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Subject: RE: GDB and serial port
From: Nielsen Linus (ext) (Linus.Nielsen_at_elema.siemens.se)
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 non-destructive, and reversible.

The problem would be that I would have to hack the serial drivers
in my Linux kernel, and possibly also the gnu debugger. Not the way
I'd like to spend my next 2 weeks... :-)

I looked more closely in the schematics, and it may be possible
to connect the serial lines to the Line In without cutting the
connection to the MAS. There is a capacitor connected from the left
ear to GND that may interfere, but i'm not sure.

I don't care, since I can't think of any use for the
Line In anyway...

> * 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.

Uuuuh. Another week... :-)

> * 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.

Great tip. Thanks.

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

Good luck to you also! Happy hunting! :-)

/Linus



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