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Re: 8bit SRAM howto



Hello Pieter,

The 16bit bytewise write enable mode is the best way to do it as 
far as I can see. 

The shared RAM interface will not help you. It allows an external
device to read/write 8 bits at a time from/to the RAM, but the 
reads/writes to/from ETRAX 100LX are still 16 or 32 bits wide.

Best regards

Per Zander 

On Fri, 6 Jun 2003, Pieter Grimmerink wrote:

> Hello all,
> 
> I'm wondering what would be the best way to connect an 8 bit SRAM chip to the 
> Etrax100LX.
> This sram is battery backed-up, used for non-volatile status storage.
> 
> The best way I've found so far is in 16bit bytewise write enable mode.
> (R_BUS_CONFIG 0x100)
> But something like an 8bit bytewise write enable mode would be better ;-)
> 
> I could write a driver that makes sure that bytes written to the device are 
> translated to 16bit aligned write's to the SRAM, but I'm afraid that 
> implementing an mmap method would be impossible.
> 
> I noticed that the shared ram interface can be configured to use 8bit mode, 
> would it make any difference to configure this battery-backed-up SRAM chip as 
> a shared RAM?
> But I guess that does not have any effect on to the way the etrax accesses the 
> SRAM?
> 
> Best regards,
> 
> Pieter
> 
>