[libre-riscv-dev] DDR PHY

Cole Poirier colepoirier at gmail.com
Mon Feb 24 21:51:57 GMT 2020

> On Feb 24, 2020, at 9:28 AM, Luke Kenneth Casson Leighton <lkcl at lkcl.net> wrote:
> no it's fine, that's actually perfectly acceptable: i forgot about
> that.  if you *can* demonstrate that you've gone to the trouble of
> trying to find out for yourself, people on tech lists tend to react
> much better precisely because you've demonstrated an independent
> desire to find the answer.
>> The reason I was asking here is that I have looked it up and tried
>> to research this dozens of times over the past 6 months and still
>> not been able to understand what differentiates PHY from cores.
> i searched the words "ASIC PHY" and this came up:
> https://en.wikipedia.org/wiki/PHY

Yes this is where is started my search, unfortunately, the wikipedia
page is only about 200 words long and doesn’t properly explain the
difference between analogue PHY and digital circuits. The links it 
provides, all relate to ethernet and usb PHY links, that are similarly 
bare of helpful or relevant details and discuss again primarily the
microcontroller side of the PHY-digital logic system.

>> I actually have not been making judgments and then freezing
>> but have been using the method you describe.
> cool!  funny thing is, it applies just as well to languages as well as
> foreign languages.

Indeed it does! I quite enjoy languages as well.

>> It wasn’t that I was stuck, it’s that this was an unknown I’ve kept
>> returning to without being able to progress in my understanding.
>> With my new understanding that analogue design and synthesis
>> is in an entirely different electrical engineering domain and cannot
>> by synthesized from higher level languages like Verilog,
> oh... it can: analog *can* be written in HDL.. it's just that the
> layout is a bitch, because analog critically depends on many many more
> factors.
> these are circuits, after all.  look up circuit design - PCB and
> breadboards - it's exactly the same thing, just millions of times
> smaller.
> l.

Thanks for this Luke, this will provide fruitful ground for my
further exploration of the topic.

A resource I found today about this is a stanford presentation
and the accompanying slides in pdf form:
https://www-group.slac.stanford.edu/ais/publicDocs/presentation137.pdf <https://www-group.slac.stanford.edu/ais/publicDocs/presentation137.pdf>


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