Embedded MPC860T & flash memory

Embedded MPC860T & flash memory

[Laurent Pinchart]

Hi everybody,

I'm developping a custom MPC860T board, and need 16MB of flash memory.

As I need to be able to write to the memory using the MTD layer, I was
wondering if it would be better to use 2 16-bit wide chips in
interleaved mode on a 32-bit bus (connecting them in parallel to the
bus, one of them storing D[0:15] and the other one D[16:31]), or to use
them in non-interleaved mode (non-overlapping address ranges) on a
16-bit bus. It seems that the Linux MTD layer can support both
configurations, but I don't have a deep knowledge of that code, and thus
would appreciate any advice.

I'll probably use AMD devices.

Thanks in advance for your help.

Laurent Pinchart


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Re: Embedded MPC860T & flash memory

[Wolfgang Denk]

Dear Laurent,

in message <3C7654F8.3010801@capflow.com> you wrote:
>
> As I need to be able to write to the memory using the MTD layer, I was
> wondering if it would be better to use 2 16-bit wide chips in
> interleaved mode on a 32-bit bus (connecting them in parallel to the
> bus, one of them storing D[0:15] and the other one D[16:31]), or to use
> them in non-interleaved mode (non-overlapping address ranges) on a
> 16-bit bus. It seems that the Linux MTD layer can support both
> configurations, but I don't have a deep knowledge of that code, and thus
> would appreciate any advice.

For the software it does not matter - both configurations will work.

For the performance it makes a BIG difference.

Go for a buswidth of 32 bits, i. e. use 2 chips in 16 bit mode in
parallel.

Wolfgang Denk

--
Software Engineering:  Embedded and Realtime Systems,  Embedded Linux
Phone: (+49)-8142-4596-87  Fax: (+49)-8142-4596-88  Email: wd@denx.de
"The trouble with doing something right the first time is that nobody
appreciates how difficult it was."                        - Walt West

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Re: Embedded MPC860T & flash memory

[Laurent Pinchart]

>
>
>For the software it does not matter - both configurations will work.
>
>For the performance it makes a BIG difference.
>
>Go for a buswidth of 32 bits, i. e. use 2 chips in 16 bit mode in
>parallel.
>
Ok, thanks for your answer.

Laurent Pinchart


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