User's Manual

Page 3
SETTING THE TRANSMITTER ADDRESS
The Compact Hand Held transmitter
allows the selection of one of 1024
unique addresses. All transmitters are
supplied set to the same address. To
avoid contention with other units or to
create unique relationships, the address
can be changed. This is accomplished
using internal DIP switches as shown.
The switches are accessed by removing
the DIP switch access cover on the back
of the transmitter.
If the switch is on, the address line is
connected to ground, otherwise it is floating. The receiver's address must match
exactly in order for the units to communicate. Application Note AN00300
describes in detail how to set the address to match any of the receivers offered
by Linx. This note can be found in the Support section of the Linx web site,
www.linxtechnologies.com.
CMD-HHCP BUTTON ASSIGNMENTS
This diagram illustrates the relationship between the button locations and
encoder/decoder data lines.
D7 D6
D5 D4
D3 D2
D1 D0
Page 2
OFF ON
A0 = 1
A1 = 2
A2 = 3
A3 = 4
A4 = 5
A5 = 6
A6 = 7
A7 = 8
A8 = 9
A9 = 10
Figure 2: DIP Switch Assignments
Figure 3: CMD-HHCP-xxx Button Assignments
ELECTRICAL SPECIFICATIONS
PPaarraammeetteerr DDeessiiggnnaattiioonn MMiinn.. TTyyppiiccaall MMaaxx.. UUnniittss NNootteess
POWER SUPPLY
Operating Voltage V
CC
2.1 3.0 3.6 V
DC
–
Supply Current I
CC
–
3.4
–
mA
–
Power-down Current I
PDN
–
50
–
nA
1
TRANSMITTER SECTION
Transmit Frequency Range F
C
CMD-HHLR-315
–
315
–
MHz
–
CMD-HHLR-418
–
418
–
MHz
–
CMD-HHLR-433
– 433.92 –
MHz
–
Center Frequency Accuracy
–
-50
–
+50 kHz
–
ENVIRONMENTAL
Operating Temperature Range – -40 – +85
°C1
1. Characterized, but not tested.
Notes
THEORY OF OPERATION
The CMD-HHCP-xxx Remote Command Unit combines the LR Series
transmitter with an internal Splatch Series antenna with an on-board Holtek
HT640 encoder IC to form a simple, yet highly reliable, RF remote-control
transmitter. The LR transmitter is a low-cost, high-performance synthesized
ASK/OOK transmitter. The transmitter’s synthesized architecture delivers
outstanding stability and frequency accuracy while minimizing the effects of
antenna port loading and mismatching. This reduces or eliminates frequency
pulling, bit contraction, and other negative effects that are common to SAW-
based transmitter architectures, providing a significantly higher level of
performance and reliability.
When a button is pressed 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 address lines and button data lines. These states are formatted into a
three-word transmission cycle that continues until the button is released. The
encoder data is used to modulate the transmitter, which, through the antenna,
conveys the data into free space. On the receiver side, a decoder IC or custom
microcontroller is used to check the transmitter's address bits against the
address settings of the receiving device. If a match is confirmed, the decoder’s
outputs are set to replicate the transmitter’s button states. These outputs can
then be used to activate external circuitry required by the application.
The transmitter is compatible with several Linx receiver products, including the
LC, LR, KH, and OEM product families. For applications where range is critical,
the LR Series receiver is the best choice due to its outstanding sensitivity. When
the transmitter is combined with an LR Series receiver and the HT658 decoder
chip, ranges up to 1000 feet are possible. Applications operating over shorter
distances will also benefit from the increased link reliability and superior noise
immunity provided by the LR Series receiver.