arm-netbook May 2017

arm-netbook@lists.phcomp.co.uk

47 participants
94 discussions

designing a low-cost decent 3d printing board
by Luke Kenneth Casson Leighton 23 May '17

23 May '17

hi all, ok so i've been looking around and the practice of creating a "modular" 3d printing electronics board is extremely common, thanks, many years ago, to the stupid, stupid decision to use prototyping (evaulation) plugin boards with 1.3 to 2.0 *amp* stepper ICs mounted onto micro-postage-stamp-sized PCBs. the problems these cause are endless. *some* people have actually read the datasheets associated with these driver ICs and have designed PCBs that respect the advice of the designers, by making sure that a large part of the PCB's copper is used as a heat-spreader. however the practice is not very common, and the people who make such boards are typically actual well-trained electronics engineers from the west, but who then use western PCB manufacturing and assembly plants, end result: very expensive boards ($120 to $200). as i would like to see both a low-cost board made *and* have a decent design, and having researched this for many weeks and found that what i am searching for DOES NOT EXIST i need some help. the board i believe is best started from is the Duet WIFI: https://github.com/T3P3/Duet this uses 2.5A TMC2660 "silent" steppers and importantly they're SPI-based. the idea is to cut the DuetWIFI down to the *absolute* bare minimum, turning it into the exact same thing as TRAMS (which uses the 1.3A TMC5130). so instead of an on-board ATSAM4, you use an arduino due. instead of WIFI you use a *standard arduino WIFI shield*. now, debatable is whether to split out the MOSFETs, endstops and thermistors into their own separate shield as well, which i feel might be sensible. in particular i would very much like to "stack" the steppers because i have a design where it is going to use *four* z-axes. in a first iteration those may be wired up as 2x 2-serial in parallel, however it would be very *very* nice to be able to just add a second "stack" of 4 z-axis steppers and use them to do automatic bed-levelling. so to do that it would mean having on-board jumpers that could select alternative GPIO pins... or maybe to use an I2C-based or SPI-based GPIO expander in order to reduce the amount of GPIO needed. however an alternative idea which would do just as well (without needing too much work) would be to have the expectation that there would be a "base board" into which *two* modular 4x TMC2660 stepper boards would be plugged, and an arduino due, *and* the MOSFET/endstop/thermistor board, and the *base* board would take care of GPIO expansion. anyone considering this: the layout on the DuetWIFI for its steppers is very *very* specific and should really not be touched or altered, merely cut away surrounding parts and add the necessary arduino-compatible headers. any takers for what is likely to be a quite straightforward project? l. --- crowd-funded eco-conscious hardware: https://www.crowdsupply.com/eoma68

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mali gpu reverse engineering lkcl may ignore
by ronwirring＠Safe-mail.net 22 May '17

22 May '17

Because I deleted a previously email about this subject, I start a new email. Info. Lkcl said, he is not in favor of reverse engineering a mali gpu. Because it is about 150000eu and new gpus will emerge during the reverse engineering and the outcome is uncertain. I agree on his arguments. I do not find them strong enough. Maybe lkcl assumed it was about a mali gpu on a pc card. It was not. My question was a general question about getting a broadly known mali gpu reverse engineered. In my email I referenced the https://www.kickstarter.com/projects/1771382379/firefly-rk3399-six-core-64-… because according to lkcl it is as fast as a duo core intel mainboard and only the mali gpu software is not source code. There is no new arm source code computer for sale. I think one should be provided. People must be able to get one. 150000eu is a crowd funding of 30000 people, each 5eu. I would pay an extra 5eu to be able to buy a source code computer. I do not know if 30000 people are interested or if they can agree on one board. You cannot get the mali source code faster, if you put more people on it?

