Parallax P2 Eval Board

1235710

Comments

  • jmgjmg Posts: 14,029
    Rayman wrote: »
    That's a nice looking heatsink. I wonder how effective it would be on top...

    Might bump into all those pins on top ? This is a large PCB with a lot of unused area, but leaves not much room for top-cooling.
    Given the die mounts directly onto the bottom copper pad, cooling-under will be more effective.

    An alternative design approach would be to place the P2 on the bottom side, and all tall parts on the top-side.
  • Yeah, that is the problem with having all them testers down under.

    Now we have to mount the P2D2 module upside down to mount the heat-sink where it belongs to...

    Mike
    I am just another Code Monkey.
    A determined coder can write COBOL programs in any language. -- Author unknown.
    Press any key to continue, any other key to quit

    The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this post are to be interpreted as described in RFC 2119.
  • Centre of gravity is better with heatsink below. And air cooling also works better drawing from below. It'll be a racer. :)

    I love the whooshing sound of deadlines as they fly by.
  • evanh wrote: »
    Centre of gravity is better with heatsink below. And air cooling also works better drawing from below. It'll be a racer. :)

    We added two holes for a 5 volt fan connector. The header can be mounted on the top or the bottom of the board.
  • jmgjmg Posts: 14,029
    cgracey wrote: »
    evanh wrote: »
    Centre of gravity is better with heatsink below. And air cooling also works better drawing from below. It'll be a racer. :)

    We added two holes for a 5 volt fan connector. The header can be mounted on the top or the bottom of the board.

    and mounting holes for the fan itself ? ;) (northbridge fan sets seems common and cheap, tho I think 12V)
    The PCB images seem to not show any Vias - is that just some setting in the render, as I guess you are not doing buried/blind vias ?

    Vias may affect the choices for direct cooling, needing some insulation to the heatsink, or some mechanical step that contacts inner GND only. (perhaps a reflow copper standoff?).
    I see Raspberry Pi sets include a 12x12mm copper shim - with care, I think you can route P2 to have a 12mm clear GND square ?
  • The whole bottom of the PCB is GND. The fan would best mount underneath, like Evanh said. That way, you get the best cooling and don't obscure the top side of the board where are the headers are.
  • jmgjmg Posts: 14,029
    cgracey wrote: »
    The whole bottom of the PCB is GND. The fan would best mount underneath, like Evanh said. That way, you get the best cooling and don't obscure the top side of the board where are the headers are.

    Are you thinking of just a fan - I suppose that could work, with modest standoffs to allow air-paths ? Any fan will give serious amounts of cooling.
    I was thinking about (almost) direct thermal contact, with a heatsink, but here vias could matter.
    Perhaps anodize and solder mask is enough, or a thin good thermally insulator. An alternative would be a small standoff in the centre of the heatsink, a la copper shim.

    or maybe something like Digikey PH3N-50.8-12.7-0.062-1A = Thin sticky Tape+Copper 50.8X12.07X0.062MM 20c/100
    or these ? https://www.digikey.com/en/product-highlight/3/3m/8810-thermally-conductive-adhesive-transfer-tapes

    3M10315-ND Thermal Pad White 4.57m x 12.70mm Rectangular Adhesive - Both Sides - expensive at $28/roll, but that's ~ 7c/12mm cut pad

    An appeal of the good double sided tape, is you can use almost any flat-surface heatsink.
  • Thanks, Jmg. For 180MHz, no heatsink should be required, but if one wanted to overclock indefinitely, maybe they could use those thermally-conductive adhesive pads with a Peltier and a fan to really keep the temp down.
  • So in my country, do I need a refrigerator to use the P2?

    Please keep calm and the temperature low, and expect more speed with the P3.
  • So in my country, do I need a refrigerator to use the P2?

    Please keep calm and the temperature low, and expect more speed with the P3.

    These heat concerns are overblown. Yes, if you want to run indefinitely at 360MHz, you will need some fan, most likely. At 180MHz, it just gets rather warm.
  • I leave my unit running indefinitely at 300MHz or more and in ambient temperatures of 32'C lately. However it uses a small 25mm 5V fan mounted on the reverse side of the P2D2 and this keeps the temperature down well in the 30's.

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  • I have been running with ambient 33C and 180MHz without a fan/heatsink. Its fine :smiley:

    There is way too much emphasis being placed on cooling the chip!!! Only us overclockers are going to be bothered.
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  • cgracey wrote: »
    KaylaMarie wrote: »
    Soooo... Pricing and availability on these? I want one!!!

