–

–

4

Theory of Operation

Transmitter Evaluation Board

The transmitter board is powered by an on-board 3V CR2032 lithium

battery. It has eight SPST pushbutton switches, the state of which is

encoded into a data stream using a Linx MS Series encoder. If a switch

is closed, the transmitter is enabled while the encoder captures the

pushbutton states for encoding and transmission. The encoder powers

down the transmitter when the button is released. Buttons S0 (D0) and

S1 (D1) are used to activate the LED and buzzer on the receiver board.

All of the data lines have been wired out to the header to the right of

the prototyping area and can be accessed for use with other switches,

contacts or microcontrollers.

Receiver Evaluation Board

The receiver board is powered by two AAA batteries. The LR Series

receiver exhibits a sensitivity of greater than –112dBm, so under optimum

line-of-sight conditions, the transmitter / receiver link can operate over

distances of up to 3,000 feet (1,000m). The data recovered by the LR

Series receiver is decoded by a MS Series decoder, and the data lines

are updated to match the state of the data lines (or pushbuttons) on the

transmitter board. To demonstrate this, one data line is used to drive an

LED while another is used to activate a buzzer. This board also has a

prototyping area with all of the receiver and decoder lines brought out to a

header.

Using the Kit

Using the kit is straightforward. Simply attach the antennas, turn on the

power and press buttons on the transmitter board. When S0 is pressed,

the buzzer sounds; when S1 is pressed, the LED turns on. When any

button (S0–S7) is pressed on the transmitter board, the corresponding

decoder output (D0–D7) is active high (V