Parallax P2 Eval Board

2456710

Comments

  • cgraceycgracey Posts: 10,177
    edited October 26 Vote Up0Vote Down
    We plan to make lots of little add-on boards for various purposes. The point of this board is just to make the P2 functional.

    Extras that connect to the headers:

    - HDMI board
    - VGA board
    - Analog video board with RCA connectors for composite and component modes
    - USB board with four connectors
    - Analog audio I/O board

    Of those above, they are all just connectors, except the analog audio board which would have capacitor-coupled I/O, and maybe a headphone amp.
  • The AUX PWR USB jack connects its DP/DM pins to P57/P56.
  • Why not have the left hand top micro USB connect to the PC?

    Its closer to the usual P62/63 on the prop. It looks like there are some top tracks already in this area. Perhaps this is still being worked through, or are the labels wrong?

  • That 20-pin SOIC chip in the upper left corner is not a USB chip. It is an octal TTL-input-level buffer to allow P[63:56] to drive 8 LEDs without loading the actual pins.
  • cgracey wrote: »
    Jmg, you noted that those switchers look kind of complicated. What would be simpler that could supply 3A and be adjustable?

    What is your Voltage-in target range, and do you need PGood ?
  • Not sure about those diagonal connectors. They're cute, but somebody might want to put the board in an enclosure, and those make it impossible. Also, you must have mounting holes in the corners. No PCB exists in isolation. You really have to leverage the design to make use of other stuff that's already out there, like standard enclosures. So my advice would be to forget cute and make it usable.

    Very good point - does this fit into any standard enclosure ?
    No dimensions yet ? - how much would it need to morph, to fit ?

  • cgraceycgracey Posts: 10,177
    edited October 27 Vote Up0Vote Down
    jmg wrote: »
    cgracey wrote: »
    Jmg, you noted that those switchers look kind of complicated. What would be simpler that could supply 3A and be adjustable?

    What is your Voltage-in target range, and do you need PGood ?

    The input is 5 volts from the USB. We do not need a power-good indication. We would like 3 amps.
  • jmg wrote: »
    Not sure about those diagonal connectors. They're cute, but somebody might want to put the board in an enclosure, and those make it impossible. Also, you must have mounting holes in the corners. No PCB exists in isolation. You really have to leverage the design to make use of other stuff that's already out there, like standard enclosures. So my advice would be to forget cute and make it usable.

    Very good point - does this fit into any standard enclosure ?
    No dimensions yet ? - how much would it need to morph, to fit ?

    It will fit on my desk really well.
  • Looking good :smiley:

    It's a testing board, so better and complicated regulators are fine. They could be changed for a new board rev on final silicon.

    If the board can be supplied without the header pins then anyone wanting females or shrouded connectors can do that.

    Would be nice to see a jumper for a 3225 oscillator since I've discovered they are cheap too. Can be a 0R or solder bridge to either 3V3 or GND. But, it's going to be fitted anyway so it's not important.

    Flash footprint is fine. Any engineer will understand the various footprint options.

    Does need four 2.5-3.5mm mounting holes. A piece of Perspex can be mounted under, or just bolts to keep the pcb off the bench.

    I kind of like the angled pcb corners. Looks good. For an engineering sample, who is going to put it in a box???

    Other connections etc such as HDMI can be on daughter pcbs. They can then be put on different port sets. Keep the base P2 board clean, just like Peter did on P2D2.

    Chip, I hope you keep some chips for those of us who want to do our own pcbs.
    My Prop boards: P8XBlade2, RamBlade, CpuBlade, TriBlade
    Prop OS (also see Sphinx, PropDos, PropCmd, Spinix)
    Website: www.clusos.com
    Prop Tools (Index) , Emulators (Index) , ZiCog (Z80)
  • cgracey wrote: »
    It will fit on my desk really well.

    I guess that qualifies as a standard enclosure ;)

  • cgraceycgracey Posts: 10,177
    edited October 27 Vote Up0Vote Down
    jmg wrote: »
    cgracey wrote: »
    It will fit on my desk really well.

    I guess that qualifies as a standard enclosure ;)

    The enclosure is actually 15.5 by 13 by 10 - feet.

    The eval board is 3.5 by 3.5 inches.

    There is plenty of room.

    And when the door is closed, the board is secure.
  • cgracey wrote: »
    jmg wrote: »
    cgracey wrote: »
    It will fit on my desk really well.

