On Mon, 4 Jul 2016 18:02:13 -0500, you wrote: >When you design low cost hardware, you have to make certain decisions to >get the cost down. > >1) As few components as possible. granted, no problem with that.
>2) Limit the application. Only one application, do we know what the application is? Apparently people tend to think that this can do anything. >3) Push as much cost outside, for example the power supply. hmmm, then that says you have not as much control over the power supply as you might want. Certainly not as much as you may like. >4) Lowest cost components. no problem. >5) Limit the features. no problem. It does what it does. >6) Cut the profit. diminishing returns. > >Yes, there are several things I could have done different. Many of these no >one has even identified. Perhaps it might be interesting to know what they were... Not criticizing, but to know design alternatives might be nice. >But if I had, you would not have bought it because >it cost too much. After all hardware is supposed to be cheap. I'd personally disagree. Hardware costs as much as you pay for, and does what you design it to do. I, for one, am willing to pay more for more capability, within reason. Not your typical consumer, though..... >That is where >the value is, in the price. Not the value.. Then you're designing to a price point, and that's a different thing entirely. > >Nobody asked how I took it from $89 to $49. They just bought them up and >complained that it didn't do all the things they wanted it to do for $49. I'm not even aware that your initial design was 89 dollars. I might not have bought it for that, but that would have been my decision. "I" however, am not "they".... but there are a lot more of "them" than there are of me.... Not practical for you to put too many blank pads on a board and expect the user to solder parts in. I do, because I can build the boards. Your average hobby type... not likely I suspect. > >If anyone of you want to change the design, add more features, make it more >robust, add more cost, increase the price, manufacture it and sell it, by >all means, go ahead. I am sure there will b a few folks that value the >hardware and recognize that value, and will pay for it. If I needed something with that capability, I'd probably buy it because my cost preference on a PC board is 2 layers and not 4 or 6. I don't have the money to develop a product at this level, nor do I have the desire, nor perhaps the time or expertise. The cost would, of course, determine how many I'd use, and for what, but that's a simple economic decision. Then there's the engineering decision. > >But, I suspect the majority will complain that it is too expensive and will >stay with the BBB and instead ask how to flash the latest image in the BBB >and why does my my GPIO does not work.. Can't help you with that.... Harvey > > >On Mon, Jul 4, 2016 at 5:46 PM, John Syne <john3...@gmail.com> wrote: > >> Harvey, you raised several very good points. I cannot say I disagree with >> anything you said. >> >> Regards, >> John >> >> >> >> >> > On Jul 4, 2016, at 3:36 PM, Harvey White <ma...@dragonworks.info> wrote: >> > >> > On Mon, 4 Jul 2016 15:13:00 -0700, you wrote: >> > >> >> Pay no attention to William. You comments are welcome and Gerald has >> accepted your comments as valuable input by thanking your for your >> feedback. Now, let me address your concerns: >> > >> > From my own engineering standpoint (and opinions will, of course, >> > vary): >> >> >> >> 1) The power supply used to power the BBB should be selected so that it >> does not damage the BBB, so a 2A power supply was specified. If you wish to >> change that specification, then the onus is on you to verify that a 4A >> power supply will not damage the BBB. Your conclusion that is may damage >> the BBB means that you should not use a 4A power supply. In addition, a >> power supply that is spec’d at 4A should not shutdown when it sees a 4A >> load, but rather, it should current limit at 4A. If the power supply is >> spec’d at 4A, then 4A should not be treated as a short circuit. >> > >> > I would have designed the power supply circuitry so that with a power >> > supply of appropriate minimum rating, the maximum rating would not >> > have mattered. Using a power supply with a maximum current rating to >> > avoid damaging circuitry is not (again, IMHO) the best solution. If, >> > because of economic considerations, that decision is made, then it is >> > imperative of the designer to put this information specifically in the >> > power supply recommendations. Not doing