Design with PC hardware standards in mind - is this a good idea in cost reducing - Page 1
Forum section: electronics / projects

author: technix
author_rank: Super Contributor
timestamp: August 03, 2015, 01:30:05 pm
content: So since the release of CubieBoard 8 released I wanted to buy one (despite the cost). But the form factor isn't really friendly when used as a daily driver. However...The board is just slightly smaller than a mini-ITX computer motherboardAllwinner A80 have almost a complete set of computer-like IO capabilities, even included a SATA port! But it is placed all around the board.So do you think if I decided to roll my own A80 board, is it a good idea to use the mini-ITX form factor, arrange the IO in the same fashion as a computer motherboard (including headers for front-facing USB and headphone jacks,) power the board with standard ATX power supply, and add a small microcontroller to handle the power button logic? Will this be a cost saving trick in the system design sense? Will this PC hardware compatibility (that is, this board can be used in any standard PC SFF chassis with standard PC hardware) promote sales?

author: eas
author_rank: Frequent Contributor
timestamp: August 03, 2015, 07:35:06 pm
content: Cubieboard8? Do you mean the CubieBoard4 with the A80 SoC? Or is there a new Cubieboard8 that I can't find any information about?In those small form factors and power envelopes, I think requiring a traditional ATX power supply is as much a hinderance as a help.Commonly available ATX power supplies are overkill and end up making up a significant portion of system cost and volume. The smaller form-factor, lower powered, ATX supplies are only slightly better. Efficiency isn't great in either case, or is at best hard to spec because typical power consumption is lower than the range speced for ATX PSUs. Compact DC-DC ATX PSUs are an option, but they represent an added expense and hassle.I'd instead look to including an onboard DC-DC power supply that would work with a 16-20V regulated DC power brick (19v probably being the most common). Include a header or two for powering SATA devices.Sensible I/O arrangements seem worthwhile, but that would be equally true of a board that could work in non-PC enclosures.Maybe the core question is how many daily-driver scenarios are there that really beg for having 4 wimpy cores, 4 slightly less wimpy cores, coupled with mediocre RAM and I/O bandwidth? To me, a daily-driver using ARM means Linux, and with Linux comes multi-core and multi-tasking and weak real-time abilities, all of which work against the value of lots of cores.

author: technix
author_rank: Super Contributor
timestamp: August 05, 2015, 03:59:54 am
content: Quote from: eas on August 03, 2015, 07:35:06 pmSo this case is rested. What about this scenario: designing a rack-mounted hardware like power supply or multimeter, using the microATX form factor of PC motherboards for main board and 5.25in optical drive form factor for front panel, and fit the entire assembly into a 2U rack mount server chassis?

author: westfw
author_rank: Super Contributor
timestamp: August 06, 2015, 12:43:49 am
content: QuoteThat's a good idea, if you can properly recognize when something has reached "standard" status, and if that standard lasts long enough to match your product lifetime...For instance, a past employer had a horrible track record WRT picking memory technology. FPM DIMMs, just before DDR took over, "Miniature Card" flash, etc :-( PCMCIA lasted for a credible timeframe, but the supposed "replacement" "ExpressCard" crashed and burned.

