LICAL-ENC-MS001(2008) Ver la hoja de datos (PDF) - Unspecified
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LICAL-ENC-MS001 Datasheet PDF : 7 Pages
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ENCODER OPERATION
Upon power up, the encoder will set the baud rate based on the state of the
SEL_BAUD lines, pull the TX_CNTL line low, and go into a low-power sleep
mode. It will remain asleep until either the CREATE_ADDR or the SEND line
goes high. These lines will place the encoder in either Create Mode or Send
Mode as described in the following sections.
CREATE MODE
The Create Mode allows the generation of a unique address to ensure the
security of transmission and prevent unintentional operation of devices. The MS
encoder allows 16,777,216 (224) possible addresses. Creating the address is
remarkably straightforward.
When the CREATE_ADDR line is pulled high, the encoder randomizes the Code
Word continuously until the CREATE_ADDR line is pulled low. Once the encoder
registers the low line, the Code Word is saved and the encoder will begin to
toggle the MODE_IND line. This will indicate to the user that the encoder is ready
to accept the Control Permissions. Control Permissions are set by activating the
data lines that the user wants the encoder to have the authority to operate.
Pulling the CREATE_ADDR line high again will cause the encoder to save the
Control Permissions and go back to sleep. The Code Word will be sent with
every transmission when the SEND line is pulled high, but the encoder can only
activate the decoder data lines that are authorized by the Control Permissions.
The Code Word is learned by an MS Series decoder by placing the decoder into
Learn Mode and sending a transmission from the encoder. Please refer to the
MS Series Decoder Data Guide for full details.
The CREATE_ADDR line can be tied to a button or contact point accessible by
the user. With a simple press, the user will generate a unique address that
should never again require changing. Some designers may prefer to set a code
during production and not provide for change by the user.
The MODE_IND line allows for the connection of a LED or other device to
indicate to the user that the encoder is in Create Mode. Once the
CREATE_ADDR line goes high and the encoder enters Create Mode, the
MODE_IND line will go high and stay high until the CREATE_ADDR line goes
low. The MODE_IND line is capable of sourcing up to 25mA of current.
SEND MODE
When the SEND line goes high the encoder will enter Send Mode. The encoder
will pull the TX_CNTL line high to activate the transmitter, record the state of the
data lines, assemble the packet, and send it through the DATA_OUT line. It will
continue doing this for as long as the SEND line is high, updating the state of the
data lines with each transmission. Once SEND is pulled low the encoder will
finish the current transmission, pull TX_CNTL low to deactivate the transmitter,
and go to sleep.
For simple applications that require only a single input, SEND can be tied directly
to the data input line, allowing a single connection. If additional lines are used in
this manner, diodes or dual contact switches will be necessary to prevent voltage
on one data line from activating all of the data lines. The Application Example
section demonstrates the use of diodes for this purpose.
Page 8
Power Up
Set Baud Rate
Pull The TX_CNTL
Line Low
Sleep
Is The
NO
CREATE_ADDR
Line High?
YES
Is The
NO
SEND Line
High?
YES
Pull MODE_IND
Line High
Pull The TX_CNTL
Line High
Randomize Code
Word
Get the Data From
the Data Lines
YES
Is the
CREATE_ADDR
Line High?
NO
Pull MODE_IND
Line Low
Save Code Word
Start Toggling
MODE_IND
Compare With
Control
Permissions
Send the Data
Packet
Is The
SEND Line
High?
YES
NO
Pull The TX_CNTL
Line Low
Time Out?
YES
NO
Is the
YES
CREATE_ADDR
Line High?
NO
Poll Data Lines &
Update Control
Permissions
Save Control
Permissions
Pull MODE_IND
Line Low
Figure 6: MS Series Encoder Flowchart
Page 9
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