APPLICATION EXAMPLE
The MS encoder is ideal for registering button presses in remote control
applications. An example application circuit is shown in the figure below.
In this circuit, SPDT switches are used to select the baud rate so that pull-down
resistors are not needed. The data lines are connected to buttons and when any
button is pressed, the SEND line is pulled high and causes the encoder to
transmit. The diodes are used to prevent the voltage on one data line from
appearing on another data line.
If only one data line is needed, then it can be tied directly to the SEND line
without the need for the diodes.
None of the inputs have pull-up or pull-down resistors internally, so 100k
Ω pull-
down resistors are used on the data lines, SEND, and CREATE_ADDR. These
resistors are used to pull the lines to ground when the buttons are not being
pressed and ensure that they are always in a known state and not floating.
Without these resistors, the state of the lines could not be guaranteed and
encoder operation may not be predictable.
A LED indicator is attached to the MODE_IND line to provide visual feedback to
the user that an operation is taking place. This line will source a maximum of
25mA, so the limiting resistor may not be needed, depending on the LED chosen
and the brightness desired.
Outgoing encoded data will be sent out of the DATA_OUT line at the baud rate
determined by the state of the SEL_BAUD lines. This line can be connected
directly to the DATA_IN line of a Linx transmitter, used to modulate an infrared
diode, or connected to any other serial transmission medium.
The TX_CNTL line is connected to the PDN line of a Linx transmitter so that the
module will enter a low power state when not in use. A LED can also be
connected to the TX_CNTL line to provide visual indication that the encoder is
sending data.
In this example, the data lines are pulled high by simple pushbutton switches, but
many other methods may be employed. Trace contacts, reed switches or
microcontrollers are just some examples of other ways of pulling the data lines
high. The flexibility of the encoder combined with the associative options of the
matching decoder opens a whole new world of options for creative designers.
Page 11
Page 10
To Transmitter
100k
100k
220
100k
100k
100k
100k
100k
100k
100k
LICAL-ENC-MS001
D6
D7
SEL_BAUD0
SEL_BAUD1
GND
GND
GND
TX_CNTL
DATA_OUT
MODE_IND
D5
D4
D3
D2
VCC
VCC
D1
D0
SEND
CREATE_ADDR
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
220
To Transmitter PDN
100k
Figure 7: MS Series Encoder Application Circuit
SYSTEM EXAMPLE
The first step in using the encoder is to set the baud rate using the SPDT
switches. Next, a unique Code Word is created by pressing and holding the
button connected to the CREATE_ADDR line for as long as desired. While the
button is held, the LED will be on indicating that the Code Word is being created.
Once the button is released, the LED will start flashing. The data buttons that the
encoder is to access are now pressed. Pressing the CREATE_ADDR button
again makes the encoder save the new Code Word and Control Permissions,
turn off the LED, and go to sleep.
The decoder must now learn the Code Word for the system to be operational.
Please see the decoder design guide for instructions on how to do this. The MS
Series Master Development System implements this system, so please see the
User’s Guide for the kit for more system information and circuit schematics.
ONLINE RESOURCES
• Latest News
• Data Guides
• Application Notes
• Knowledgebase
• Software Updates
If you have questions regarding any Linx product and have Internet access,
make www.linxtechnologies.com your first stop. Our website is organized in an
intuitive format to immediately give you the answers you need. Day or night, the
Linx website gives you instant access to the latest information regarding the
products and services of Linx. It’s all here: manual and software updates,
application notes, a comprehensive knowledgebase, FCC information, and much
more. Be sure to visit often!
www.antennafactor.com
The Antenna Factor division of Linx offers
a diverse array of antenna styles, many of
which are optimized for use with our RF
modules. From innovative embeddable
antennas to low-cost whips, domes to
Yagis, and even GPS, Antenna Factor
likely has an antenna for you, or can
design one to meet your requirements.
®
www.linxtechnologies.com
English ▼
English
Chinese
German
Japanese
Russian
Korean
Spanish
French
Italian
Portuguese
Polish
Vietnamese
Indian
Mexican
British
New Zealand
