HCS410_11 Datasheet, PDF (12/46 Pages) Microchip Technology – KEELOQ® Code Hopping Encoder and Transponder 2-bit CRC, 2-bit queue

HCS410
2.3.9 LED OUTPUT
The S2/LED line can be used to drive a LED when the
HCS410 is transmitting. If this option is enabled in the
configuration word the S2 line is driven high periodi-
cally when the HCS410 is transmitting as shown in
Figure 2-14. The LED output operates with a 30 ms on
and 480 ms off duty cycle when the supply voltage is
above the level indicated by the VLOW bit in the config-
uration word. When the supply voltage drops below the
voltage indicated by the VLOW bit the HCS410 will indi-
cate this by turning the LED on for 200ms at the start of
a transmission and remain off for the rest of the trans-
mission.
2.3.10 DELAYED INCREMENT
The HCS410 has a delayed increment feature that
increments the counter by 12, 20 seconds after the last
button press occurred. The 20-second time-out is reset
and the queue counter will increment if another press
occurs before the 20 seconds expires. The queue
counter is cleared after the buttons have been released
for more than 2 seconds. Systems that use this feature
will circumvent the latest jamming-code grabbing
attackers.
2.3.11 OTHER CONFIGURABLE OPTIONS
Other configurable code hopping options include an
• Transmission-rate selection
• Extended serial number.
These are described in more detail in Section 3.7.
FIGURE 2-14: LED INDICATION DURING TRANSMISSION
S Input
LED
VDD = VLOW Level
LED
VDD < VLOW LEVEL
200 ms
200 ms
480 ms
30 ms
DS40158F-page 12
© 2011 Microchip Technology Inc.