[Cryptech Tech] First hash via EIM

[Joachim Strömbergson]

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Aloha!

Шатов Павел wrote:
> If we only have one single flag, say WriteEnable, then our core will
> write its registers when it is asserted and always read them
> otherwise. If we have a set of two flags, say WriteEnable and
> ChipSelect, or WriteEnable and ReadEnable, then our core can be idle
> when it is not accessed. This is generally a good practice, because
> it lowers power consumption a bit by not switching anything when it
> is not actually needed. Your cores do have cs input, which I believe
> is exactly for this purpose, so I added two output flags in the EIM
> arbiter. Having Read and Write is actually equivalent to having
> ChipSelect and Write, becase ChipSelect = Write | Read and Read =
> (ChipSelect & ~Write). You can modify EIM arbiter to output
> ChipSelect and Write instead of Read and Write if you want.

Exactly so and that is how I modified the core selector.


> You are completely right, Joachim, having at least a draft memory map
> is vital. If you remember, I've already proposed my variant, you can
> use it as a starting point. I'm only dealing with FPGA-related stuff,
> so it would be great if someone with a bigger picture of the project
> in his head could create a rough version of EIM memory map and place
> it somewhere on the website. This person should also be responsible
> for keeping this table up to date in case we change something. In 
> Novena there are three additional address lines (A16-18). We are not
> using them right now actually. If you are afraid that we run out of
> address space, we can add them to our design.

Yes, your suggestion was good (having page zero for system info). I
think that if it is possible to increase the address space we should do
so right now. What would be the consequence in terms of access - you are
pushing 2+2 w16 for address anyway, or is it only one w16 word? That is,
if we move to more bits we need to do an extra write operation?

- -- 
Med vänlig hälsning, Yours

Joachim Strömbergson - Alltid i harmonisk svängning.
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 Joachim Strömbergson          Secworks AB          joachim at secworks.se
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