From: Andreas Stemmer <groovingandi_at_gmx.de>
Date: Wed, 23 Jun 2004 15:53:22 +0200 (MEST)

> Does the uart boot mod does allow to boot even with an erased flash?
> How does it do that? is it a sh1 feature?
> Is there lot of difference with the full duplex serial mod?

As I understood it ([IDC]Dragon, please correct me if I'm wrong), it's a
feature the archos engineers built in for debugging purpose. The sh1 cpu has
some internal flash memory which is always executed at startup. It is
programmed to load the actual firmware from flash memory. But this
bootloader can do more: if you pull the lcd lines low during booting, it
gets you into this special uart boot mode, in which it accepts any code from
the serial line. I guess the archos engineers used it the same way as we do
now:as a fallback solution for the case that the content of the flash is
somehow garbled.

So you need three things: a bidirectional serial connection (as described in
the serial mod section on the rockbox homepage), the uart boot mod (which is
only pulling down some port pins) and [IDC]Dragon's nice serial boot tool
which manages the communication between your computer and the jukebox.

I'd love to help more, but I'm afraid I don't know too much about the
player/studio model and if the procedure is the same on those. I managed to
program a completely empty flash chip in my recorder this way.

Andreas

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Received on 2004-06-23