Project on Infrared technology.....

hye everyone!!!!
Right now I'm doing my final year project in communication engineering field.
My project entitle, "Wireless PC-to-PC Communication Via Infrared". Currently I'm stuck in the middle of the project because I cannot get the most important component in my project which is the HSDL-8000 (works as an IrDA transceiver). I dunno elsewhere but in my location here, almost everybody I asked never heard of it before and it is almost imposible to find that component here. I've also search over the internet to find if there are any international company that selling the component but so far it turn out to be none. Now, I'm done with this Ir transceiver circuit and I'm planning to use another circuit that use components that can easily be found in the market today. I was hoping you guys can give me some hint what components should I use in my new circuit. It would really help me if you can give me a sample of Ir transceiver circuit diagram that can works. Below are some informations of my project:

Title:Wireless PC-to-PC Communication Via Infrared
Objective: To develope a serial wireless communication between 2 PCs that enable any type of data transfers from one PC to another PC nearby.
Type of communication : Using PC's serial port that support bit rate up to 115.2kbps. The Ir transceiver are connected to PC's serial port.
Interface: Currently I've developed an interface using Visual Basic 6.0 and hopefully that circuit can fit perfectly with the new circuit.


Please help me..... Thanks for your time and concideration....

ok..here u have control over every bit that is transmitted from the port. so i don't think u require an IrDA TxRx. use a rs232 level shifter +(modulator)+ IR diode , for receiver u need to build the IR receiver using photodiode from scratch(ie u cannot use ready made receiver modules, since operatin freq is high),diagrams availabe in net.
remember about LOS limitations and receiver sensitivity + noise.

RS232 level shifter..

hye akg!!!
Thanks for your response earlier. You stated that I wouldn't be needed an IrDA TxRx in my project. I just need to make use of the RS232 level shifter +modulator+IR diode for this project. Actually I'm not so familiar with the RS232 level shifter, or in exact word never heard of it before (sorry, my bad). Actually what does this RS232 level shifter do, and can you tell me more detail on this shifter? Thanks..

Re: RS232 level shifter..

achaizs said:

hye akg!!!
Thanks for your response earlier. You stated that I wouldn't be needed an IrDA TxRx in my project. I just need to make use of the RS232 level shifter +modulator+IR diode for this project. Actually I'm not so familiar with the RS232 level shifter, or in exact word never heard of it before (sorry, my bad). Actually what does this RS232 level shifter do, and can you tell me more detail on this shifter? Thanks..

Click to expand...

rs232 is bipolar ie -ve volts for 1 and +ve for 0 , u need to make it unipolar ie 0 and +ve . there is a MAX* ic that does this ( i don't remember its number ..may be some one will).if u got the concept , that will be better.

about MAX****

hye again akg!!!
You have mention about the MAX**** chip earlier in your reply. In my previous circuit, there is one chip which is MAX232N. I think this has the relation with the MAX chip you mentioned before. You were saying that this MAX chip change the bipolar ie -ve volts for 1 and +ve for 0 into unipolar ie 0 and +ve. If I have this chip, meaning that those job has been done for me right? What about the modulator? Can you decribe a little bit more on it.. Thanks akg........

Re: about MAX****

achaizs said:

hye again akg!!!
You have mention about the MAX**** chip earlier in your reply. In my previous circuit, there is one chip which is MAX232N. I think this has the relation with the MAX chip you mentioned before. You were saying that this MAX chip change the bipolar ie -ve volts for 1 and +ve for 0 into unipolar ie 0 and +ve. If I have this chip, meaning that those job has been done for me right? What about the modulator? Can you decribe a little bit more on it.. Thanks akg........

Click to expand...

yes i think that can be used. a modulator/encoder may be needed to effective transmission , it is recommended for higher noise immunity.
search for manchestor encoding for coding method, and TTL/CMOS gated oscillator can be used as a modulator.

