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Piggyback - dangerous or benign — Parallax Forums

Piggyback - dangerous or benign

HumanoidoHumanoido Posts: 5,770
edited 2010-02-28 17:50 in Propeller 1
Consider placing one prop chip on top of another
where all the pins connect.

(take a look at the Propalyzer to see a piggyback
arrangement)

http://forums.parallax.com/showthread.php?p=788315

However, there are no protection resistors on the
I/O pins. There may be a condition when the output
pin is high and the input pin is low and smoke will
result. Is there a way to compensate this for safety
reasons?

Thank you for your replies.

humanoido

Post Edited (humanoido) : 2/21/2010 5:46:31 PM GMT

Comments

  • Mike HuseltonMike Huselton Posts: 746
    edited 2010-02-21 17:43
    See my post to you about three dimensional stacking to avoid this problem.

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    JMH
  • jazzedjazzed Posts: 11,803
    edited 2010-02-21 17:48
    humanoido said...
    Consider placing one prop chip on top of another
    where all the pins connect.

    (take a look at the Propalyzer to see a piggyback
    arrangement)

    http://forums.parallax.com/showthread.php?p=788315

    However, there are no protection resistors on the
    I/O pins. There may be a condition when the output
    pin is high and the input pin is low and smoke will
    result. Is there a way to compensate this?

    Thank you for your replies.

    humanoido
    Propalyzer pins other than serial tx which is not connected are always inputs. I prefer and recommend using a separate oscillator though. There is no chance of damage with Propalyzer code as is ... you have to think about what your code will do however ... YMMV.
    Good Luck.
  • HumanoidoHumanoido Posts: 5,770
    edited 2010-02-21 17:48
    http://forums.parallax.com/showthread.php?p=883051
    Mike Huselton said...
    Also, think three-dimensional stacking with increasingly wider offsets between layers.
    Mike, can you elaborate on this?

    humanoido
  • Graham StablerGraham Stabler Posts: 2,510
    edited 2010-02-21 18:19
    H,

    Assuming you mean to solder them in to stacks then you could probably bend the legs out flat, cut them a little short and solder small through hole resistors on each IO pin. Then make a PCB (or use veroboard) to go on each side of the block of propellers you have created, this would form the common between pins. The current being limited between any two pins by two resistors. That said if you make one pin high and all other pins low you may still have issues.

    Graham
  • jazzedjazzed Posts: 11,803
    edited 2010-02-21 18:29
    Without series resistors between pins, it's best to keep a close tab on the temperature of the devices. If they get warm, you definitely have a problem. Just a SMALL amount of time with outputs driving each other in opposite states won't damage your propeller (been there, done that). Prolonged "crowbarring" will probably kill the IOs or more permanently though.
  • mikedivmikediv Posts: 825
    edited 2010-02-21 20:19
    I have a question though if you stack the props so each pin is touching example I/O pins what good would it be??? wouldn't it be better to have all the I/O lines separate or am I missing somehting? thanks
  • HumanoidoHumanoido Posts: 5,770
    edited 2010-02-21 20:50
    Mikediv said...
    I have a question though if you stack the props so each pin is touching example I/O pins what good would it be??? wouldn't it be better to have all the I/O lines separate or am I missing somehting? thanks
    In the design, there is minimal space so stacking is a consideration, and at the same time there's a small percentage of computational props. You need the pins to grip the other pins to make the stack stick. If their pins are kept as inputs, it's feasible for each to accomplish their purpose. That's the idea. But at this time it seems there is no solid way to overcome the accidental danger of shorts using software only. I'm hoping for more ideas. If we can get this idea working, we only need to stack one chip on top of another, or make several chip stacks, without boards, wires, sockets or soldering.

    humanoido

    Post Edited (humanoido) : 2/21/2010 9:06:52 PM GMT
  • Clock LoopClock Loop Posts: 2,069
    edited 2010-02-22 13:14
    What you need, and the community, is :

    SEMICONDUCTOR SOLDER/GLUE.

    and

    CARBON SOLDER/GLUE.

    Once you figure out where to get these things, let me know.


    I'd like a "dope your own silicon" kit myself.

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    TERMS OF USE: MIT License

    "Permission is hereby granted, free of charge, to any pers...........................
    ..............................OMITTED FOR FORUM...............................................
    .................. OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. "

    The dsp/fpga king is dead, long live the prop.
  • HumanoidoHumanoido Posts: 5,770
    edited 2010-02-22 16:31
    Clock Loop said...
    What you need, and the community, is :
    SEMICONDUCTOR SOLDER/GLUE.
    and
    CARBON SOLDER/GLUE.
    What is it? Several companies make various forms of liquid solder for joining metals with a conductive glue. Google liquid solder. Though the actual "trade name" liquid solder now represents ordinary glue. However, I don't see how that will protect the pins unless we can paint on some resistor material between the pins representing 220 ohms or more.

    humanoido

    Post Edited (humanoido) : 2/22/2010 4:36:31 PM GMT
  • mctriviamctrivia Posts: 3,772
    edited 2010-02-22 19:46
    semi conductive solder if it exists would allow you to have a resistance between pins. however since the pins will likely be touching at some point you will still get almost 0 ohms resistance.

    how about this for a space saver? 7.48x0.9" only 0.25" thick fully populated. All 8 props are off a single clock source and eeprom booted in series or they can be broken apart into 8 seperate props with crystal and individual eeproms.

    attachment.php?attachmentid=68012

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    24 bit LCD Breakout Board now in. $24.99 has backlight driver and touch sensitive decoder.

