LICAL-TRC-MT Linx Technologies Inc, LICAL-TRC-MT Datasheet - Page 4

• Manufacturer Part Number: LICAL-TRC-MT
• Description: IC TRANSCODER MT BI-DIR 20-SSOP
• Manufacturer: Linx Technologies Inc
• Series: MTr
• Type: Transcoderr

Specifications of LICAL-TRC-MT

• Package / Case: 20-SSOP
• Applications: RF, IR
• Mounting Type: Surface Mount
• Supply Voltage (max): 5.5 V
• Supply Voltage (min): 2 V
• Maximum Operating Temperature: + 85 C
• Minimum Operating Temperature: - 40 C
• Mounting Style: SMD/SMT
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant, Lead free / RoHS Compliant
• Other names: LICAL-TRC-MTTR

OVERVIEW
Page 6
Many products and applications call for the transfer of button presses or switch
closures across a wireless link. Traditionally, a remote control link has operated
in only one direction, from a transmitter to a receiver. The cost associated with
transceivers has been too high to practically implement in low-cost products.
With the increasing availability of low-cost transceiver solutions, bi-directional
links are now practical and open a new world of opportunity.
In a wireless environment, maintaining the reliability and uniqueness of a
transmitted signal is generally of great importance. In a unidirectional system, IC
devices called encoders and decoders are often utilized to simplify this process.
The encoder side turns the status of a number of input lines into an encoded
serial bit-stream output intended for transmission via an RF or infrared link. Once
received, the decoder decodes, error checks, and analyzes the transmission. If
the transmission is authenticated, the decoder’s output lines are set to replicate
the status of the encoder’s input lines.
To accommodate bi-directional links, a new type of device has been developed.
Called a transcoder, this device combines a remote control encoder and decoder
into a single device, and is capable of sending commands as well as receiving
them. It is also able to receive an automatic confirmation from the remote side
indicating that its command was received and the appropriate action was taken.
For example, verifying that an automobile’s doors are all closed and have locked,
or a remote valve has actually closed.
The Linx MT Series is a revolutionary transcoder product designed for wireless
remote control applications. The same device can be used as an encoder,
decoder, or transcoder and is ideal for both uni- and bidirectional applications
and even mixtures of the two. The MT Series is easily implemented, making it
ideal for even the most basic applications, but its rich feature set also allows it to
meet the needs of far more complex applications. These features include the
ability to identify the originating transmitter, establish user permissions, select
output latch modes on a “per pin” basis, and a powerful serial interface that
allows control and information exchange with external microcontrollers or a PC.
Consider a brief example of how just one of the MT’s innovative features could
be used to transform a relatively simple application, the common garage door
opener. In competitive devices, encoded transmissions are generally either
recognized or denied based on the address. If the addresses match, the state of
all data lines will be recognized and output. The MT Series allows a user or
manufacturer to establish a user identity and profile that determines which inputs
will be acknowledged. Let’s apply this capability practically to our example: a
three door garage houses Dad’s Corvette, Mom’s Mercedes, and Son’s Yugo.
With most competitive products, any user’s keyfob could open any garage door
as long as the addresses match. In a Linx MT-based system, each individual
keyfob could easily be configured to open only certain doors (guess which one
Son gets to open!)
As you review this data guide keep in mind that it seeks to cover the full scope
of the MT’s capabilities. The implementation for a simple one button remote will
be different than a powerful targeted control, command, or status network. While
it is unlikely that all of the features of this part will be utilized at any one time, their
availability provides great design flexibility and opens up many new opportunities
for product innovation.
TRANSCEIVER POWER CONTROL
OPERATION WITH THE MS SERIES
• More users (60 vs. 40)
• Automatic confirmation
• The lower duty cycle (25% vs. 50%) of the MT Series allows for greater range
• The serial output on every packet instead of just once per receive session.
• Allows existing receive stations using the MS Series decoder to be upgraded to
• Mixed MS / MT-based systems that allow cost savings for units that only require
The transcoder has the option to control power to an external transceiver through
the TR_PDN line. This line can be connected to a power down or supply line of
a Linx transceiver or a similar input on another transceiver. This allows the
transcoder to power down the transceiver when it is not required, thereby
reducing current consumption and prolonging battery life.
The transcoder pulls the TR_SEL line low to place the transceiver into receive
mode and looks for valid data for 16mS or 32mS, depending on the baud rate. If
data is present on the TR_DATA line, then the transcoder enters Receive Mode.
If no data is present, then the transcoder pulls the TR_PDN line low to power
down the transceiver and goes to sleep for 150mS or 295mS. The “off” time is
approximately nine times the “on” time, resulting in a 10% duty cycle, greatly
reducing the transceiver’s current consumption. However, there may be a lag
time from when the transmitting transcoder activates to when the receiving
transcoder responds. The transcoder enters Receive Mode when it sees a valid
packet, so there would only be a lag for the first packet.
This cycle continues until data is received placing the transcoder into Receive
Mode, until a status input line is taken high placing it into Transmit Mode, or the
CRT/LRN line is taken high placing it into Serial, Learn, or Create Modes. If a
faster response time is desired, then the TR_PDN line can be left disconnected.
The MT Series transcoders are fully compatible with the MS Series encoders
and decoders. Tying the ENC_SEL line high makes the transcoder operate just
like an MS Series encoder. Tying this line low enables it to become an MS
decoder or a transcoder, depending on how it is set-up. This is described in detail
in the Transcoder Operation section.
There are two important issues of note when using the transcoders with the MS
Series. First, only two of the MS baud rates are supported by the MT; 9,600bps
and 28,800bps. Second, the MS Series will not respond to the advanced
features of the MT, like the custom data and Targeted Device Addressing.
The main advantage offered by the MT over the MS is the serial interface. This
allows a number of advanced options to be realized. Some other advantages
are:
in countries like the United States that average transmitter output power over
time.
take advantage of the advanced features without having to upgrade existing
transmitter stations based on the MS Series encoder.
unidirectional operation while other units require bidirectional operation.
Page 7