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Subject: Re: Serial Port Mod Question(s)

Re: Serial Port Mod Question(s)

From: [IDC]Dragon <idc-dragon_at_gmx.de>
Date: 2005-01-17

> I've searched the archives, and I've got a couple of questions about the
> mod that I can't seem to find the answer to:
>
> 1) First off, I have a recorder 20, with a version 1.0 mainboard PCB and a
> version 2.1B interface PCB Does anyone have a photo or two of the serial
> mod connection points for that PCB? The photos of the serial mod on the
> rockbox.org page are of a very different (player?) PCB.
>
> If not I'll trace try to trace the CPU pins for the Tx1 and Rx1 signals
> but
> I'm not so good at that sort of thing.

That's probably the best way. There are quite some different boards out
there. On mine, I found 2 convenient vias close to where the green wires
from the line in start, which I rewired. The serial input is also available
on the 3rd ring on the headphone plug, meant for remote control. You can
even abuse that for an output, but would have to bit-bang it. I did so for
my Alpine M-Bus plugin.

> 2) I'd like to keep my line-in connection untouched so I can record while
> also monitoring the serial port, can I use the SPDIF connection for my
> serial port?

Sure, you could re-route that, alternatively.

> I'm confused because it looks like the SPDIF should take a
> three part plug (it has three separate contacts) but the two ring contacts
> seem to be internally shorted either in the plug or on the board. For a
> serial port I need three connections right? (Tx, Rx, Ground)

Correct, as with digital in+out. The pins should not be connected. Try a
stereo cable.

> 3) Can plugins access the debug facility to send and receive serial data
> on
> SCR1? i.e. could I write a plugin that communicated with a device and
> downloaded/uploaded data to it via a UART link?

Yes. Either debug if compiled that way, or your own I/O routines. Again see
my M-Bus plugin:
http://rockbox.haxx.se/mail/archive/rockbox-archive-2003-11/0476.shtml
http://rockbox.haxx.se/mail/archive/rockbox-archive-2004-01/0778.shtml

Jrg

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Received on Mon Jan 17 22:45:38 2005

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