LICAL-DEC-HS001 Linx Technologies Inc, LICAL-DEC-HS001 Datasheet - Page 6

• Manufacturer Part Number: LICAL-DEC-HS001
• Description: IC DECODER HS SERIES 20-SSOP
• Manufacturer: Linx Technologies Inc
• Series: HSr
• Type: Decoderr

Specifications of LICAL-DEC-HS001

• Package / Case: 20-SSOP
• Applications: RF, IR
• Mounting Type: Surface Mount
• Supply Voltage (max): 5.5 V
• Supply Voltage (min): 2 V
• Maximum Operating Temperature: + 125 C
• Minimum Operating Temperature: - 40 C
• Mounting Style: SMD/SMT
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant, Lead free / RoHS Compliant

DECODER POWER-UP
DECODER RECEIVE MODE
DECODER CREATE KEY MODE
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When the decoder first powers up, it will set the baud rate and go to sleep until:
1) the LEARN line is taken high, placing the decoder into Learn Mode, 2) a rising
edge (low to high transition) on the COPY_IN line puts it into Get Copy Mode, or
3) a rising edge on the DATA_IN line puts it into Receive Mode.
When a rising edge is seen on the DATA_IN line, the decoder enters Receive
Mode. It will begin by looking for a valid packet (meaning one that can be
decrypted with the saved key) that has no errors. If the packet is valid, then the
decoder will replicate the Data byte on its data lines and pull the MODE_IND line
high. It will also output a number that represents the ID of the encoder. It will
output this number once when the first valid packet is received. The decoder will
then look for the next valid packet. If an error is detected at any time, or if the
transmission cannot be decrypted with the saved key, then the decoder will
ignore the packet and look for the next one.
If no valid packet is detected within 262mS, the decoder will go back to sleep.
Create Key Mode is entered when the LEARN and CREATE_KEY lines on the
decoder are taken high at the same time. When this happens, the MODE_IND
line will go high as an indication that the decoder is ready to create the key. The
CREATE_KEY line will need to go high ten times to set the key. Each edge on
the line starts a timer that is used to populate a part of the key. This method is
used to gather entropy so that the key will be truly random and will choose from
among all 2
Following the tenth press, the decoder will begin to send the key to the encoder
on the KEY_OUT line. This will be output as a serial data stream, so it can be
sent to the encoder by any method suitable for serial data transfer. This can
include the use of a wire, contact points on an enclosure, or infrared. The HS
Series Master Development System demonstrates wire and infrared transfer
methods. You may wish to refer to the development system User’s Guide for
circuit schematics and further details.
Once the encoder receives the key on its KEY_IN line, it will send a confirmation
to the decoder through its DATA_OUT line. This means that the standard mode
of communication, whether a wire, RF, or infrared, must be active. When the
decoder receives this confirmation, it will send a final confirmation through the
KEY_OUT line. The MODE_IND LED lines on the encoder and the decoder will
turn on for one second. This indicates that the encoder and decoder are now
ready to be used. The decoder will output the key information for seventeen
seconds or until it receives a valid confirmation from the encoder. If Control
Permissions are going to be used, they may now be set as described in the
Decoder Learn Mode section.
Note that the CREATE_KEY line should be connected to a button or another
contact that will give random times between presses. Connecting this line to a
deterministic source, such as a microprocessor clock, will not produce a secure
key and could compromise the system.
80
possible keys.
DECODER LEARN MODE
Learn Mode serves several functions in the HS decoder. First, it provides the
access point for other modes, such as Send Copy, Create Key, and Clear
Memory. It also enables the decoder to learn the Control Permissions for an
encoder. One of the most innovative features of the MS and HS Series is their
ability to establish a unique user identity and profile for the device containing the
encoder. In other products, all encoded transmissions are either recognized or
denied based on the address. In cases where encoder and decoder addresses
match, the state of all data lines is recognized and output. The HS Series
uniquely allows a user or manufacturer to define which encoder inputs will be
acknowledged by each decoder.
Consider this practical example: a three door garage houses Dad’s Corvette,
Mom’s Mercedes, and Son’s Yugo. With most competitive products, any user’s
keyfob could open any garage door as long as the addresses match. In a Linx
HS-based system, the keyfobs could easily be configured to open only certain
doors (guess which one Son gets to open!)
The decoder is placed into Learn Mode by pulling the LEARN line high and then
taking it low within ten seconds. The decoder will begin toggling the MODE_IND
line to indicate that the decoder is ready to learn the Control Permissions for a
specific encoder. On the encoder end, simply activate each data line that it will
be allowed to access and the decoder will record the lines that were activated as
the Control Permissions. Pull the LEARN line high again or let the decoder time-
out after 17 seconds, after which it will automatically exit Learn Mode and return
to sleep.
The decoder can store up to 15 encoder IDs in memory. If a new encoder is
learned while the memory is full, then the decoder will wrap around and write the
new User Data over the first User Data in memory. The decoder will flash the
MODE_IND line five times as an indication that the memory is full and the next
code learned will overwrite the first. This must be clearly conveyed to the end
user, since system users’ access would be affected by the overwrites.
If the LEARN line is held high for ten seconds, the decoder will erase all of the
saved User Data from memory. The MODE_IND line will be high for as long as
the LEARN line is high, but after ten seconds, it will go low. Once the LEARN line
is pulled low again, the MODE_IND line will go high for two seconds to indicate
that the memory has been cleared.
If the LEARN line is held high at the same time as the SEND_COPY line, the
decoder will enter Send Copy Mode. Once in this mode, the state of the LEARN
line is not checked again, so it can be held high or pulled to ground, whichever
is more convenient for the application.
If the LEARN line is held high at the same time as the CREATE_KEY line, the
decoder will enter Create Key Mode.
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