From: Andreas Schweigstill <andreas@schweigstill.de>
To: u-boot@lists.denx.de
Subject: [U-Boot-Users] Question about U-Boot in general and the AT91RM9200 in particular
Date: Thu, 04 Jan 2007 16:37:07 +0100 [thread overview]
Message-ID: <459D1F23.8050107@schweigstill.de> (raw)
In-Reply-To: <OF71937338.3DA0887F-ONC1257259.004E3A7A-C1257259.004E64D4@philips.com>
Hello!
Sascha Erlacher schrieb:
> this is not correct. As Wolfgang points out you can boot directly from NOR
> flash.
>
> It depends on the BootModeSelect (BMS) pin state of the AT91RM9200.
Unfortunately due to errata #37 external NOR flash will be accessed with
zero waitstates, which gives an access time of 20ns, so very fast and
expensive memory has to be used. And there also shouldn't be used any
external address decoders or bus buffers.
So using a serial boot ROM (Dataflash or EEPROM) usually will be the
best solution. Even a very small EEPROM can be suitable because the
program just has to modify bus timing for chip select 0 and jump to the
"slow" parallel Flash memory.
With best regards
Andreas
--
Dipl.-Phys. Andreas Schweigstill
Schweigstill IT | Embedded Systems
Schauenburgerstra?e 116, D-24118 Kiel, Germany
Phone: (+49) 431 5606-435, Fax: (+49) 431 5606-436
Mobile: (+49) 171 6921973, Web: http://www.schweigstill.de/
next prev parent reply other threads:[~2007-01-04 15:37 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-01-04 14:16 [U-Boot-Users] Question about U-Boot in general and the AT91RM9200 in particular Sascha Erlacher
2007-01-04 15:37 ` Andreas Schweigstill [this message]
2007-01-04 16:38 ` Ulf Samuelsson
[not found] <mailman.218930.1167876452.30209.u-boot-users@lists.sourceforge.net>
2007-01-04 11:41 ` Ivan Kuten
-- strict thread matches above, loose matches on Subject: below --
2007-01-03 22:49 Javier Ruere
2007-01-04 0:05 ` Wolfgang Denk
2007-01-04 12:20 ` Marco Cavallini
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