hcs362 Microchip Technology Inc., hcs362 Datasheet - Page 8

• Manufacturer Part Number: hcs362
• Description: Keeloq Code Hopping Encoder
• Manufacturer: Microchip Technology Inc.

HCS362
3.0
The HCS362 will wake-up upon detecting a switch clo-
sure and then delay for switch debounce (Figure 3-1).
The synchronization information, fixed information and
switch information will be encrypted to form the hop-
ping code. The encrypted or hopping code portion of
the transmission will change every time a button is
pressed, even if the same button is pushed again.
Keeping a button pressed for a long time will result in
the same code word being transmitted until the button
is released or time-out occurs.
The time-out time can be selected with the Time-out
(
allows the time-out to be disabled or set to 0.8 s, 3.2 s
or 25.6 s. When a time-out occurs, the device will go
into SLEEP mode to protect the battery from draining
when a button gets stuck.
If in the transmit process, it is detected that a new but-
ton is pressed, the current code word will be aborted. A
new code word will be transmitted and the time-out
counter will RESET. If all the buttons are released, the
minimum code words will be completed. The minimum
code words can be set to 1,2,4 or 8 using the Minimum
Code Words (
time for transmitting the minimum code words is longer
than the time-out time, the device will not complete the
minimum code words.
A code that has been transmitted will not occur again
for more than 64K transmissions. This will provide
more than 18 years of typical use before a code is
repeated based on 10 operations per day. Overflow
information programmed into the encoder can be used
by the decoder to extend the number of unique trans-
missions to more than 192K.
DS40189D-page 8
TIMOUT
Note:
DEVICE OPERATION
[
0..1
Buttons removed will not have any
effect on the code word unless no but-
tons remain pressed in which case the
current code word will be completed
and the power-down will occur.
MTX
]) configuration option. This option
[
0..1
]) configuration option. If the
Preliminary
FIGURE 3-1:
No
No
No
Sample Buttons
Get Config.
Increment
Time-out
Counter
Transmit
Buttons
Encrypt
Buttons
START
Seed
Time
Seed
MTX
BASIC FLOW DIAGRAM OF
THE DEVICE OPERATION
TX?
New
No
No
Yes
No
No
Yes
No
2002 Microchip Technology Inc.
Yes
Yes
Yes
Yes
STOP
Button
Seed
Seed
No
Read
Yes