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Addressing 4MB flash memory from BF53x

Question asked by jeg on Aug 28, 2013
Latest reply on Sep 3, 2013 by Prashant

The BF53x allows 4 contiguous banks of 1MB asynchronous memory (512 x 16-bit words) to be accessed using 19 address lines A[19:1].  There are 4 AMS[3:0] lines to act as a chip select (one-hot inverse encoding) for each of the 4 banks.

 

I would like to connect a single 4MB flash device with 21 address lines.  I can think of 2 ways to do this:  1) add an external 4:2 encoder chip to map the AMS[3:0] lines to A[20:19] on the flash RAM, or 2) use the programmable flags to split the memory chip into 4 banks with a bit more overhead.  I'm leaning toward option 1.

 

Are there any easier methods to achieve this?  How about pitfalls with these approaches?

 

Thanks,

 

Jason

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