this leads to damage, doing >> > this puts the responsibility on the user. Is this a "before the >> > design/after the design"? I don't know, and I don't remember (either >> > way) if this warning was ever in the power supply requirements. >> > Hindsight is 20/20, of course. If it's that important, then perhaps >> > the documentation needs to be changed. Decision not up to me. >> > >> > >> >> 2) The TI spec for the TPS65217C is a general recommendation as they >> are unaware of how you are going to use the part. The BBB SYS_5V powers >> several subsystems, including HDMI, I/O (VDD_3V3B) and USB. Clearly you >> could move the 100uF to the other side of the TPS2051, but then you need an >> additional capacitor on the SYS_5V which increases the cost and doesn’t >> provide any clear benefit, if you choose the correct power supply. >> > >> > "correct power supply" bothers me. I'm familiar with minimum current >> > capacity, voltage limits, short circuit current limits (infrequently >> > applied). Again, "a 4 amp power supply will allow the board to damage >> > itself, so we depend on a 2 amp maximum supply to avoid damage." This >> > could be discussed a bit.... >> > >> > >> >> 3) As Gerald has pointed out, the BBB is just a reference design. It >> was designed as a low cost solution which meant that tradeoffs were >> required to keep the price low. Clearly things could have been done >> differently, but then the BBB price would have been much higher and the >> board larger. Given that most users would probably not need these extra >> features, they were not incorporated into the current design. There are >> several spinoffs of the BBB, some with wifi, some with more RAM, etc, but >> none have been as successful as the BBB. >> > >> > Hmmm, well, perhaps (although not required) it might be nice to know >> > what the engineering limitations are of the design. >> > >> > I've seen 1) the ones I know about, and 2) the ones I haven't found >> > out yet... and 3) the ones people are going to have to tell me >> > about... >> > >> > and I do like paranoid designs..... >> > >> > Harvey >> > >> > >> >> 4) While I have provided Gerald input into both the BBB and >> BeagleBoard-x15 designs, I ultimately defer to his judgement because he has >> the track record or having designed several products that are very >> successful. >> >> >> >> From my prospective, the BBB design is good, but your input was none >> the less valuable. >> >> >> >> Regards, >> >> John >> >> >> >> >> >> >> >> >> >>> On Jul 4, 2016, at 2:11 PM, William Hermans <yyrk...@gmail.com> wrote: >> >>> >> >>> kzsoltkzsolt, >> >>> >> >>> I would like to point out to you that you're talking to *the* person >> who designed the beaglebones, who also used to work for Texas Instruments >> at some point in his career. Someone who has made his designs free of >> charge to the public, which he has made perfectly clear to you in these >> post that you're free to change and use for your own personal use. >> >>> >> >>> So, telling him things, he probably already knows, in hopes of making >> yourself looks good. Actually make you look like a "know it all". e.g. it >> doesn't make you look good. >> >>> >> >>> SO perhaps you should realize that Gerald is probably well aware of >> what you're trying to discuss here, but is unwilling to change for various >> reasons. Reason, that you, I, or the next person do not need to understand. >> Because we can change to designs to our own liking if we so wish. >> >>> >> >>> On Mon, Jul 4, 2016 at 1:55 PM, Gerald Coley <ger...@beagleboard.org >> <mailto:ger...@beagleboard.org>> wrote: >> >>> Thank you for your feedback. >> >>> >> >>> Gerald >> >>> >> >>> On Mon, Jul 4, 2016 at 3:18 PM, <kzsoltkzs...@gmail.com <mailto: >> kzsoltkzs...@gmail.com>> wrote: >> >>> First of all making changes on design "tomorrow" is irresponsible, so >> I never request it. But good to know where is some "leak" in design. For >> example it is help to make workaround. >> >>> >> >>> "TI did not write that specification" >> >>> No, but use it in all reference design. See TI TPS20x1 PDS application >> information. See for example TPS2051 docu Fig 33. >> >>> >> >>> "If you put the CAP after the switch then ..." >> >>> Then why CAP placed OUT of PDS in all TI application information? >> >>> Because PDS has soft start feature which prevent overload IN (BBB SYS >> power rail). See for example TPS2051 docu Fig 4 and 8. >> >>> Fig 8 is perfect draw for this. The soft start feature limit charge of >> 100uF to 0,5A, therefore current never exceed USB1 and 2 current