[Arm-netbook] rk3399 what full schematics does lkcl want?

[Hrvoje Lasic]

On 19 May 2017 at 17:49, <ronwirring at safe-mail.net> wrote:

> -------- Original Message --------
> From: Luke Kenneth Casson Leighton <lkcl at lkcl.net>
> Apparently from: arm-netbook-bounces at lists.phcomp.co.uk
> To: Eco-Conscious Computing <arm-netbook at lists.phcomp.co.uk>
> Subject: Re: [Arm-netbook] rk3399 what full schematics does lkcl want?
> Date: Thu, 18 May 2017 23:35:37 +0100
>
> > ---
> > crowd-funded eco-conscious hardware: https://www.crowdsupply.com/eoma68
> >
> >
> > On Thu, May 18, 2017 at 8:51 PM,  <ronwirring at safe-mail.net> wrote:
> >
> > > lkcl says, he cannot make use of the rk3399 cpu
> >
> >  no, i did not say that.  i specifically said that it would be a total
> > waste of my time to *CONSIDER* using the rk3399 until *full reference
> > design CAD source files are available*
> >
> > >  because he does not have the full schematics.
> >
> >  no, i said full reference design PCB and schematic *CAD* files:
> > that's completely different, as full schematics are usually provided
> > in "PDF" format which are completely f*****g useless as you have to
> > re-enter absolutely everything into the CAD design system and it takes
> > weeks if not months... *and then you have to do the PCB as well*.
> >
> > > What are these schematics?
> >
> >  you mean full reference design PCB and schematic CAD files.
> >
> >  examples include:
> >
> >  * http://beagleboard.org/hardware/design  search that page for the
> > words "allegro" and "orcad"
> >  * https://www.kosagi.com/w/index.php?title=Novena_PVT_Design_Source
> > search that page for "altium source"
> >  * https://github.com/NextThingCo/CHIP-Hardware and again look for the
> > ".DSN" (orcad) and ".brd" (allegro) files
> >  * https://github.com/radxa/oshw/tree/master/rock_pro likewise
> >
> >  and many, many more.  Jetson TK1, Sabre Lite, Sabre iMX7 - there are
> > absolutely loads of examples.
> >
> >
> > >  Can you tell in advance what schematics are required?
> >
> >  you mean full reference design PCB and schematic CAD files.  yes you
> > can tell: the best ones contain both an example PMIC layout as well as
> > the DDR RAM layout.  the *absolute* best ones are a fully-working
> > board (typically named EVB - evaluation board) but a "beaglebone" or
> > somesuch will do just as well.
> >
> >  a full reference design basically allows a transformation into a
> > fully working Card to take place in as little as three weeks.
> >
> >  the ones that are a pain are the ones that *only* contain an example
> > DDR RAM layout to the processor.  but this alone saves LITERALLY
> > months of effort.
> >
> > > Can you name them?
> >
> >  name them... sort-of.
> >
> >  words to use when doing google searches include "BSP" or "EVB" but if
> > that doesn't work try "{processor name} space {PCB CAD Design Package
> > name}"
> >
> > > Or do you require all of the full schematics?
> >
> >  the more that is available the less time and money is wasted.
> >
> > > You do not know what schematics you require until you have read the
> full schematics?
> >
> >  if you just want to READ the schematics you can do that with the
> > auto-generated (read-only) PDF that is otherwise f******g useless for
> > doing actual modifications because it's a read-only output from the
> > CAD package.
> >
> >  obviously this will however allow you to assess whether the SOURCE of
> > the CAD files will be any good, such that you can decide whether
> > you're wasting your time or not.
> >
> >  for example, it's no good if you have a tiny board and the PDF shows
> > that the design has (and requires) 8 DDR RAM ICs.   or, if it uses
> > LPDDR RAM or uses POP (package-on-packagee) RAM, you need to make a
> > decision about that (see the neo900 nightmare they just had because
> > they picked a POP RAM)
> >
> >  but once you have reviewed the *READ-ONLY* PDF, even if you obtain
> > the schematic SOURCE file, you STILL cannot make a final decision
> > because you NEED TO SEE THE PCB CAD LAYOUT FILE AS WELL.
> >
> >  the PCB CAD file contains the footprints of the ICs, it contains
> > tracks laid out, ground planes all done and completed, and a huge
> > range of engineering expertise including R.F. and E.M. expertise of
> > the person who did the layout, all done, all of which you DO NOT HAVE
> > TO DUPLICATE.
> >
> >  but sometimes the distance between the SoC and the RAM ICs will be
> > too great: in a small PCB the ICs would not fit, so you would need to
> > consider *modifying* one of the most difficult and challenging areas
> > to get right (the DDR layout).  that's just nuts: you'd be wasting
> > your time, so it would be better to find a completely new layout that
> > someone else has already done.
> >
> >  sometimes the PMIC (power management ICs) are in the wrong place for
> > the target PCB size you want, so you have to work out how to move (or
> > re-lay-out) those, or replace them entirely.  that is a whole can of
> > worms on its own, so again it would be better to see if you can find a
> > new layout that's been tested and known to work.
> >
> >  basically it's a hell of a lot of work even to *evaluate* a Reference
> Design.
> >
> > l.
> >
>
>
>
>  I do not know about this. I understood it all wrong. I thought it was a
> matter of tfirefly withholding part of the full schematics.
> Is it correct to say, that the pdf schematics provide the required pieces
> of information for an eoma rk3399 pc card?
> Is it correct to say, that pdf full schematics are not easy usable for you
> in order to make an eoma rk3399 pc card?
> It is a matter of transforming pdf data into cad data? Having rk3399 cad
> data, you can make an eoma rk3399?
> Does tfirefly have the firefly rk3399 cad data?
> If so, why won't tfirefly make them public?
> Because a license prohibits it?
> Because competitors can use them?
> Lkcl, have you asked tfirefly to give you the full schematics cad data?
>
> Because I got to think, you said tfirefly is withholding some schematics,
> I wrote tfirefly asking them to email me the full schematics. Tfirefly
> never denied, that they had not made the full schematics public. They said,
> they could not disclose the full schematics. Maybe due to a lack of english
> skills on both sides.
>
> Then what should you ask tfirefly for? Full schematics cad data?
>
>
>
To undertake such a design reference design is needed. Without reference
design it is virtually impossible or so time consuming that it makes no
sense to even start. Luke pointed out some of most difficult parts that
include memory design but also all other high speed parts (hdmi, usb etc..)
then power section position i.e. position of capacitors, positions of power
supply ic, then how to route ever increasing number of lines and so on.
Even with well documented producers like TI or Freescale with all
documentation and all reference cad designs it is hard.
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