author: technix
author_rank: Super Contributor
timestamp: August 06, 2015, 02:18:22 pm
content: Quote from: westfw on August 06, 2015, 12:43:49 amStandards I am currently within consideration including:Mini-ITX and Micro-ATX computer motherboards for PCB sizes and mounting hole placement, coupled to...ATX12V power supply connectors. The combination of ATX12V and Mini-ITX/Micro-ATX form factors means that standard PC chassis and power supply can be used, including those recovered from decommissioned and dismantled PCs and rack-mount serversDDR3 SO-DIMM for DRAM with sufficient speed: normal laptop memory modules - ubiquitous, cheap to buy, and thanks to the SPD chip storing the timing information it is simple to use with FPGA-based DDR3 memory controllerSATA data cables for 2 differential pairs, Cat5e/Cat6 with TIA/EIA 568B pinout for 4 differential pairs - ubiquitous cables, cheap connectorsIDE UDMA-100/133 cables for lots of parallel lines - used to be ubiquitous, and I still have a stock of those, standard 0.1in spacing, and also easy to be used as a backplane connector with lots of pins.Continuing with the aforementioned A80 SoC board example, I will not include onboard memory like Cubieboard did but offer one DDR3 RAM module slot, and the system firmware will initialize the memory based on information stored in the SPD chips. Boot environment will probably be based on UEFI because of the firmware does almost as much as PC BIOS does during POST - initializing almost all major subsystems, but U-boot left a lot of hardware initializing to the kernel. Also despite being an ARM board this board will not use a serial console, although one serial port will be broken out as 9-pin RS232.

author: eas
author_rank: Frequent Contributor
timestamp: August 06, 2015, 08:19:51 pm
content: Quote from: technix on August 05, 2015, 03:59:54 amSure, 19" racks aren't going away any time soon (ever?). Is an A80 board with SATA I/O overkill in such applications over the likely lifespan of the A80? I don't know the answer, but it strikes me that it might be.On the other hand, if it is cheap enough, does it matter? I have some ideas for using a reasonably capable linux-capable module per-instrument. A 1GHz Cortex A8 or better core and 512GB RAM + ethernet are going to be enough for me, but if I can get an A80 with a couple GB for the price of a BeagleBone Black, well, I may never need to optimize any code.Quote from: technix on August 06, 2015, 02:18:22 pmNoting the obvious, that DDR3 and UDMA-100 cables are already on their way out. Not sure about SATA, yet, though the rise of SSDs is certainly applying pressure. So, just to be clear, this board is about scavenging up obsolete old stock?QuoteHow much work is UEFI firmware for this SoC? My understanding is that most of the ARM UEFI work has been focused on server targeted 64-bit chips, whereas the A80 seems to be targeted at tablets and set-top-boxes.

author: BravoV
author_rank: Super Contributor
timestamp: August 07, 2015, 12:03:10 am
content: Quote from: technix on August 03, 2015, 01:30:05 pmInterested, can you share a bit of your background or own past experiences in electronic design ? Some of your previous project examples that publicly available ?

author: technix
author_rank: Super Contributor
timestamp: August 07, 2015, 09:34:19 am
content: Quote from: BravoV on August 07, 2015, 12:03:10 amI am still tinkering and very much a newbie, albeit with a passion. Also I don't put my designs into public a lot.

author: nctnico
author_rank: Super Contributor
timestamp: August 07, 2015, 10:51:28 am
content: Quote from: eas on August 06, 2015, 08:19:51 pmNo it isn't. The price difference between a mSata SSD module and a similar sized SD card isn't that big but the mSata SSD is about 100 times faster than an SD card. I needed that kind of speed in one of my projects. Embedded Linux boots in 4 seconds from SSD. The only problem with SSD is that the data retention is 3 months (when switched off).@technix: you have to put an mSata slot on your board!

author: technix
author_rank: Super Contributor
timestamp: August 07, 2015, 03:13:23 pm
content: Quote from: nctnico on August 07, 2015, 10:51:28 amI'm gonna stick with a normal SATA socket instead of mSATA slot - you can buy passive adapters in the form factor of a 2.5in drive and accepts a mSATA card, so if I went with using standard ATX power supply I will go with a standard SATA cable socket so more drives can be used (mSATA SSD, normal SATA SSD, even spinning platters if you need to dump a few TBs into this box, which is actually good NAS/HTPC hardware) but if I used external power brick I may go to mSATA instead since it saves me of a SATA power socket.

