feedback 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.
The DATA_IN line is connected directly to the data output of the receiver.
Data Lines D0 through D7 can be connected directly to the external
circuitry that is to be activated remotely. In this example, D5 is connected
directly to a piezoelectric buzzer, which will cause the buzzer to sound
when the D5 line on the encoder goes high. Line D6 will activate a relay
through a transistor buffer when it goes high. A buffer like this may be
needed if the decoder cannot source enough current or voltage to energize
the relay coil. The decoder will turn on the transistor, which will provide the
appropriate drive levels to the relay.
Typical System Setup
The HS Series offers an unmatched combination of features and security,
yet is easy for system designers and end users to operate. To demonstrate
this, let’s take a brief look at a typical user setup followed by more detailed
design information. The Typical Applications sections of the encoder and
decoder data guides show the circuit schematics on which these examples
are based.
1. Create and exchange a key from a decoder to an encoder.
The high security key is created and exchanged by placing the decoder
in the Create Key Mode. The decoder’s MODE_IND line LED will light to
indicate that the decoder has entered Create Key Mode. The decoder’s
CREATE_KEY button is then pressed ten times to create the key. After
the tenth press, the MODE_IND LED will turn off and the decoder
will send the key out of the KEY_OUT line. The MODE_IND LED on
the encoder will light to indicate that the key has been successfully
transferred.
2. Establish Control Permissions
The user establishes what buttons on the encoder will be recognized
by pressing the decoder LEARN button. The decoder’s MODE_IND
LED will start flashing and the user presses the buttons that will be
allowed access. Control Permissions are stored when the LEARN
button is pressed again or automatically after 17 seconds.
There are other powerful options such as programming a user PIN or
copying a decoder but these simple steps are all that is required for a
typical setup. It is really that simple for a manufacturer or end user to
setup the product!
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