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"lkcl may ignore" - please do not put that in subject lines
by Luke Kenneth Casson Leighton 22 May '17

22 May '17

so this is a nice experiment, but i'd really prefer it if people did not put my initials into subject lines. the result is dozens of repetitions which gets stale very very quickly: http://lists.phcomp.co.uk/pipermail/arm-netbook/2017-May/thread.html

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EOMA50
by Luke Kenneth Casson Leighton 21 May '17

21 May '17

http://elinux.org/Embedded_Open_Modular_Architecture/CompactFlash#Table_of_… if you recall, someone kindly pointed out that USB3.1 does *not* need two sets of Tx/Rx differential pairs but only one. so ironically that means that four pins on an extremely low pincount standard are now free. i thought, "ah ha! should add a 2nd USB2 to EOMA50!" ... but should it? one of the things about SoCs that are that small, they can fit onto a 43x30mm PCB is: the probability of the pincount being high enough for them to have two USB2 interfaces is... debatable. the GR8 definitely does but that's just one SoC. and if it *doesn't*... then fitting a USB hub on there to provide two USB2 interfaces is going to be a bitch-and-a-half. also, two new pins are definitely free: "by default" i would make those EINT2 and EINT3 *but* the other option is to make them SPI data lines 2 and 3 (for 4-bit DDR SPI). choices, choices... i'm leaning towards 2 extra EINTs particularly as i have an idea in mind for a modular smartphone, and the addition of extra EINT-capable GPIO would allow a sub-module standard which has an EINT line "per module". mind you a break-out GPIO device (such as oo i dunno... a $1 STM32F!) is probably going to be needed for that design concept anyway. bizarre, isn't it: you can either choose a $1.50 dedicated GPIO breakout IC which only has 12 pins... or you can choose a $1 EC which has 32 or 48 pins and has GPIO, USB, SPI, ADC, DAC, I2C, UART... so bizarre. anyway. thoughts appreciated. l. --- crowd-funded eco-conscious hardware: https://www.crowdsupply.com/eoma68

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GR8 based EOMA68 card / EOMA50
by Mike Leimon 21 May '17

21 May '17

> the layout's hilarious: the PCB is over 50% completely empty. Allow me to be the first to point out that for this very reason this SOC might be an excellent candidate for the first SOC to adapt to the EOMA50 standard. > remember that this *really is* the bare minimum - it'll be amazingly an under $10 BOM. And here is another good reason to use it as a first pick... -Mike

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mark an email no response from lkcl expected
by ronwirring＠Safe-mail.net 20 May '17

20 May '17

My questions are not important. It is interesting to get to know about the hardware discussed here. I do not know if lkcl has a policy of answering all emails. Can I mark an email 'no response from lkcl expected' such he knows not answering is an option if he has better things to do? Thank you lkcl for your work. It has to be difficult.

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does arm-netbook get a forum?
by ronwirring＠Safe-mail.net 20 May '17

20 May '17

Will a forum get created for the pc card instead of this email list?

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Re: [Arm-netbook] rk3399 what full schematics does lkcl want?
by ronwirring＠Safe-mail.net 20 May '17

