From: Marcel Ovidiu Achim <marcel.achim@ovidius-ib.de>
To: ecos-discuss@ecos.sourceware.org, ecos-discuss@sources.redhat.com
Subject: [ECOS] unaligned half-word flash memory access on a EB55/AT91
Date: Fri, 06 May 2005 18:51:00 -0000 [thread overview]
Message-ID: <427BBCA5.3000203@ovidius-ib.de> (raw)
Hi all,
I am using eCos on an Atmel EB55 board. For an application I need to
store data into the on board flash device. My compiled code seams to
do an unaligned access to the on board flash which is enabled by the
NCS0 line.
This is a very simple code for a better understanding.
// Set the EBI_CSR0 register for 16 bit access etc.
HAL_WRITE_UINT32(0xFFE00000, 0x010030A1);
// Write 0xAA to address 0x555 of into the flash device.
// Note: this is not the whole prog. seq.
HAL_WRITE_UINT16(0x01000000 + 0x555, 0xAA);
An osciloscope shows that the write seqence did start from A0
instead of A1 which should be implicated for a half-word access.
The header file hal_io.h defines HAL_WRITE_UNIT16 to be of type
"short". However, for my compiled code short is 32bit (word) wide.
I expected "short" to be 16 bit. I compiled my code with gcc without
any flags.
I wonder why gcc compiles "short" into a "word" type. Do I need to
set a flag for gcc while compiling my code or do I even need to
recompile gcc itself? Is there any other register for the AT91 that
influence the MAS[0:1] bus for the ARM7TDMI to force the core to do
a half-word reading or writing?
Thanks for your advice and greetings from Stuttgart/Germany
Marcel Achim
--
Before posting, please read the FAQ: http://ecos.sourceware.org/fom/ecos
and search the list archive: http://ecos.sourceware.org/ml/ecos-discuss
WARNING: multiple messages have this Message-ID
From: Marcel Ovidiu Achim <marcel.achim@ovidius-ib.de>
To: ecos-discuss@ecos.sourceware.org, ecos-discuss@sources.redhat.com
Subject: [ECOS] unaligned half-word flash memory access on a EB55/AT91
Date: Fri, 06 May 2005 19:31:00 -0000 [thread overview]
Message-ID: <427BBCA5.3000203@ovidius-ib.de> (raw)
Message-ID: <20050506193100.MDonVRmKK_FGqY0-nsVWkLgrRYEqoxo_HO3cSqXi_O0@z> (raw)
Hi all,
I am using eCos on an Atmel EB55 board. For an application I need to
store data into the on board flash device. My compiled code seams to
do an unaligned access to the on board flash which is enabled by the
NCS0 line.
This is a very simple code for a better understanding.
// Set the EBI_CSR0 register for 16 bit access etc.
HAL_WRITE_UINT32(0xFFE00000, 0x010030A1);
// Write 0xAA to address 0x555 of into the flash device.
// Note: this is not the whole prog. seq.
HAL_WRITE_UINT16(0x01000000 + 0x555, 0xAA);
An osciloscope shows that the write seqence did start from A0
instead of A1 which should be implicated for a half-word access.
The header file hal_io.h defines HAL_WRITE_UNIT16 to be of type
"short". However, for my compiled code short is 32bit (word) wide.
I expected "short" to be 16 bit. I compiled my code with gcc without
any flags.
I wonder why gcc compiles "short" into a "word" type. Do I need to
set a flag for gcc while compiling my code or do I even need to
recompile gcc itself? Is there any other register for the AT91 that
influence the MAS[0:1] bus for the ARM7TDMI to force the core to do
a half-word reading or writing?
Thanks for your advice and greetings from Stuttgart/Germany
Marcel Achim
--
Before posting, please read the FAQ: http://ecos.sourceware.org/fom/ecos
and search the list archive: http://ecos.sourceware.org/ml/ecos-discuss
next reply other threads:[~2005-05-06 18:51 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-05-06 18:51 Marcel Ovidiu Achim [this message]
2005-05-06 19:31 ` Marcel Ovidiu Achim
2005-05-06 20:12 ` Andrew Lunn
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