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THEORY OF OPERATION
The CMD-HHTX-XXX Remote Command Unit combines the popular Linx LC
series transmitter and “Splatch” planar antenna with a commonly available
encoder IC to form a simple yet effective RF remote control transmitter. The
product’s operation is straightforward.When a button is activated on the remote
unit, power is applied to the internal circuitry and the encoder IC is enabled.The
encoder then detects the logic states of the DIP switch address and button data
lines. These states are then formatted into a 3-word transmission cycle which
continues until the button is released.The encoder data is used to modulate the
LC transmitter which through the antenna conveys the data into free space. The
transmitted signal may be received by any Linx LC receiver or pre-made function
module. Once data is received it is decoded using a decoder IC or custom
microcontroller. The transmitted address bits are checked against the address
settings of the receiving device. If a match is confirmed, the decoder’s output(s)
are set to replicate the transmitter’s button status.
SETTING THE TRANSMITTER ADDRESS
In order to allow the formation of
up to 256 unique Transmitter-
R e c e i ver relationships, the
t ra n s m i t t e r ’s address may be
selected using internal DIP
switches as shown.The switches
are accessed by removing the
rear cover as for battery
replacement.
CONTENTION CONSIDERATIONS
It is important to understand that only one transmitter at a time can be activated
within a reception area.While the transmitted signal consists of encoded digital
data, only one carrier of any frequency can occupy airspace without contention
at any given time.
BATTERY REPLACEMENT
The remote unit utilizes a CR-2032 Button
Lithium Cell. In normal use it will provide 1-2
years of operation. Access for replacement is
accomplished by removing the screw in the
middle of the back cover. Once the unit is open,
remove the battery by depressing the release
finger on the battery holder as shown. Replace
the cell with the same type while observing the
polarity shown.
Battery Release
+
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