limit, >> therefore no dip on IN. >> >>> This is one main function of PDS. >> >>> >> >>> "I did not design the board for your application" >> >>> It is not required. But during research work to specify our problem I >> found many topic where users discover mysterious problems with power >> supply, and try to found a right one for BBB. This can be originated from >> startup current peak. >> >>> >> >>> >> >>> -- >> >>> For more options, visit http://beagleboard.org/discuss < >> http://beagleboard.org/discuss> >> >>> --- >> >>> You received this message because you are subscribed to the Google >> Groups "BeagleBoard" group. >> >>> To unsubscribe from this group and stop receiving emails from it, send >> an email to beagleboard+unsubscr...@googlegroups.com<mailto: >> beagleboard+unsubscr...@googlegroups.com>. >> >>> To view this discussion on the web visit >> https://groups.google.com/d/msgid/beagleboard/b974f98a-0cff-4380-af1f-9ce5db9e199f%40googlegroups.com >> < >> https://groups.google.com/d/msgid/beagleboard/b974f98a-0cff-4380-af1f-9ce5db9e199f%40googlegroups.com?utm_medium=email&utm_source=footer >> >. >> >>> >> >>> For more options, visit https://groups.google.com/d/optout < >> https://groups.google.com/d/optout>. >> >>> >> >>> >> >>> >> >>> -- >> >>> Gerald >> >>> >> >>> ger...@beagleboard.org <mailto:ger...@beagleboard.org> >> >>> http://beagleboard.org/ <http://beagleboard.org/> >> >>> gcol...@emprodesign.com <mailto:gcol...@emprodesign.com> >> >>> >> >>> >> >>> -- >> >>> For more options, visit http://beagleboard.org/discuss < >> http://beagleboard.org/discuss> >> >>> --- >> >>> You received this message because you are subscribed to the Google >> Groups "BeagleBoard" group. >> >>> To unsubscribe from this group and stop receiving emails from it, send >> an email to beagleboard+unsubscr...@googlegroups.com<mailto: >> beagleboard+unsubscr...@googlegroups.com>. >> >>> To view this discussion on the web visit >> https://groups.google.com/d/msgid/beagleboard/CAHK_S%2BcAH_U%3DVtJmLq62wrVPmRg8%2Bn27YjWM_oeorZezSTKorQ%40mail.gmail.com >> < >> https://groups.google.com/d/msgid/beagleboard/CAHK_S%2BcAH_U%3DVtJmLq62wrVPmRg8%2Bn27YjWM_oeorZezSTKorQ%40mail.gmail.com?utm_medium=email&utm_source=footer >> >. >> >>> >> >>> For more options, visit https://groups.google.com/d/optout < >> https://groups.google.com/d/optout>. >> >>> >> >>> >> >>> -- >> >>> For more options, visit http://beagleboard.org/discuss < >> http://beagleboard.org/discuss> >> >>> --- >> >>> You received this message because you are subscribed to the Google >> Groups "BeagleBoard" group. >> >>> To unsubscribe from this group and stop receiving emails from it, send >> an email to beagleboard+unsubscr...@googlegroups.com<mailto: >> beagleboard+unsubscr...@googlegroups.com>. >> >>> To view this discussion on the web visit >> https://groups.google.com/d/msgid/beagleboard/CALHSORo-TL2x_vUEni%2B-daiSEQXxLUU_N5p%2BEh%2Bt6tzpuuPT0g%40mail.gmail.com >> < >> https://groups.google.com/d/msgid/beagleboard/CALHSORo-TL2x_vUEni%2B-daiSEQXxLUU_N5p%2BEh%2Bt6tzpuuPT0g%40mail.gmail.com?utm_medium=email&utm_source=footer >> >. >> >>> For more options, visit https://groups.google.com/d/optout < >> https://groups.google.com/d/optout>. >> > >> > -- >> > For more options, visit http://beagleboard.org/discuss >> > --- >> > You received this message because you are subscribed to the Google >> Groups "BeagleBoard" group. >> > To unsubscribe from this group and stop receiving emails from it, send >> an email to beagleboard+unsubscr...@googlegroups.com. >> > To view this discussion on the web visit >> https://groups.google.com/d/msgid/beagleboard/cjolnb1s1bddugkd1v6c4jeqm1a0mhmvhh%404ax.com >> . >> > For more options, visit https://groups.google.com/d/optout. >> >> -- >> For more options, visit http://beagleboard.org/discuss >> --- >> You received this message because you are subscribed to the Google Groups >> "BeagleBoard" group. >> To unsubscribe from this group and stop receiving emails from it, send an >> email to beagleboard+unsubscr...@googlegroups.com. >> To view this discussion on the web visit >> https://groups.google.com/d/msgid/beagleboard/70E6C922-DEB1-451D-A72C-AC4C2EA2DF06%40gmail.com >> . >> For more options, visit https://groups.google.com/d/optout. >> > > > >-- >Gerald > >ger...@beagleboard.org >http://beagleboard.org/ >gcol...@emprodesign.com -- For more options, visit http://beagleboard.org/discuss --- You received this message because you are subscribed to the Google Groups "BeagleBoard" group. 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