2010 by storm

Communications project

lirc = Linux infrared

remote control

Part of presentation

lirc

Introduction

to the project Component

and criteria

Faced

problems

INTRODUCTION TO THE PROJECT

lirc

lirc => Linux infrared remote control

Serial Port Receivers

reference http://www.lirc.org/receivers.html

Getting Started introduction

Use remote to send an IR signal and receive it in designed circuit and the control any thing in computer by a software .

Use remote !

COMPONENT AND CRITERIA

lirc

Components !

C1 - 4.7µF capacitor

Components !

D1 - 1N4148 diode

Components !

R1 - 4k7 resistor (4.7 kOhm)

Components !

IC2 - 78L05, 100mA, voltage regulator (TO-92 casing)

Components !

9-pin or 25-pin SUB-D socket

Components !

Tsop 1738

You should choose the 38 kHz carrier frequency types because most remote control standards use this frequency.

What happened if we use receiver with lower frequency ? The receiver won't stop working if your remote uses another frequency but the range will decrease.

Criteria

The pin-out of the voltage regulator usually looks like this (front view)

The pin-out of the tosp receiver usually looks like this (front view) 1,2,3 from left

Criteria

Serial port distribution looks like this

Criteria

The circuit of all receiver

Criteria

The power for the circuit comes from the RTS (request to send ) line of the serial port. D1 protects the circuit from the negative voltage that is usually on the RTS pin. The LIRC driver will change the serial port settings on initialization so that the circuit will get the necessary positive voltage. For most standard PC serial ports this will be approximately 10V. IC2 will convert the input voltage to exactly 5V.

Criteria

C1 is optional but for safety.

R1 is a pull-up that makes sure the DCD (Data carrier detect) line is on a

valid voltage level if the receiver does not receive anything.

Criteria

When an infrared signal is detected pulls DCD (Data carrier detect) down to ground, which should already be interpreted as a logical "1"

(DCD=0) by the serial port.

Criteria

Faced problems

lirc

1 * Due to low voltage in serial port that (6V or even less)

out from regulator 2v this circuit probably won't work on some notebooks

So you should make sure that your serial port delivers at least 8V of output voltage

Faced problems

Solution If your serial port provides less you can also try using a low-drop voltage regulator (e.g. LP 2950 CZ) instead of the regulator suggested here

2

* we can't use USB to serial converter the USB port or the internal 5V line to power the

circuit.

Faced problems

Then you won't need a voltage regulator at all.