    Not sure, yet. It's two weeks away. Pricing is going to be $100-$200, probably. Maybe right in the middle.

    Chip, I don't think those prices are too crazy for what the cost of the first run chips are and what is included.

    Once production chips come, hopefully Parallax or a 3rd party will come to market with much less expensive boards.

    I'm probably not a customer that will dive into hand soldering a P2 to my own design, but will pay a reasonable price for something like a P2 in something like a PropMini or Propeller FLiP to put into a project.
  • It is done. This 3D rendering makes the text look less aligned than it actually is.


    2018-11-07%2013_08_02-3D%20Preview.png
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  • Cool! Have the chips come in yet?
  • David Betz wrote: »
    Cool! Have the chips come in yet?

    No. They will get here before the PCB's do, though.
  • OK.... who is going to be the first for 3D print or laser cut enclosure?
  • I will definitely be 3D printing a custom mount for it with & without a fan.
    That design could easily become general purpose.
    I'll be modelling/printing it once I have board & fan in hand.

    j
  • I'm trying to get the dimensions as we speak. I will post if I can.
  • I assume that no fan is needed if I don't intend to overclock the P2. Is that correct? If that's the case, some rubber feet on the bottom is all I'll need to start.
  • David Betz,
    You won't need any active or passive cooling for 180Mhz. You might want some minor cooling for 250Mhz, and definitely want some decent cooling if you plan to push it to 300+Mhz
  • Roy Eltham wrote: »
    David Betz,
    You won't need any active or passive cooling for 180Mhz. You might want some minor cooling for 250Mhz, and definitely want some decent cooling if you plan to push it to 300+Mhz
    Thanks! That's what I thought. I'm likely to be running at 180mhz since all I'll be using it for is testing tools.

  • where is P2-USB connected to?

    Mike
    I am just another Code Monkey.
    A determined coder can write COBOL programs in any language. -- Author unknown.
    Press any key to continue, any other key to quit

    The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this post are to be interpreted as described in RFC 2119.
  • cgraceycgracey Posts: 11,789
    edited 2018-11-07 - 18:19:14
    msrobots wrote: »
    where is P2-USB connected to?

    Mike

    P56 and P57. I need to confirm the order of DP and DM.
  • jmgjmg Posts: 14,029
    cgracey wrote: »
    It is done. This 3D rendering makes the text look less aligned than it actually is.
    I do not see provision for Clipped Sine Oscillator ? ( A simple AC coupling cap to X1 is all that is needed, as done in P2D2)
    I thought you selected a TCXO as the default Oscillator ? there is minimal price impact, and it shows off P2 capabilities nicely.

    Is there a SCH for this anywhere ?
  • msrobots,
    I believe that is the power input for the board. Not sure if the data lines are connected or not?
  • could you also squeeze in two LEDs for RX and TX like on the PC-USB side? Not really important but it disturbs the symmetry...

    Mike
    I am just another Code Monkey.
    A determined coder can write COBOL programs in any language. -- Author unknown.
    Press any key to continue, any other key to quit

    The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this post are to be interpreted as described in RFC 2119.
  • msrobots wrote: »
    could you also squeeze in two LEDs for RX and TX like on the PC-USB side? Not really important but it disturbs the symmetry...

    Mike

    They are there. Upper right.
  • jmgjmg Posts: 14,029
    msrobots wrote: »
    could you also squeeze in two LEDs for RX and TX like on the PC-USB side? Not really important but it disturbs the symmetry...
    Those TX & RX are from the FTDI part, there is no equivalent FTDI on the other USB, so no TX/RX exist there - that package merely looks like a FTDI (caught me out too..)

  • cgraceycgracey Posts: 11,789
    edited 2018-11-07 - 18:40:11
    jmg wrote: »
    cgracey wrote: »
    It is done. This 3D rendering makes the text look less aligned than it actually is.
    I do not see provision for Clipped Sine Oscillator ? ( A simple AC coupling cap to X1 is all that is needed, as done in P2D2)
    I thought you selected a TCXO as the default Oscillator ? there is minimal price impact, and it shows off P2 capabilities nicely.

    Is there a SCH for this anywhere ?

    I looked into it, but we do, at least, need a crystal in place. The problem is that we cannot input a clock into XI without driving XO. So, the crystal's presence precludes the use of a clipped-sign oscillator feeding into Xi.
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