An other CPU discussion. Rockchip RK3399 sounds good

Discussion in 'General Discussions' started by Askarus, Jun 7, 2018.

  1. hns

    hns Very Active Member

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    Most likely a simple 2A 5VUSB power supply with USB-A connector and a (power only) cable to convert to USB-C is the cheapest variant.
    And barrel connectors are not well defined with respect to polarity and voltage. So there is some risk zu burn the circuits by using the wrong one.
    That is why we did choose USB-C.
    Well, the idea is to use it for prototyping a new CPU board for the Pyra. That one obviously must fit into the Pyra case which gets an aluminium block above the CPU board.
    So probably the best thing is to glue a heat sink on the backside (the one you can see on the photos) at the position of the "Heat Warning" symbol which is embossed into the solder stop layer. This is where the OMAP5 is on the backside.
    4 Layers
     
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  2. Letalis Sonus

    Letalis Sonus Very Active Member

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    So... is it some kind of automotive thing or is there some kind of a quasi-standardized combination among eval boards? So far I've powered all boards with such a connector that I ran into with the very same 12V barrel connector power supply. Freescale, NXP, STM, Infineon, Renesas... okay, some of those have a fairly large input voltage range, but many expect 12V only.

    I have yet to see a device with the "wrong" polarity as well, for some reason people seem to commonly go for the logical choice for once.
     
  3. zedr0k

    zedr0k Still Fresh

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    Hi Nikolaus, will the board later be available on dragonbox-shop or goldelico-shop (or both)?
     
  4. Grench

    Grench Forum Addict!

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    Does this mean that it would be possible to create development platforms for SoC options that don't already have an available development board?

    I.e. something like the Helio X30 that looks great on paper, but there are no development boards available. With the peripheral board normalized, does that open up options?
     
  5. levi

    levi Still fresh, damnit!

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    Really? In computing terms, I think you only need 12V these days if you have to power 3.5" hdds (IIRC the 2.5" SATA power spec omits 12V, but don't quote me on that). Certainly all internal components tend to run on 3.3V or lower these days, so in my limited experience, consumer grade SBCs run on 5V from some kind of small USB connector, as is the case here.

    Edit: @Letalis Sonus
     
  6. Letalis Sonus

    Letalis Sonus Very Active Member

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    They are usually rated for the same amperage on both 5V and 12V, as far as SATA/Molex connectors go. Not sure where exactly that comes from, though.

    IDE ones were running off 5V only, but SATA ones have a normal SATA interface, which includes the full power connector with all its available voltages. Some older ones may even fail to spin up if the 3.3V rail is missing, which was deprecated with SATA v3.2. They usually do not use 12V, but the power rail is available and may still be used by some.

    Even on embedded controllers the internal logic level voltage may be as low as 1.0V, which has to be provided by external voltage regulators. It may actually require about 5 different voltage levels from external sources for all sorts of functions.

    You can't just hook a random SoC up on the power rails provided by your average SATA/Molex connector, either, try to drive an electret mic off of them and you'll immediately notice why - they need a stabilized source of power, there's all sorts of crazy distortions on the power rails of the PSU, which are simply too much for the small decoupling caps.
     
  7. levi

    levi Still fresh, damnit!

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    Yes, it's much simpler to generate lower voltages as we've had simple regulators since the 1970s I think. Going up in voltage is a little bit more involved, although you've been able to do it in silicon since the early 1980s at least. But say a nominal 5V which in reality might be more like 4.6V is easily adapted into 3.3V or 1.0V, but ramping up to 12V would need over two times the 5V source current which could potentially burn out a lot of 5V PSUs. 12V is considered relatively exotic these days in purely electronic domains, and if you need it you're best off taking it in at that voltage - you won't need as beefy power cables and PSUs at least. But if you don't need it then USB is generally more convenient to most people these days.
     
  8. Bernd

    Bernd Very Active Member

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    Sorry.
    I'm an old geezer which has more faith in barrel connector when long therm durably is needed.

    And yes.
    Center negative barrel connectors are pure evil.
    And as far I knew, USB - C is much more complex to route on the board than a conventional connectors.

    I knew that in the Pyra is no space for fancy heat sink.
    I thought of the use as a retirement place for processor boards to get a little bit extra cooling.
    There are not that many vias which guide the heat through the board to be able to mount the heat sink on the back side of the board.

    I know, this cooling-opening would be expensive and difficult to to produce.
    But isn't it allowed for an old man to dream?
     
  9. klapse

    klapse Central Scrutinizer

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    So y'all are more interested in spectre-susceptible ARM chips than i.MX8 with Cortex A53? A53 seemed fine for me, /except/ for heavy websites :/
     
  10. Gon

    Gon Member

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    That would only be a sidestep for me. It seems to have some advantages but I personally would not drop 100+ Euro on an i.MX8 "upgrade" board which is also worse in many important tasks than the OMAP5.
     
  11. hns

    hns Very Active Member

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    Well, the whole board is designed to run from 5V/2A (USB power supply). So a 12V input doesn't fit well anyways. Therefore I chose the USB-C connector.
    --- Double Post Merged, Jul 3, 2018, Original Post Date: Jul 3, 2018 ---
    The plan is to have them Built-To-Order to handle so that you can choose Ethernet or WLAN option or others.
    So it makes only sense to have them in the Goldelico shop (at least initially). Unless it becomes clear that a certain model gets let's say >100 orders.
    Maybe an e-mail request would suffice for the beginning...
    --- Double Post Merged, Jul 3, 2018 ---
    Well, we only use power through USB-C... It is not an USB-C interface. So routing on the board is no issue.
    Sure... Yes, we old men sometimes have dreams and sometimes we can make them become reality :)
     
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  12. klapse

    klapse Central Scrutinizer

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    Yeah it only upgrades opensourciness and brings OpenGL. Performancewise it looks like a downgrade afaict.
     
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  13. pmprog

    pmprog Advanced Member

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    Is there an option for a board that mimics the "mobile" option of the Pyra? ie, modem, gps, sensors?
     
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  14. CommanderB

    CommanderB Member

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    I am looking forward to the devboard! I could imagine that it is going to be quite popular due to the extensibility

    When will it be possible to order the board? Is there going to be a complete set including the CPU?

    Gesendet von meinem SM-N9005 mit Tapatalk
     
  15. OppositeDay

    OppositeDay Still Fresh

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  16. hns

    hns Very Active Member

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    You can connect a 3G/4G-stick to one of the USB ports to get modem/gps. Sensors could be connected through i2c by using breakout-boards for the sensor chips and wiring them to the contact pads on den eval board.
     
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  17. pmprog

    pmprog Advanced Member

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    Might be a dumb question, but shouldn't have any issues due to different chipsets used in whatever modem I pick?
     
  18. Nilsnsn

    Nilsnsn Member

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    Be careful if you try Nvidia boards. I carelessly powered my old Jetson TK1 with the supply from TX2 and now its dead. TK1 expects 12V and can stand something up to 14-16V, but TX1 and 2 are supplied with 19V using the same barrel connector... didn't notice that fast enough.
     
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  19. sebt3

    sebt3 homebrew player (P. & C.)

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    All drivers provide the same serial interface;)
     
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  20. Silent-Hunter

    Silent-Hunter Advanced Member

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    What about for making and receiving calls though? If someone wants to experiment with that.
     

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