[U-Boot-Users] data bus bit reversal

[U-Boot-Users] data bus bit reversal

[DeLaGarza, Robert]

On Monday, March 31, 2003 2:24 PM, Wolfgang Denk [SMTP:wd at denx.de] wrote:
> > My question is this: are there other Flash programmers (such as the one 
in
> > the BDI2000) that can indeed compensate for the bit reversal?
>
> The standard firmware for the BDI2000 does not provide this  feature.
> But  I  know  that  Abatron provided such a solution as part of their
> excellent support - within less than a day AFAIR.
>
> I guess this solution is still available.
>

Thank you for the information.  The BDI-2000 was my first choice for use on 
this project, but for a variety of reasons (including my manager overriding 
my decision) we purchased the AMC/Metrowerks PowerTAP PRO.  I should not 
have allowed that!

I've contacted Metrowerks tech support, but I've yet to hear from them 
regarding this matter.  In the meantime, I will proceed with the 
code-in-SDRAM approach.

[U-Boot-Users] data bus bit reversal

[DeLaGarza, Robert]

I have a question that isn't strictly related to U-Boot.  I hope it's not 
unacceptable.

The old PPCBoot source included a macro used during Flash programming on a 
Musenki board (I suppose the U-Boot code still contains this, but I haven't 
checked).  The macro uses a look-up table to reverse the bits within a 
byte--MSB to LSB, LSB to MSB, and so forth.

We have a custom MPC8241 board with the same problem: the lines on the 
8-bit data bus between the PPC and the Flash device are reversed.  We're 
using an AMC/Metrowerks PowerTAP PRO for debugging and Flash programming, 
and it appears that there is no way to have the built-in Flash programming 
algorithms compensate for the bit reversal.

My question is this: are there other Flash programmers (such as the one in 
the BDI2000) that can indeed compensate for the bit reversal?

My current plan is to use custom Flash programming code running in SDRAM, 
but it would be nice if there was a tool that let me bypass this process.

Again, I hope this message isn't too far off-topic.  Thanks for any help.

-Robert DeLaGarza

[U-Boot-Users] data bus bit reversal

[Wolfgang Denk]

In message <01C2F78D.563A35A0.robdlg@att.net> you wrote:
> I have a question that isn't strictly related to U-Boot.  I hope it's not 
> unacceptable.

This is perfectly ok. I could not think of a  better  place  to  ask,
either.

> The old PPCBoot source included a macro used during Flash programming on a 
> Musenki board (I suppose the U-Boot code still contains this, but I haven't 

It should still be there. At least I'm not aware that it was thrown out.

> My question is this: are there other Flash programmers (such as the one in 
> the BDI2000) that can indeed compensate for the bit reversal?

The standard firmware for the BDI2000 does not provide this  feature.
But  I  know  that  Abatron provided such a solution as part of their
excellent support - within less than a day AFAIR.

I guess this solution is still available.

> My current plan is to use custom Flash programming code running in SDRAM, 
> but it would be nice if there was a tool that let me bypass this process.

We encountered similar problems before; this is one of the  very  few
cases  where I think that starting with a version of U-Boot that gets
loaded to RAM first actually makes sense.

> Again, I hope this message isn't too far off-topic.  Thanks for any help.

You are welcome.

Best regards,

Wolfgang Denk

-- 
Software Engineering:  Embedded and Realtime Systems,  Embedded Linux
Phone: (+49)-8142-4596-87  Fax: (+49)-8142-4596-88  Email: wd at denx.de
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