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IrDA transceiver for PC

Introduction

Many of todays motherboard have option to connect IrDA module for infraredcommunication. But this module is not standard equipment and isn't easy to findhim. I examine option to build my own module and I discover, that only fewparts are needed. It's needed only standard IrDA transceiver and few partsdiscovered from datasheet. Majority of circuit is build-in in motherboard chipset.In the concrete covertor from serial signal to IrDA pulses. Pulses from IrDAtransceiver are negated!

Used parts

Like a IrDA transceiver is used chip HSDL1001 from Agilent Technologies(Hewlett Packard). It is available in Czech market GM Electronic. Next I wasuse resistor 10R/0.5W, which limits output current to infra LED. On the feedmust be used blocking capacitor 100nF close to HSDL1001. If on the feed willbe interference or cable will be longer it's needed electrolytic capacitor. I wasused 47uF/10V. Like a connector to motherboard is used 5 pins SIL pinterminal. I was use flat computer cable from old floppy. Lenght can't be longerthan 50cm. I have information from some people, that when you use shieldedcable, you can have longer cable. InfraRed communicatoin would operate to

about 150cm.

Mechanical construction without PCB

Circuit HSDL1001 is in SMD case and therefore is needed a little facility. I wasbuilt before problem how-to solder four SMD pins with using standardtransformer soldering iron and not to connect pins together. I was get flat cableand cut 6 wires, leave them together, razor isolation about 1 mm and plate themwith tin. Outer wires I was divorce in lenght about 5 mm (See picture). Now Iwas get HSDL1001, put the flat cable to pins and put the hot soldering iron toupper side of wires. First I was solder middle 4 wires and next outer two wires.

Lower side of wires was soldered to pins of IR part. When you connect some ofpins, you can use flux (colophony) or vacuum pump to disconnect them. Next

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you must solder ceramic capacitor to wires. You can bend down end of pin,place on the wire and solder. It's needed to work carefully and not connect pins.Electrolytic capacitor is soldered to pins of ceramic capacitor. It's better to havenot much hot soldering iron. Next we must solder resistor and wires to SILconnector. Some manufacturers have other wiring of connector. You must look

to the User's manual of your motherboard and compare wiring. My wiringdiagram is mostly used by Abit, ASUS, AOpen, MSI and maybe othermanufacturers.

BIOS

In a BIOS you must activate infrared port, usually SIR (Serial Infra Red) forCOM2. You must use IrDA mode or HPSIR.Some BIOSes have additional options. Many times works default settings.When you have options TxD, RxD - HiLo, HiHi, LoHi, LoLo, I recommend toNOT change options. In some Award BIOSes is marked negative. When you

manipulate with these settings, you can DESTROY IrDA transceiver or resistor.It's designed for pulses, not for continual lighting. You can recognize it by smell.Transceiver and resistor will be very hot too. In dark you will see dark red lightfrom one transceiver lens. I was test it and components was not destryed ;-)Next you can have option Duplex HALF/FULL. Leave it at HALF.Option "Transmit Delay" was not effect on my equipment. Leave it at default.

Software

Like a operational system you can you whatever with IrDA support. For example

Win98, Win2000 or Linux. After activation in bios (with or without connectedmodule) your OS would find new IrDA device. For example in Win98 arerequired drivers from installation CDROM. After correct installation you will seea small infra icon in a traybar. This icon signalling status of IrDA device. Whenyou approach some other IrDA device, Windows would automatically tells aboutfinded device for example mobile phone NOKIA 6210, or printer HP Laserjet4and they would wants drivers from you.At linux you must have IrDA subsystem compiled at kernel, respectively like akernel module.In a file /etc/modules.conf I have this:alias tty-ldisc-11 irtty

alias char-major-161 ircomm-ttyAt many linux distributions id IrDA subsystem built-in. At Mandrake I haveinstalled package "irda utils", in which are all needed programs and startupscript which provides automatic starting by using program irattach. At file/etc/sysconfig/irda I was change device to COM2 (DEVICE=/dev/ttyS1). Youcan check functionality by using program irdadump which dumps transmittedand received packets on IrDA device. My computer transmits once a 3 secondsfew packets. When I power-on my PalmVx device and he is close to computer, Isee his packets received to computer. It's possible to see device type. Nextinformation you will find at FAQ.

When it doesn't work

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When operational system doesn't find anything device, first check connectorwiring on motherboard, next BIOS settings and next software in operationalsystem and cable wiring.When you sure, that everything is allright, there can be a problem in powersupply lines interference. For me helps adding of electrolytic capacitor close to

HSDL1001 (See picture).There can be broken HSDL1001 part or some circuit on motherboard, but this isvery unlikely.

Links

I was get some interesting information from here:

http://www.irda.org/Infrared Data Association http://www.infraredport.com/Page with similar manual, but with other

circuit Telefunken TFDS4500. http://www.hw.cz/docs/irda/irda_uvod.htmlComplete description of

IrDA (Czech language) http://tuxmobil.org/Infrared-HOWTO/Infrared-HOWTO.htmlLinux

Infrared-HOWTO

Photographs

On the pictures are details of IrDA transceiver HSDL1001, pin connector andwhole cable.Electrolytic capacitor was later soldered to pins of existing ceramic capacitor.

http://www.irda.org/http://www.irda.org/http://www.infraredport.com/http://www.infraredport.com/http://www.hw.cz/docs/irda/irda_uvod.htmlhttp://www.hw.cz/docs/irda/irda_uvod.htmlhttp://tuxmobil.org/Infrared-HOWTO/Infrared-HOWTO.htmlhttp://tuxmobil.org/Infrared-HOWTO/Infrared-HOWTO.htmlhttp://www.hw.cz/docs/irda/irda_uvod.htmlhttp://www.infraredport.com/http://www.irda.org/

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