    I guess that qualifies as a standard enclosure ;)

    The enclosure is actually 15.5 by 13 by 10 - feet.

    The eval board is 3.5 by 3.5 inches.

    There is plenty of room.

    And when the door is closed, the board is secure.

    :smiley: :wink:
    My Prop boards: P8XBlade2, RamBlade, CpuBlade, TriBlade
    Prop OS (also see Sphinx, PropDos, PropCmd, Spinix)
    Website: www.clusos.com
    Prop Tools (Index) , Emulators (Index) , ZiCog (Z80)
  • cgracey wrote: »
    jmg wrote: »
    cgracey wrote: »
    It will fit on my desk really well.

    I guess that qualifies as a standard enclosure ;)

    The enclosure is actually 15.5 by 13 by 10 - feet.

    The eval board is 3.5 by 3.5 inches.

    There is plenty of room.

    And when the door is closed, the board is secure.

    I hope your room has functional windows!
  • jmgjmg Posts: 12,446
    edited October 27 Vote Up0Vote Down
    cgracey wrote: »
    jmg wrote: »
    cgracey wrote: »
    Jmg, you noted that those switchers look kind of complicated. What would be simpler that could supply 3A and be adjustable?

    What is your Voltage-in target range, and do you need PGood ?

    The input is 5 volts from the USB. We do not need a power-good indication. We would like 3 amps.

    hmm...
    Some candidates....

    These have Sync rectifiers, so eliminate that Schottky Diode, and have PGood, which I think is important, and seems to be coming back into fashion.

    NCP1593A/B (A/B variants have a slight pinout diff, around soft start**, you can do PCB for both)

    NCP1593AMNTWG OnSemi 3A SYNC 10-DFN 3,000 $0.35/3k 4V~5.5V 0.6V 3A 1MHz -40°C ~ 85°C 10-DFN (3x3)
    FETs 90 mΩ/60 mΩ Hiccup, Soft−Start, PGood, internal compensation, no Boost C needed, 100% Duty support.

    Digikey have an eval board, so you can trial it with P2D2 = NCP1593AGEVBOS-ND

    Older tech is
    NCP3170A/B OnSemi 4.5~18V, 3A, PGood, 33c/2.5k
    FETs 100 mΩ / 29 mΩ typs at 4.5V SO8 Eval is NCP3170AGEVB
    Pluses are better VMax.
    Minus are larger package, and it needs external compensation RC, so BOM is larger.


    ** Soft start I would suggest starting with, and you can see if the SS cap is not needed on USB powering.
  • Phil Pilgrim (PhiPi)Phil Pilgrim (PhiPi) Posts: 22,057
    edited October 27 Vote Up0Vote Down
    jbg wrote:
    Very good point - does this fit into any standard enclosure ?
    No dimensions yet ? - how much would it need to morph, to fit ?

    Chip,

    My preferred type of enclosure is an open-top aluminum extrusion. Here's an example from one of my suppliers:

    http://www.lansing-enclosures.com/main/micropak/e-style/index.html

    The advantage of an enclosure like this is that the top panel and end-panels can easily be laser-cut from 1/16" acetyl copolymer (similar to Delrin, but cheaper) sheet. There are also materials that can be laser engraved to make attractive panels. I use the Rowmark product line extensively for this. Here's an example (engraves white on red):

    https://www.johnsonplastics.com/rowmark-value-series-lasermax-crimson-white-1-16-engraving-plastic

    To accommodate such an enclosure, I would recommend the following mods to your board:

    1. Rotate the the diagonal connectors to point to the ends.

    2. Make sure the USB connectors protrude about 1/16" from the ends of the board, so they poke through any end panels screwed to the ends of the extrusions.

    3. Change the headers at the ends to right-angle, so they're accessible via rectangular cutouts in the end panels. (The straight headers on the sides can be accessed through the top panel. For this reason, the headers at the ends should be the ones primarily used.)

    4. Make sure that any copper -- including ground planes -- clears the aluminum ribs forming the side slots. A 0.075" margin should be adequate.

    I still have some of Lansing's N-width extrusions and can send you a sample if it's wide enough and if you'd like to examine one. I can cut it to length for you, too. Just let me know how long ...

