IRDA CIRCUIT - HAYES MODEM EMULATOR

Hello

I have a NOKIA CELULAR PHONE that has a internal HAYES MODEM EMULATOR
and i use a DRL3 DATA CABLE for make communication using my PC
throught COMMx SERIAL PORT. The Hayes modem answer to my AT commands.

Recently, i used a microcontroller and i tried to connect to NOKIA
CELULAR PHONE without the DRL3 DATA CABLE and i got success too! I
removed the DRL3 cable and i did a direct connection. The Hayes modem
answered to my AT commands.

I see that the NOKIA has a IRDA option that allows to talk with HAYES
MODEM too. How is the circuit for transmit data for the modem? I
intend to use my COMMx SERIAL PORT for send AT commands to HAYES MODEM
using a SERIAL to IRDA converter, but, i don't know this circuit
converts 1's and 0's.

My intention is a microcontroller estabilish a comunication with
CELULAR HAYES MODEM without cables using HAYES PROTOCOL.

Thanks!

Miguel Wisintainer

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"Miguel Wisintainer" <[email protected]> wrote in message
news:[email protected]...
> I
> intend to use my COMMx SERIAL PORT for send AT commands to HAYES MODEM
> using a SERIAL to IRDA converter, but, i don't know this circuit
> converts 1's and 0's.

The IRDA port on your phone uses the standard IrDA protocol for sending and
receiving. It's not just as simple as connecting an IR LED to the transmit
cable and a IR Transistor to the receive as there's a whole protocol built
into it and I understand there's some hardware error detection.

Take a look at: http://www.irda.org/standards/specifications.asp

You can find the specification of the protocol and some information on
circuits (if I remember correctly).

As far as I understand it, you can use any standard IrDA transceiver to talk
directly to your phone's modem. The Hayes commands are understood by just
about every modem in existence these days as it has been the standard for
some 25 years.

Unfortunately it's not quite as simple as just wiring up an IR transceiver.
You need to manage the connection protocols, part of the IrDA specification
for maintaining multiple IR connections with a PC (such as phone, camera,
laptop, etc). Then manage the IrDA protocols to send/receive data.

It may be easier, for your needs, to simply ignore the in-built IR device on
the phone and make a custom IR/Serial lead. Essentially converting the
serial transmission from your device to IR, then from IR back to serial
which is plugged into the bottom of the phone. So in essence you're still
using a cable connection, but the cable turns into IR in the middle of the
cable.

You can get SOME success just using an IR LED on the transmit cable and an
IR transistor connected to an Op Amp on the receive cable. However, I
couldn't get it to connect at anything higher than 300 baud, and there's no
hardware flow control so it doesn't work very well.

Adam

"Adam Greatrix" <[email protected]> wrote in message news:<[email protected]>...
> "Miguel Wisintainer" <[email protected]> wrote in message
> news:[email protected]...
> > I
> > intend to use my COMMx SERIAL PORT for send AT commands to HAYES MODEM
> > using a SERIAL to IRDA converter, but, i don't know this circuit
> > converts 1's and 0's.
>
> The IRDA port on your phone uses the standard IrDA protocol for sending and
> receiving. It's not just as simple as connecting an IR LED to the transmit
> cable and a IR Transistor to the receive as there's a whole protocol built
> into it and I understand there's some hardware error detection.
>
> Take a look at: http://www.irda.org/standards/specifications.asp
>
> You can find the specification of the protocol and some information on
> circuits (if I remember correctly).
>
> As far as I understand it, you can use any standard IrDA transceiver to talk
> directly to your phone's modem. The Hayes commands are understood by just
> about every modem in existence these days as it has been the standard for
> some 25 years.
>
> Unfortunately it's not quite as simple as just wiring up an IR transceiver.
> You need to manage the connection protocols, part of the IrDA specification
> for maintaining multiple IR connections with a PC (such as phone, camera,
> laptop, etc). Then manage the IrDA protocols to send/receive data.
>
> It may be easier, for your needs, to simply ignore the in-built IR device on
> the phone and make a custom IR/Serial lead. Essentially converting the
> serial transmission from your device to IR, then from IR back to serial
> which is plugged into the bottom of the phone. So in essence you're still
> using a cable connection, but the cable turns into IR in the middle of the
> cable.
>
> You can get SOME success just using an IR LED on the transmit cable and an
> IR transistor connected to an Op Amp on the receive cable. However, I
> couldn't get it to connect at anything higher than 300 baud, and there's no
> hardware flow control so it doesn't work very well.
>
> Adam

Thank you very much Adam. You explain me all.
I had found a CHIP that make the conversion from SERIAL to IRDA, but,
at moment, i don[t have it price.
http://www.actisys.com/IrDAProd.html
If i know the correct protocol, will be a inexpensive for me. The
problem is that i dont want to plug back the phone, but use the IR.
Thanks again about your big e-mail!
Miguel