HCS412_11 Datasheet, PDF (16/52 Pages) Microchip Technology – KEELOQ® Code Hopping Encoder and Transponder Burglar alarm systems

HCS412
3.4.8 QLVS FEATURES
Setting the HCS412’s special QLVS (‘Quick Secure
Learning’) configuration option enables the following
options:
• Reduces the time (TDSD) before a delayed seed
transmission begins.
• Disables DATA modulation when the LED pin is
driven low (Figure 3-11).
- If the PLL Interface option is set to ASK, the
DATA pin will go low while the LED pin is low.
- If the PLL Interface option is set to FSK, the
DATA pin will go high and the RFEN output
will go low while the LED pin is low. If the bat-
tery is low, the HCS412 transmits only until
the LED goes on.
• If the Temporary Seed (TMPSD) option is
enabled, seed transmission capability can be dis-
abled by applying the button sequence shown in
Figure 3-12
FIGURE 3-11: LED, DATA, RFEN INTERACTION WHEN QLVS IS SET
QLVS = 1, RFEN = 1
SWITCH
LED
AFSK = 0 (ASK)
S2/RFEN/LC1
TTD TLEDON
DATA
AFSK = 1 (FSK)
S2/RFEN/LC1
DATA
FIGURE 3-12: SEED DISABLE WAVEFORM
50 ms
S0, S1
50 ms
1200 ms
DS41099D-page 16
© 2011 Microchip Technology Inc.