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Subject: Re: GDB and serial port
From: Andrew Jamieson (ajamiesn_at_mira.net)
Date: 2002-02-07


I'll try and check this for you tonight. A couple of points first tho:

* It's possible to organise a half duplex serial connection over one
wire, with a bit of circuit trickery, but it would be (a little) more effort
than what you are proposing, for less reward. The upside would be that the
mod would be none destructive, and reversible.

* You've probably already thought of this, but you could implement a
software UART for transmit, and switch to the HW UART for recieve (so you
could accelerate downloads, for instance). This would require no mods at
all .... but more SW development.

* From experience, copper winding wire is fantastic for soldering
directly to the pins of QFPs like the SH-1 processor. You need to burn off
the thin insulating layer (get a blob of solder on the iron, and then push
the wire though the blob a couple of times, until the wire 'tins' - ie the
insulator is burnt off and the wire looks silver instead of copper) and then
just solder it to the pin. You can get this wire in various sizes down to
0.2mm (IIRC), and it's sooooooo much better than thick plastic sheathed
stuff (such as wire wrap wire). Trust me.

That's it. I'll rip my JB appart now and see if I can determine where the
send line goes. Good luck .....

A

----- Original Message -----
From: "Nielsen Linus (ext)" <Linus.Nielsen_at_elema.siemens.se>
To: <rockbox_at_cool.haxx.se>
Sent: Wednesday, February 06, 2002 11:05 PM
Subject: GDB and serial port

> Hi everyone!
>
> I am writing a Gnu Debugger stub for the jukebox, and
> I plan to use serial port 0 as the debugging port.
> This requires a modification to the Jukebox since
> only the Rx line is connected to the remote control.
>
> I have the following idea:
>
> - Cut the wires from the Line In connector.
>
> - Connect Rx and Tx to the Line In connector
>
> - Connect Line In to the PC via an external RS232 converter
>
> I have one small problem. The Tx line from the SH1 is probably
> not connected to anything on the circuit board, so I will have
> to solder a wire directly to the CPU pin itself. Not for the
> weak hearted, I know.
>
> Does anyone know if the Tx line is connected to anything, or do
> I have to dust off my magnifying glass?
>
> /Linus
>



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