RFHCS362G_11 Datasheet, PDF (17/54 Pages) Microchip Technology – KEELOQ® Code Hopping Encoder with UHF ASK/FSK Transmitter

3.2 LED Output
The LED pin will be driven LOW periodically while the
rfHCS362 is transmitting data to power an external
LED.
The duty cycle (TLEDON/TLEDOFF) can be selected
between two possible values by the configuration
option (LED).
FIGURE 3-7: LED OPERATION (LED = 1)
S[3210]
VDD > VLOW
LED
TLEDON TLEDOFF
TLEDON = 25 ms _{TLEDOFF = 500 ms}
VDD < VLOW
LED
The same configuration option determines whether
when the VDD Voltage drops below the selected VLOW
trip point the LED will blink only once or stop blinking.
FIGURE 3-8: LED OPERATION (LED = 0)
S[3210]
VDD > VLOW
TLEDON
TLEDOFF
LED
TLEDON = 200 ms
VDD < VLOW
TLEDOFF = 800 ms
LED
rfHCS362G/362F
3.3 Dual Encoder Operation
The rfHCS362G/362F contains two encryption keys
(for example derived from two different Manufacturer’s
Codes), but only one Serial Number, one set of Dis-
crimination bits, one 16-bit Synchronization Counter
and a single 60-bit Seed value. For this reason the
rfHCS362G/362F can be used as an encoder in multi-
ple (two) applications as far as they share the same
configuration: transmission format, baud rate, header
and guard settings. The SHIFT input pin (multiplexed
with the LED output) is used to select between the two
encryption keys.
A logic 1 on the SHIFT input pin selects the first encryp-
tion key.
A logic 0 on the SHIFT input pin will select the second
encryption key.
FIGURE 3-9: USING DUAL ENCODER
OPERATION
VDD
VDD
LED/SHIFT
DATA
VSS
1 kΩ
SHIFT
Note:
When the rfHCS362 encoder is used
as a Dual Encoder the LED pin is used
as a SHIFT input (Figure 3-9). In such
a configuration the LED is always ON
during transmission. To keep power
consumption low, it is recommended
to use a series resistor of relatively
high value. VLOW information is not
available when using the second
Encryption Key.
© 2011 Microchip Technology Inc.
DS41189B-page 17