Re: [ECOS] Re: unaligned half-word flash memory access on a EB55/AT91

[Marcel Ovidiu Achim <marcel.achim@ovidius-ib.de>]

Andrew Lunn schrieb:

>On Sat, May 07, 2005 at 10:26:57AM +0200, Marcel Ovidiu Achim wrote:
>  
>
>>Andrew Lunn schrieb:
>>
>>    
>>
>>>On Fri, May 06, 2005 at 08:51:17PM +0200, Marcel Ovidiu Achim wrote:
>>>
>>>
>>>      
>>>
>>>>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);
>>>> 
>>>>        
>>>>
>>>I don't think this is allowed. You have to do 16 bit accesses on 16
>>>bit aligned addresses. Maybe you want to do:
>>>
>>>HAL_WRITE_UINT8(0x01000000 + 0x555, 0xAA);
>>>HAL_WRITE_UINT8(0x01000000 + 0x556, 0x00);
>>>
>>>which will acheive the same but will do it in a legal way.
>>>
>>>      Andrew
>>>
>>>
>>>
>>>      
>>>
>>Your sugestion drives the NCS0 line twice and again the access is not 
>>alligned
>>(both read and write of the AT91 starts from A0 instead of A1). Since 
>>the memory cells of the flash
>>device are 16 bit long, while writing 0x556 means also writng to another 
>>cell instead
>>of 0x555.
>>
>>Please give more advice.
>>    
>>
>
>How do you have the MMU setup for that area of memory?
>
>        Andrew
>
>  
>
Well, the only way to set the memory behaviour that I konw is to 
configure the EBI_CSR0 register.
I set it up as follows.

// Set the EBI_CSR0 register for 16 bit access etc.
HAL_WRITE_UINT32(0xFFE00000, BA_0x010 | CSEN | EBI_BAT_BYTE_SELECT | EBI_TDF_0 | 4MB_PAGE | WSE | EBI_NWS_1 | EBI_DBW_16);







-- 
Mit freundlichen Grüssen / Best regards

Marcel Ovidiu Achim

OVIDIUS Ingenieurbüro
Vogelsangstr. 76
70197 Stuttgart/Germany

Tel.: +49 (0)711 62 03 600
Mobil: +49 (0)177 69 070 59
email: marcel.achim@ovidius-ib.de


-- 
Before posting, please read the FAQ: http://ecos.sourceware.org/fom/ecos
and search the list archive: http://ecos.sourceware.org/ml/ecos-discuss