ENCODER OPERATION
Power Up
Upon power-up, the encoder sets the baud rate based on the state of the
SEL_BAUD line, pulls the TX_CNTL line low, and goes into a low-power sleep
mode. It will remain asleep until either the KEY_IN, SEND, or CREATE_PIN line
goes high. These lines place the encoder in either Get Key Mode, Send Mode,
or Create PIN Mode as described in the following sections.
Set Baud Rate
Pull The TX_CNTL
Line low
Go To Sleep &
Wake On Interrupt
ENCODER GET KEY MODE
When the encoder registers activity on the KEY_IN line, it will enter Get Key
Mode. In this mode, the encoder will look for an encryption key and user ID from
a decoder. When it receives this information, it will send a confirmation on the
DATA_OUT line to the decoder. It will then look for a final confirmation from the
decoder on the KEY_IN line. Once this confirmation is received, the encoder will
take the MODE_IND line high for one second to indicate that the key has been
successfully transferred and that the units may now work together.
Is The
KEY_IN Line
High?
Is The
CREATE_PIN
Line High?
Is The
SEND Line
High?
NO
NO
NO
YES
YES
YES
Pull The TX_CNTL
Line High
Set Timer
YES
NO
Is PIN
Active?
Is PIN
Enabled?
Pull The DATA
Line High
ENCODER SEND MODE
YES
YES
NO
Time Out?
When the SEND line goes high, the encoder will enter Send Mode. It will pull the
TX_CNTL line high to activate the transmitter and record the state of the data
lines. The encoder will then encrypt the data using the saved key 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.
Get Data Byte
Create Packet
Set 15-Second
Timer
YES
Is PIN
Active?
NO
Toggle
MODE_IND Line
NO
Is The
KEY_IN Line
High?
NO
Pull The DATA
Line Low
Set Timer To 2S
15 Second
Timer Time
Out?
YES
YES
Send Packet
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 Typical Applications
section of this data guide demonstrates the use of diodes for this purpose.
YES
Did The Timer
Expire?
NO
NO
Is The
Data Valid?
Is The
SEND Line
High?
YES
Is The
CREATE Line
High?
YES
NO
YES
Pull The TX_CNTL
Line High
NO
NO
Was A Button
Pressed?
NO
ENCODER CREATE PIN MODE
NO
Get Data
Is PIN
Enabled?
For higher security applications, the HS Series encoder has the option to set a
Personal Identification Number (PIN) to control access to the encoder. This PIN
is a four-digit combination of the eight data lines that must be entered before the
encoder will transmit any commands to the decoder.
NO
Was A Button
Pressed?
YES
YES
Was The
4th Button
Pressed?
NO
YES
NO
Is The
Data Valid?
Pull The TX_CNTL
Line Low
Create PIN Mode is entered by pressing the CREATE button on the encoder.
The MODE_IND line will begin flashing to indicate that the encoder is ready for
the PIN to be entered. The user will have 15 seconds to press any 4-button
combination to set the PIN. After the fourth button press, the MODE_IND line
will go low. If 4 buttons are not pressed or the CREATE line goes high within the
15 second window, no PIN will be set. Once created, the PIN can be erased only
by learning a new key from the decoder.
Was The
4th Button
Pressed?
NO
YES
YES
Set Timer From
SEL_TIMER Line
Did
Send And
Receive
Confirmation
Pass?
NO
Does PIN
Match?
YES
NO
Save PIN
Is The
SEND Line
High?
YES
YES
YES
Save Data
NO
Once the PIN has been set, the user must enter it correctly before the encoder
will transmit any commands. When entered, the encoder will be active for a
period of time set by the SEL_TIMER line. If this line is connected to ground, the
PIN will need to be entered after 15 minutes of inactivity. If this line is high, the
PIN will need to be entered after 30 seconds of inactivity. If no PIN is set, then
the encoder will activate as soon as the SEND line goes high.
Pull MODE_IND
High For 1 Second
NO
Did The Timer
Expire?
YES
Figure 7: HS Series Encoder Flowchart
Page 10
Page 11
5秒后页面跳转
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