HCS410-IP Microchip Technology, HCS410-IP Datasheet - Page 8

• Manufacturer Part Number: HCS410-IP
• Description: KEELOQ CODE HOPPING ENCODER AND TRANSPONDER
• Manufacturer: Microchip Technology

HCS410
2.2
The HCS410 wakes up upon detecting a switch closure
and then delays approximately 30 ms for switch
debounce (Figure 2-7). The synchronization counter
value, fixed information, and switch information are
encrypted to form the code hopping portion. The
encrypted or code hopping portion of the transmission
changes every time a button is pressed, even if the
same button is pushed again. Keeping a button
pressed for a long time results in the same code word
being transmitted until the button is released or time-
out occurs. A code that has been transmitted will not
occur again for more than 64K transmissions. Overflow
information programmed into the encoder can be used
by the decoder to extend the number of unique trans-
missions to more than 192k.
FIGURE 2-7:
DS40158C-page 8
Yes
Code Hopping Mode (CH Mode)
No
(A button has been
Update Sync Info
pressed (Note1)
Buttons added?
Sample Inputs
Encrypt With
Encoder Key
All buttons
20-second
released?
Power-up
Transmit
(Note 1)
timeout
CODE HOPPING ENCODER OPERATION
No
No
Yes
Yes
Note 1: 30 ms debounce on press and release of all buttons.
DINC
Set?
No
2: Completes a minimum of 3 code words if MTX3 is set.
Preliminary
Yes
No
Complete current
checking buttons
code word while
Increase sync
completed?
20 second
(Note 2)
pressed?
Buttons
(Note 1)
time-out
counter
If, during the transmit process, it is detected that a new
button(s) has been added, a reset will immediately be
forced and the code word will not be completed. Please
note that buttons removed will not have any effect on
the code word unless no buttons remain pressed in
which case the current code word will be completed
and the power down will occur. If, after a button combi-
nation is pressed, and the same button combination is
pressed again within 2 seconds of the first press, the
current transmission will be aborted and a new trans-
mission will start with the queue counter (QUE)
incremented.
No
by 12
Yes
Yes
No
Yes
7 complete code
Transmitted
completed?
DINC Set?
Power down
Yes
2 second
words?
time-out
No
1997 Microchip Technology Inc.
Yes
No
No
Stop transmitting
immediately
Increment queue
Same as
pressed?
previous
Buttons
(Note 1)
counter
press?
No
Yes
Yes