Application - Smart home (smart home system)

Home control panel by phone

To control the house by phone, there is a remote control in the

The remote control works as follows.

Working with an LPT port

Data via the LPT port is transmitted in parallel.

1 - The computer sends a signal to report

2-9 - Outputs through which data is sent to

10-17 - Inputs through which the printer communicates its

18-25 - Common wire.

Signals

program lpttest;

To check the operation of the program, you can simply connect an LED directly to the port, but

The simplest circuit consists of a transistor and a relay.

This drawback is not present in the circuit assembled using an optocoupler.

It provides galvanic isolation from the port.

But it’s better to abandon the relay altogether and control household appliances without leaving the

The device is assembled on a triac.

These are not all the schemes that can be used.