    -Phil
    “Perfection is achieved not when there is nothing more to add, but when there is nothing left to take away. -Antoine de Saint-Exupery
  • Beautiful board ! I hope 100 to be enough to be able to get my hands on one. And I hope everyone gets one too .... Why those voltage numbers?
  • ok, I understand .. they are pin groups.
  • The first thing I want to do to change the crystal oscillator. Don't know If I will burn the plastic switch while trying that.
  • Looks great! Where do I sign up?
  • One question. Is it possible to feed the P2 with a external clock input?
    I think I will need that. Will this board allow it?
  • jmgjmg Posts: 12,446
    edited October 27 Vote Up0Vote Down
    Ramon wrote: »
    One question. Is it possible to feed the P2 with a external clock input?
    I think I will need that. Will this board allow it?

    What external clock do you have in mind ?
    P2 allows external clock, but the PCB image above does not easily support external clock.

    (see also above request to allow choice of Xtal/Osc/Clipped Sine footprints on Osc pins, which would allow external clock, with 0603 part removal.)
    Ramon wrote: »
    .... Why those voltage numbers?
    Oh, do you mean V4855 etc ?
    It does read strangely, but it means VIO for pins 48 thru 55, in shorthand.

  • rjo__rjo__ Posts: 1,954
    edited October 27 Vote Up0Vote Down
    I understand that this board is intended for testing... and so this might not be the best idea:

    How about just leaving the headers off the bottom edge of the board...pins 16-31.
    That would allow for a variety of header types. While you are at it... those headers on the right side of the board could take a hike too. Maybe split up the production run and make some with and some without.








  • jmgjmg Posts: 12,446
    edited October 27 Vote Up0Vote Down
    rjo__ wrote: »
    I understand that this board is intended for testing... and so this might not be the best idea:

    How about just leaving the headers off the bottom of edge of the board...pins 16-31.
    That would allow for a variety of header types. While you are at it... those headers on the right side of the board could take a hike too. Maybe split up the production run and make some with and some without.

    I think the inner SMD jumper-headers** would be pre-installed, (tho that means a height impact ... hmmm.... ) and the thru-hole headers are easy enough for users to fit.

    Would anyone wanting a P2 Board not have a soldering iron ?

    ** Maybe those vertical jumpers could be right angle, to avoid the height problem. Even there, these will be rarely used.
    I've seen some nice SMD solder jumpers, done purely in artwork as (ascii art) -[>>]-, where they have paste on the NC ones and no paste on the NO ones. Zero cost, and easy to modify. - and FAR less PCB area impact.

  • Male headers are harder to screw up. I can't tell one sized pin from another slightly larger sized pin. On more than one occasion I have shoved a male pin into a female header only to destroy it. With a male header, either you have good contact or you don't... no harm done.
  • JMG,

    Bought mine at Walmart:)

    The most common question that is going to be asked is: "I want to ________________(fill in the blank). Can I do this with a P2?"
    There are only two allowed answers: 1) Yes!!!
    and
    2) NO... you will need more P2's to do that.

    I'm going to need your help soon!!!



  • My plan is to attach a flat ribbon cable with a male DIP plug onto my board, and patch it into a modified existing S-100 board which used the Propeller 1.
  • cgracey wrote: »
    jmg wrote: »
    cgracey wrote: »
    It will fit on my desk really well.

    I guess that qualifies as a standard enclosure ;)

    The enclosure is actually 15.5 by 13 by 10 - feet.

    The eval board is 3.5 by 3.5 inches.

    There is plenty of room.

    And when the door is closed, the board is secure.

    That's about the size of my new enclosure too.
  • If anyone cares, I can design a 3D printable enclosure and publish the files when the board reaches my desk.

    I'd bet that a lot of people in this forum have at least a dodgy 3D printer.
  • I can probably cobble together enclosure design for laser cutters too (I have a glowforge and have made some box designs). I might even be convinced to make some for folks here as long as it's not a crazy number.
    Not something for production, of course, but fine for keeping the board safe on your bench/desk.

    So between pedward's 3d printable one and this, we should have people here covered.
  • Not sure about those diagonal connectors. They're cute, but somebody might want to put the board in an enclosure, and those make it impossible. Also, you must have mounting holes in the corners. No PCB exists in isolation.

    I agree.


    Novel Solutions - http://www.novelsolutionsonline.com/ - Machinery Design • - • Product Development
    "Necessity is the mother of invention." - Author unknown.

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