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Subject: RE: Update: Rockbox won't start from flash, any ideas?

RE: Update: Rockbox won't start from flash, any ideas?

From: Ofir Carny <>
Date: Thu, 26 Jun 2003 08:52:53 +0300

sorry if I'm just stating the obvious here, just my 2e-2$:

Did you try using an oscilloscope on the relevant lines (e.g. the lines going to the LCD and LCD chip),
and then emulating the behavior (including timing)? (it is best if all lines can be checked at once, maybe with a
logic input, to get things in sync).

I think that for some of the lines the end state may be sufficient (so it might be enough to put a
main(){while(1);} firmware, and then use a voltmeter on the lines).
Obviously some initializations need to take place (the oscilloscope part), and some lines probably just need to be
'driven' to activate their respective components (the voltmeter is enough part).

I once wrote something for what I think is a similar LCD, I'll try to find it (but it will take me some time), AFAIR
the initializations are fairly simple, consisting of very few bits of information, and mostly getting the timing right (giving components enough time to do their stuff).

If we have datasheets for some of the components, this will be much easier, because this is usually very simple stuff
(Don't know about the ATA though, no experience there).

Or maybe some of the CPU registers (or other CPU internals), need to be inited, I once had a lot of problems with
registers regulating the I/O mode of some of the CPU lines, this may usually be verified by externally looking at the
lines, and verifying that what you read/write to them is there. Many CPUs need you to say which line is input, which output,
and how do you plan to use them (e.g. serial I/F).

It may be easier to start, instead of by writing all this to flash, by adding to the Debug menus some more 'dangerous'
options, so it is easier (and safer) to update and test (e.g. lcd restart option, ATA restart).
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Received on 2003-06-26

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