20 May '17

-------- Original Message -------- From: Luke Kenneth Casson Leighton <lkcl(a)lkcl.net> Apparently from: arm-netbook-bounces(a)lists.phcomp.co.uk To: Eco-Conscious Computing <arm-netbook(a)lists.phcomp.co.uk> Subject: Re: [Arm-netbook] rk3399 what full schematics does lkcl want? Date: Fri, 19 May 2017 18:17:16 +0100 > --- > crowd-funded eco-conscious hardware: https://www.crowdsupply.com/eoma68 > > > On Fri, May 19, 2017 at 4:49 PM, <ronwirring(a)safe-mail.net> wrote: > > > 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. > > the t-firefly 3399 is designed, manufactured and sold by a third > party compapy (t-firefly) that has *nothing* to do with rockchip, the > manufacturer of the RK339 processor. > > > Is it correct to say, that the pdf schematics provide the required pieces of information for an eoma rk3399 pc card? > > that is incorrect in about two or three separate and distinct way. > > > Is it correct to say, that pdf full schematics are not easy usable for you in order to make an eoma rk3399 pc card? > > that would be correct in about two or three separate and distinct > ways, the implications of which are that it would cost about $30,000 > and take maybe 6 to 12 *months* to make an eoma rk3399 pc card purely > from a PDF schematic. > > > It is a matter of transforming pdf data into cad data? > > yes, which is a f******g stupid way to do it, as everything has to be > RE-ENTERED - by hand - into the CAD program, to make it "look" like > the PDF output. > > then once that's done you then have to do the PCB design *from* the > schematics, and that takes even longer. and will contain mistakes. > > it's basically a total waste of time and money to eveen consider. Is it difficult or takes a lot of time? I ask because the converting to cad files cannot be split up in numerous pieces and put on a website, where people can each solve one piece? > > > Having rk3399 cad data, you can make an eoma rk3399? > > correct! and it would, in total contrast to trying the incredibly > stupid idea of re-producing that CAD data taking almost a YEAR and > cost tens of thousands of dollars because you made dozens of mistakes, > take about 2-3 weeks instead. > > > Does tfirefly have the firefly rk3399 cad data? > > yes they do otherwise they would not be able to produce the Gerber > files to send off to the PCB manufacturing factory. > > > If so, why won't tfirefly make them public? > > because it's their proprietary and confidential data that's why! > they're a commercial company that wants to make money, having > absolutely nothing to do with rockchip (who are just a supplier of the > RK339 processor). > > why on earth would they destroy their own business by making it > possible for people to take the CAD files, create some gerbers, have > SOMEONE ELSE manufacture THEIR product and thus cut them completely > out of the loop? > > that would be very dumb of them to do, if their business is to make > money from selling t-firefly-rk3399 products, wouldn't it? > > > > Because a license prohibits it? > > no. > > > Because competitors can use them? > > correct. > > > Lkcl, have you asked tfirefly to give you the full schematics cad data? > > no... because they would think i was a bit dumb. or worse, wanted to > steal their business. i have no desire to piss them off. > > > > Because I got to think, you said tfirefly is withholding some schematics, > > no i did not say that. it may be true but i would not have > specifically said it. i may have said that *rockchip* has *not made > available the reference design* which is a totally different matter. > > you may have then thought "rockchip equals firefly". > > please try not to make cross-connections and/or correlations that > aren't actually the case. > > > > 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. > > no, you've just misunderstood their business model. please don't ask > them again, it's not fair to ask them to make public something which > will destroy their business model. > > > > Then what should you ask tfirefly for? Full schematics cad data? > > absolutely nothing. you don't ask them for anything. they're a > third party business - an OEM. > > and we also can't ask rockchip either, because we're not going to > order a million of their processors, cash up-front... *until* they > have made full CAD data available. > > classic catch 22 situation. > > so instead we wait - as i specifically, specifically said - until > rockchip's Reference Designs leak out onto the public internet and are > available on e.g. taobao or other site, for sale for $25. > > l. > > _______________________________________________ > arm-netbook mailing list arm-netbook(a)lists.phcomp.co.uk > http://lists.phcomp.co.uk/mailman/listinfo/arm-netbook > Send large attachments to arm-netbook(a)files.phcomp.co.uk

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Development boards for GuixSD Developers
by Louis Pearson 20 May '17

20 May '17

I asked over on the Guix development list if anyone would be interested in a dev board to help port GuixSD to the eoma68 board. So far there are two people who are interested. I've added them to http://rhombus-tech.net/allwinner_a10/ and I'm making sure I haven't jumped the gun or anything. Does this look okay?

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Re: [Arm-netbook] rk3399 what full schematics does lkcl want?
by ronwirring＠Safe-mail.net 20 May '17

20 May '17

-------- Original Message -------- From: Luke Kenneth Casson Leighton <lkcl(a)lkcl.net> Apparently from: arm-netbook-bounces(a)lists.phcomp.co.uk To: Eco-Conscious Computing <arm-netbook(a)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(a)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? > _______________________________________________ > arm-netbook mailing list arm-netbook(a)lists.phcomp.co.uk > http://lists.phcomp.co.uk/mailman/listinfo/arm-netbook > Send large attachments to arm-netbook(a)files.phcomp.co.uk

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arm-netbook May 2017