will respond with a learn status message (Figure 4-8).
During learn, the decoder will acknowledge the recep-
tion of the first transmission by taking the data line high
for 60 ms. The controlling microcontroller can clock out
at most eight bits, which will all be zeros. All of the bits
of the status byte are zero, and this is used to distin-
guish between a learn time-out status string and the
first transmission received string. The controlling micro-
controller must ensure that the clock line does not go
high 60 ms after the falling edge of the data line, for this
will terminate learn.
FIGURE 4-7: LEARN MODE ACTIVATION
CLK
µC DATA
LSB MSB LSB
Upon reception of the second transmission, the
decoder will respond with a learn status message
(Figure 4-9).
The learn status message after the second transmis-
sion consists of the following:
• 1 start bit.
• The function code [S3:S0] of the message is zero,
indicating that this is a status string.
• The RESULT bit indicates the result of the learn
sequence. The RESULT bit is set if successful
and cleared otherwise.
• The OVR bit will indicate whether an exiting trans-
mitter is over written. The OVR bit will be set if an
existing transmitter is learned over.
• The [CNT3…CNT0] bits will indicate the number
of transmitters learned on the decoder.
• The [TX3…TX0] bits indicate the block number
used during the learning of the transmitter.
MSB LSB
TLRN
TACK
TRESP
MSB
TACK2
Decoder DATA
Start Command
AB
Command Byte
C
Dummy Byte
D
Dummy Byte
E
Acknowledge
F
FIGURE 4-8:
LEARN STATUS MESSAGE AFTER FIRST TRANSMISSION
CLK
TCLA
TCA
TCLL
TCLKL
TCLH
TCLKH
TDS
Decoder
Data
TDHI
Command Request
0
0 00 0 0 00
Status Byte
AB
C
FIGURE 4-9:
CLK
TCLA
LEARN STATUS MESSAGE AFTER SECOND TRANSMISSION
TACT
TCLL
TCLKL
TCLKH
TDS
TCLH
TDHI
Decoder
Data
0 OVR RSLT 0
Communications Request
0 0 0 1 CNT0
Learn Status Bits
CNT3 TX0
TX3 RX0 RX1
RX62 RX63
Decoded Tx
AB
Ci Cii
© 1998 Microchip Technology Inc.
Preliminary
DS40183A-page 11
11 Page | ||
| Páginas | Total 28 Páginas | |
| PDF Descargar | [ Datasheet HCS515.PDF ] | |
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