author: technix
author_rank: Super Contributor
timestamp: August 07, 2015, 03:20:02 pm
content: Quote from: eas on August 06, 2015, 08:19:51 pmDDR3 will stay for quite a while - Intel's LGA1150 Broadwell still requires it, LGA1151 Skylake still supports it, and AMD still uses it, and DDR4 is still too expensive for normal consumers. And let's not forget the mobile section that is still moving from LPDDR2 to DDR3LWhen DDR4 start to pick up momentum and get cheaper I will also go that way.Quote from: eas on August 06, 2015, 08:19:51 pmLet's don't forget the Windows RT tablets, which is rocking a locked 32-bit ARM UEFI. I will ship an unlocked UEFI for sure, though.

author: westfw
author_rank: Super Contributor
timestamp: August 07, 2015, 04:28:45 pm
content: QuoteI thought that turned out to be a myth?

author: technix
author_rank: Super Contributor
timestamp: August 07, 2015, 07:04:42 pm
content: Quote from: westfw on August 07, 2015, 04:28:45 pmDefinitely a myth. SSD ata retention *can* be that bad especially on early stage TLC cells. But the most of us use MLC that have a minimum of 20 year of data retention based on brand you use - go with a more reputable brand if you need reliability like Intel or Kingston (Samsung is known to have questionable NAND chips from time to time though.)

author: nctnico
author_rank: Super Contributor
timestamp: August 07, 2015, 07:14:06 pm
content: Quote from: westfw on August 07, 2015, 04:28:45 pmNo. It says so in the specification (the ultra fine print) of various SSDs I looked at. Note that the number is valid when the SSD is not powered. Appearantly SSDs have a self refresh algorithm so data gets rewritten and bad blocks remapped automatically. Leaving it permanently on with not too much data on it could result in an extremely long data retention time.

author: eas
author_rank: Frequent Contributor
timestamp: August 07, 2015, 07:53:51 pm
content: Quote from: technix on August 07, 2015, 03:20:02 pmYou need to be planning for where the market will be once your design is actually done and produced. I could be wrong, but my impression is that people already expected DDR3 manufacturing to be EOL, with the DIMMs you are planning for soon to follow, and that it probably would be, if not for Intel stretching out parts of their roadmap. Regarding your point about low power DDR3 in the mobile market, how many of those devices are using laptop compatible SO-DIMMs? That you could make use of it seems counter to the point of creating a board that uses PC-standard subassemblies for cost savings.That may not be a big deal for the little niche you have your eye on, but its still good to be clear about that niche, which is why I was noting that it sounds like you are actually looking to borderline-obsolete standards in some cases, which to me implies that your cost-savings depends on the availability of new-old-stock inventory and used parts.And then there is the availability of the SoC you are (thinking of) building this all around. It's 1) in a fast moving market, and so may not have a long life itself (though there will probably be pin-compatible follow-ons) 2) It is a frankenchip, pasted together to appeal to device makers who want to look good to naive spec-hungry but price sensitive consumers.

author: technix
author_rank: Super Contributor
timestamp: August 07, 2015, 08:45:03 pm
content: Quote from: eas on August 07, 2015, 07:53:51 pmThose boards have about the same lifetime as computer motherboards - they are such consumer items after all. There is zero point keeping them produced after a year or two after introduction anyway, so lifetime is not a point here.The point of putting this "frankenchip" into this form factor is because it looked so like an Intel Bay Trail chip with ARM cores replacing amd64 ones, and with the PCIe root complex removed. So why can Bay Trail based desktop SoC board is available, why not this ARM based one? Those Bay Trail chips are used in HTPCs and home NAS boxes, and so can A80. PC part compatibility is useful here because users can buy this board, and scratch the Bay Trail board off their shopping list - all existing parts will still work.

author: westfw
author_rank: Super Contributor
timestamp: August 08, 2015, 12:00:22 am
content: Quotehere's the article I was thinking of:http://www.anandtech.com/show/9248/the-truth-about-ssd-data-retentionEssentially, it claims that the 3-month retention spec is minimum required for a drive that has already reached the maximum number of writes...

