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Subject: Re: Two-way serial comms with no internal mods...
From: jobarjo (jobarjo78_at_yahoo.fr)
Date: 2004-02-26


yes the hardware is easy: you just need a voltage converter (max232) with an
open drain transistor.
The protocol must be half duplex.

----- Original Message -----
From: "Joseph Jones" <joe_at_bumpycarrot.cjb.net>
To: "Rockbox development" <rockbox_at_cool.haxx.se>
Sent: Tuesday, February 24, 2004 11:44 AM
Subject: Re: Two-way serial comms with no internal mods...

> Linus Nielsen Feltzing wrote:
> > Joseph Jones wrote:
> >
> >> I talked about this earlier a bit...
> >>
> >> Since two-way communication is possible if we use both the line-in's
> >> pin and the in-line remote pin (man, that looks dumb written like that
> >> :) ),
> >
> >
> > I sure didn't understand what you meant :-)
> >
> > Two-way communication is possible by changing the direction of the only
> > pin there is, the remote control input pin.
> >
> >> would the system be able to talk to PC-style hardware through a serial
> >> port?
> >
> >
> > Yes, but not without special hardware in between, both for voltage
> > conversion and to split the Input and Output to the Rx and Tx pins of
> > the PC port. I don't know much about PC hardware, but I assume that it
> > can't change the direction of the serial port pins.
> >
> > Also, you need to write a special protocol for the PC, as the
> > communication can only go in one direction at a time.
> >
> > Linus
> >
> > _______________________________________________
> > http://cool.haxx.se/mailman/listinfo/rockbox
> >
> >
>
> Right, I think I've made a mis-understanding somewhere, I'm referring
> back to this thread:
> http://rockbox.haxx.se/mail/archive/rockbox-archive-2004-02/0166.shtml
>
> So it's only the in-line remote pin that can do any kind of I/O. I think
> somewhere I thought that the line-in had a 4th pin on it as well :/
>
> So, basically, could the techniques that are used to interface with an
> Alpine CD changer also be used to talk to PC-hardware, with no internal
> mods, but allowing for external mods?
>
> I hope that made a bit more sense :)
>
> Joe
> _______________________________________________
> http://cool.haxx.se/mailman/listinfo/rockbox

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