Another option is to use a laser for the transmitter and ldr or solar panel for the receiver. I know this works fine for transmitting analogue audio with necessary amp and preamp stages. May be worth trying due to ample availability of components.

i would use this:
you have a COM port TX pin (3 or 2 I cant remember)
you connect this to AND gate input no1
the other input is connected to NE555 output and this 555 creates 38kHz pulses for the IR modulation
on the other end in the COM port is connected a IR reciever that is in every remote operated unit (TV, Radio, VCR etc). this then captures the data and sends it to PC's COM port RX pin (2 or 3 cant remember). also this circut needs extra powersuply so 5V must be also connected to those circuits. can be taken from MOLEX conenction in PC or something external. if you can hack USB then this is also a pace this can be obtained.

And then you put both of them in COM ports and there you go. only SOFtware writing left to operate this thing.

Unfortunately you can't send plain RS232 over an IR link in that way, RS232 relies on the accurate width of the pulses, the IR link doesn't maintain the width of the pulse accurately enough. This is why various encoding schemes are used, see the Sony SIRC's system (which uses three wildly different width pulses), or the Philips RC5 (which uses Manchester coding).

I couldn't find this reciever circuit on the web and I too am trying to build one from scratch.
Maybe we could help each other out. :wink:
Here is something I found out .
I use a 567 decoder chip for a frequency detector.
I am using a clock input to pin 6 for detection frequency,instead of a resistor and capacitor.
This saves components and lets me use the same clock for transmitter and your detector.
I think my problem is the diode amplifier.
Please post your solution.

bloody-orc said:

i would use this:
you have a COM port TX pin (3 or 2 I cant remember)
you connect this to AND gate input no1
the other input is connected to NE555 output and this 555 creates 38kHz pulses for the IR modulation
on the other end in the COM port is connected a IR reciever that is in every remote operated unit (TV, Radio, VCR etc). this then captures the data and sends it to PC's COM port RX pin (2 or 3 cant remember). also this circut needs extra powersuply so 5V must be also connected to those circuits. can be taken from MOLEX conenction in PC or something external. if you can hack USB then this is also a pace this can be obtained.

And then you put both of them in COM ports and there you go. only SOFtware writing left to operate this thing.

Click to expand...

Can ordinary IR diode trasmit data? I mean if I'm going to build a circuit to transmit video data type, can this ordinary IR diode used in TV and VCR remote control do this kind of job? I really need to know this first.

cyb0rg777 said:

I couldn't find this reciever circuit on the web and I too am trying to build one from scratch.
Maybe we could help each other out. :wink:
Here is something I found out .
I use a 567 decoder chip for a frequency detector.
I am using a clock input to pin 6 for detection frequency,instead of a resistor and capacitor.
This saves components and lets me use the same clock for transmitter and your detector.
I think my problem is the diode amplifier.
Please post your solution.

Click to expand...

hye cyborg777!! actually I'm not so familiar with this diode amplifier you mentioned there. In my previous circuit I used a special IC which is the HSDL8000 as the TxRx medium. Unfortunately I cannot find this IC anywhere. Other components are the MAX232N IC and a few capacitors.
That's why I'm thinking of a replacement of my circuit right now.

Nigel Goodwin said:

Unfortunately you can't send plain RS232 over an IR link in that way, RS232 relies on the accurate width of the pulses, the IR link doesn't maintain the width of the pulse accurately enough. This is why various encoding schemes are used, see the Sony SIRC's system (which uses three wildly different width pulses), or the Philips RC5 (which uses Manchester coding).

Click to expand...

I thought that the job has been done by the MAX232N Ic. Should I used the components that you mentioned?

achaizs said:

I thought that the job has been done by the MAX232N Ic. Should I used the components that you mentioned?

Click to expand...

no that ic just a level shifter and converter, not an encoder.

please, can anybody give me a sample of circuit. It's hard for me to design it myself.

One more question, I really want to know whether IR Diode in tv or vcr remote control can be used to transmit video data type to another TxRx circuit?

achaizs said:

One more question, I really want to know whether IR Diode in tv or vcr remote control can be used to transmit video data type to another TxRx circuit?

Click to expand...

yes . u can use that

Then if I use this IR Diode, how about the max speed of bit transfer for this circuit? I wonder if it gonna be too slow for serial data transfer..

achaizs said:

Then if I use this IR Diode, how about the max speed of bit transfer for this circuit? I wonder if it gonna be too slow for serial data transfer..

Click to expand...

all the components in the system has it's own part in speed.
what is ur requirement.?

max speed for serial port which is 1115 kbps to 4 mbps