author: technix
author_rank: Super Contributor
timestamp: August 08, 2015, 06:27:44 am
content: Quote from: westfw on August 08, 2015, 12:00:22 amI would like to say that for a brand new SSD the data retention is better than 20 years. I personally have a used-for-a-few-years Intel 520 Series SSD sitting for half a year with my OS X installation inside and it never had any issue.If you need longer data retention, use a reputable brand like Kingston or Intel. This entire SSD concept was invented by Intel by the way.

author: Fsck
author_rank: Super Contributor
timestamp: August 08, 2015, 09:32:40 pm
content: Quote from: eas on August 06, 2015, 08:19:51 pmSATA will stick around as long as we still have spinning disks (which at the moment, seems to be an incredibly long time) as the current price point is simply leagues head of solid state storage. there's no need for a faster (and more troublesome to deal with) interface when drives are barely at half of their interface's maximum transfer rate.you shouldn't need to worry about it.hell, even if all the consumer and high performance SSDs migrate to higher performing interfaces, you'll probably still be able to find industrial SSDs with SATA. (you can still get IDE SSDs!)

author: nctnico
author_rank: Super Contributor
timestamp: August 08, 2015, 11:10:51 pm
content: Quote from: westfw on August 08, 2015, 12:00:22 amSo what do you promise your client? Anything beyond that what is specified is pure speculation...

author: technix
author_rank: Super Contributor
timestamp: August 09, 2015, 01:45:29 am
content: Quote from: Fsck on August 08, 2015, 09:32:40 pmRecently I just bought a Western Digital Green 6TB spinning platters disk. For storage capacities in the range of 4TB and above (as of now) there is still no single-drive SSD solutions, but spinning platters (which is going to stick to SATA for a very long time) are still forging ahead, with capacities like 10TB and beyond being released.

author: eas
author_rank: Frequent Contributor
timestamp: August 09, 2015, 02:36:55 am
content: Quote from: Fsck on August 08, 2015, 09:32:40 pmThis design exercise seems to be about finding some sort of low-cost sweet spot. Low-costs are usually found in the high-volume areas of the market.It is true that spinny disks still offer better cost/capacity but what does that really mean? For a basic consumer, a ~500GB SSD looks like runs $170 or so. It will be slow by SSD standards, but still beat the socks off the ~$50 spinny disk alternative. The spinny disk will have more capacity, but for a lot of people, that won't matter, because they'd never even fill 500GB, and it won't be long before a small SSD price/capacity competitive with a small spinny disk. For those in need of more capacity, spinny disks will hold out a bit longer, but the future isn't exactly bright. I've been looking to pick up another large (~4TB) , not particularly speedy, HDD for more than a year, and prices haven't really moved -- $30-40/TB still seems to be the norm.Yeah, SATA and spinny disks aren't about to disappear, but if they aren't cheap and plentiful, they seem to fall out of the sweet spot Technix seems to be trying to find.Of course, I'm not confident in my sense of where he's going with this...He started talking about a "daily driver," when I questioned that niche, he offered up an application in rack-mounted instrumentation, and now seems to have come nearly full-circle:Quote from: technix on August 07, 2015, 08:45:03 pmThis begs the question though, why not BayTrail, or AMD Kabini?I've been running small, inexpensive, low-power ARM boxes at home for about 5 years. I was interested in them because of cost, power efficiency, their lack of Intel/x86 and feeding my own curiosity and smug self-satisfaction. I was really interested in the first few generations of cheap ARM STB and HDMI sticks too, but never ended up getting any because I was uncomfortable with the GPL violations and lousy GPU and media codec support.So, what are the top three reasons that you, and the customers you are imagining, are going to choose this hypothetical A80-based board, rather than a BayTrail or Kabini board?I don't think it will be for excellent software support, even if you do create a nice UEFI for it. Price? I can order a quad-core 64-bit Bay Trail or Kabini or even Braswell for under $100 today and have it in hand next week. The cheapest A80 boards I can find are $100 with 2GB of RAM. How low can you go with an A80 board with SATA, SO-DIMM, etc? Performance? I haven't found great numbers, but I'm pretty sure that the smaller number of x86 cores will be more than outweighed by single-threaded performance. Power consumption? An A80 clocked for performance might beat the Kabini, but I suspect the Intel SoCs will be pretty close.How about the other A80 boards, why do people choose this hypothetical board over another one? A SATA connector is going to get some people's attention (like mine), provided the performance is actually reasonable and the price is right. I suspect that your ability to compete on price by letting people bring their own RAM, or use a standard PSU and a uATX or mITX and case is going to be at least partially offset by the added complexity of supporting commodity DIMMs, and the extra PCB space.This was part of my original point, which is that supporting PC standards for a low-cost SoC on a small board kind of works against those other advantages. Why do I want even a small mini-ITX case when all I'm going to put into it is a small board and maybe a 3.5" HDD? Why do I want the bulk of a 200W PSU when a 60W 19v laptop brick would be all I ever need?I'm sorry if I'm missing some important nuance and we've ended up talking past each other, but the sense I have gotten is that this project muddy, that it's too focused on the present and the past, rather than the future, and that it is trying to be good for lots of things without actually being right for anything. Pick a narrow focus, work outward from there.