    If you have not already. Add yourself to the prophead map
    2253 x 294 - 16K
  • BigFootBigFoot Posts: 259
    edited 2010-02-22 20:25
    Why fool around with two prop chips when you could make a cube out of six of them [noparse]:)[/noparse]...

    Russ
  • mctriviamctrivia Posts: 3,772
    edited 2010-02-22 20:36
    P7,P15,P23,P31 would be unreachable

    fly wires would be needed for vdd,vss, and crystal but it would look cool.

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    24 bit LCD Breakout Board now in. $24.99 has backlight driver and touch sensitive decoder.

    If you have not already. Add yourself to the prophead map
  • HumanoidoHumanoido Posts: 5,770
    edited 2010-02-23 08:38
    BigFoot said...
    Why fool around with two prop chips when you could
    make a cube out of six of them [noparse]:)[/noparse]...Russ

    Wow!!!
    mctrivia said...
    how about this for a space saver? 7.48x0.9" only 0.25"
    thick fully populated. All 8 props are off a single clock source and eeprom booted
    in series...

    Wow!!!

    I am absolutely blown away by these two great suggestions!
    One thing is apparent, this forum has some of the greatest
    minds in the world.
  • mctriviamctrivia Posts: 3,772
    edited 2010-02-23 08:49
    i have been working on this new design for the last few days and just finished. My Goals Were:

    Cheap
    Leave all IO Free
    Multiple configurable
    Lots of Props


    I suceeded I think. Fully assembled boards would cost about $150 maybe less still working on pricing. But the PCB would only be about $15-$20 and all the parts I have used are fairly easy to hand solder.
    All IO are free. SCL, SDA are on a common bus with P31 used to triger next devices reset. When broken apart theses 3 pins are completely seperate though and there are solder points.
    The board has a brown out detection, reset button, and amplified crystal circuit on the left and 8 individual props to the right. props can be seperated into 8 seperate boards with crystals and eeproms each or kept as 1 board and utilize the common clock/eeprom. BOE circuit on each prop can be enabled or disabled on each board. though must be disabled if using as 1 single board(which is why I provided an external BOE circuit).
    8 props.

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    24 bit LCD Breakout Board now in. $24.99 has backlight driver and touch sensitive decoder.

    If you have not already. Add yourself to the prophead map
  • HumanoidoHumanoido Posts: 5,770
    edited 2010-02-23 09:01
    mctrivia: tell us more about your board design...

    1) the first section of the board has reset, crystal,
    eeprom, and what is the remaining rectangular component?

    2) What do you mean eeprom booted in series? Just one
    eeprom or one eeprom for each prop?

    3) In your opinion, regarding 8 props on the same crystal,
    what is the performance reliability?

    Thanks.
    humanoido
  • mctriviamctrivia Posts: 3,772
    edited 2010-02-23 09:08
    1) First section contains
    *clock generator(crystal, inverter, shmit triger, and filter)
    *Reset switch
    *Brown Out Detector(Resets prop if voltage drops below 2.9V)

    2) There are pads for 1 eeprom on each of the 8 prop boards but when used as 1 board only 1 is soldered on. The props boot up off the single eeprom in series 1 after the other. When boards are separated there can be a separate eeprom for each. This keeps cost down since you only need 1 eeprom for all 8 props.

    3) I am not just using a crystal to drive 8 props. but instead have implemented a crystal based clock generator. The clock generator isolates the crystal from the props keeping it acurate as well as can provide more current and cleaner wave form to the props. There would be no trouble running 8 props off 1 crystal.

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    24 bit LCD Breakout Board now in. $24.99 has backlight driver and touch sensitive decoder.

    If you have not already. Add yourself to the prophead map
  • mctriviamctrivia Posts: 3,772
    edited 2010-02-23 09:31
    maybe this is more helpful

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    24 bit LCD Breakout Board now in. $24.99 has backlight driver and touch sensitive decoder.

    If you have not already. Add yourself to the prophead map
    2838 x 350 - 670K
    top.PNG 669.6K
  • HumanoidoHumanoido Posts: 5,770
    edited 2010-02-23 10:47
    mctrivia: your work is very impressive.
    I believe you have ushered in a new era
    of multiple Propeller Chip - 44-Pin QFP
    variety - board technology.
    Congratulations!!!

    humanoido
    P8X32A-Q44-M.jpg
    Propeller Chip - 44-Pin QFP
  • HumanoidoHumanoido Posts: 5,770
    edited 2010-02-25 09:23
    Is there a prop thread about the crystal based clock generator circuit?
    I would like to take a look at the schematic and components.

    humanoido
  • HumanoidoHumanoido Posts: 5,770
    edited 2010-02-28 14:16
    mctrivia: where can I find the schematic for the 8 prop chip board?

    humanoido
  • Toby SeckshundToby Seckshund Posts: 2,027
    edited 2010-02-28 15:28
    If only half of all this had been done already, in the form of the P8X64, with all those lovely "B" pins.

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    Style and grace : Nil point
  • hinvhinv Posts: 1,255
    edited 2010-02-28 17:50
    jazzed did a stack of 5 to 8 DIP props and had communication between them, but I can't seem to find it now.
    That search facility really needs to be fixed.

    Doug
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