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56F84789 RAM problem

Question asked by Bob Cousins on Oct 5, 2015
Latest reply on Oct 6, 2015 by Bob Cousins

Hi there,

 

We have encountered a strange issue on certain 56F84789 chips. The last 4KW of RAM (0x3000-0x3FFF) is unusable. On read, each word is 0xFFFF. Attempting to write a word in that range has no effect.

 

We only find this problem with two specific date codes so far, all other date codes appear normal.

 

Some questions:

 

1) Is this a silicon fault?

2) Are there any configuration bits that could stop part of RAM not working as expected?

3) Has anyone seen this type of problem?

 

Cheers

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