author: charlespax
author_rank: Regular Contributor
timestamp: August 09, 2015, 10:32:29 am
content: Quote from: technix on August 03, 2015, 01:30:05 pmOne of the most valuable things I learned during my time at MakerBot is that making custom hardware is surprisingly affordable. There are off-the-shelf options that can be customized and there are many technologies that allow you to go fully custom. There is bent sheet metal, 3D printing, urethane casting, and a host of other technologies for making what you want. It turns out that accepting an industry standard or legacy hardware as a design constraint is often more trouble and less beautiful than going full custom.My advice is to design what you want as you want and only go with standard where the choice is or close to being arbitrary.

author: technix
author_rank: Super Contributor
timestamp: August 10, 2015, 07:25:33 pm
content: Quote from: eas on August 09, 2015, 02:36:55 amYou have missed the point of using a SATA port over mSATA at all. Yes it supports spinning platters, but the vast majority of SSDs also use this interface and mSATA ones can be used with a cheap, passive adapter - it is the "one interface that rules the 90% of them" solution.Also since the two main purposes of this board is HTPC and NAS, both requiring lots of storage, SSDs won't work at all. If you hold a few long running TV series and a few movies all in HD you can easily hit the 2TB mark that no consumer grade SSD currently offers.Rack mounting is for NAS purposes. Try cook up your own 19-inch rack - I can buy a half-depth (read fits in smaller racks for switches and network wirings), ready made one for about US$20. HTPC requires a nice-looking smal form factor chassis - try cook one of that up too.Also the A80 system can run without a heatsink and use fanless PSU since they use less power. So if you are the kind of people that needs a total moving-part-free system (e.g. recording studios or the most audiophile-grade HTPC) you can achieve one - a feat almost impossible with Bay Trail or Braswell.Quote from: eas on August 09, 2015, 02:36:55 amStack this against Bay Trail or Kabini or Braswell, at least it consumes less power. mITX is already slightly bigger than Cubieboard 4 so room is definitely a problem.About the other A80 boards (or Raspberry Pi, or BBB, or any popular ARM SoC board in the like,) having a way to find cheap, COTS chassis can be a very useful feature. CubieBoard 4 and PandaBoard never got a proper case. Raspberry Pi and BBB have lots of case but some of them cost almost as much as a mITX SFF chassis already. Also there are just so many PC case mod kits (e.g. for ones using this system as HTPC and modding them to fit into their living room) and old reuseable PC parts out there. You can take your granny's broken PC, gut it, put this board into it with an old RAM stick that was reject of your last computer upgrade, and keep all existing peripherals like that years old spinning platter disk and the too-underpowered-to-accept-upgrade power supply, and this will give her a useable machine for reading news and occasionally watch YouTube videos again. Hell maybe this will even allow her watch video in HD quality.