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Quickstart board (Rev. A) - Damaged USB connector — Parallax Forums

Quickstart board (Rev. A) - Damaged USB connector

wmosscropwmosscrop Posts: 409
in Propeller 1
Well, I managed to break one of the internal pins (apparently one of the data pins) on the USB connector. Merry Christmas to me :(

I broke it in a way that apparently caused it to short to either +5V or ground within the connector, possibly damaging the FTDI chip or other circuitry. I've removed the offending pin but still have an issue.

I (of course) can no longer program the board via USB. I can program it via pins 30 & 31 (RS-232 to serial adapter circuit)--but only if power is supplied to the USB port.

This is a bit of a pain since this board is on my robot, so I have to connect and disconnect 2 connectors every time I want to reprogram the robot. Not to mention that sometimes disconnecting the USB plug causes a reset, so I generally have to store the new program to EEPROM rather than just RAM.

In the documentation for the board (Rev. A) it states "The USB circuitry, including U3 and U4, is powered from the USB bus, so when there is no USB connection present, the unpowered buffer's inputs float, leaving P30 available for other uses". Rev. B boards also do the same for P31.

So somehow I've damaged the board in a way that USB power is (apparently) required for pin 30 (and maybe 31) to work.

I'm not sure if the USB plug will take many more connect-and-disconnect cycles, so I have an idea to wire up a USB plug with just ground and 5V and power it from the robot's onboard power supply, leaving it connected all of the time.

I'm assuming that this won't cause any issues, but if anyone knows of a reason not to try this, please let me know.

And yes, I'm cheap, I know I could just replace the board.

Thanks,

Walter

Comments

  • kwinnkwinn Posts: 8,697
    If the USB connector and chip is damaged why not add a 4 pin connector and wire it up so you can use a prop plug or other usb-serial adapter for programming?
  • lardomlardom Posts: 1,659
    This may not apply but I power my Quickstart boards with 4 AA cells by a 2-pin connector from a battery pack. (-) to pin 38 and (+) to pin 39.
    And I have 3 boards. One is fried.
  • kwinnkwinn Posts: 8,697
    lardom wrote: »
    This may not apply but I power my Quickstart boards with 4 AA cells by a 2-pin connector from a battery pack. (-) to pin 38 and (+) to pin 39.
    And I have 3 boards. One is fried.

    Not surprising. The surprise is that only one board is fried. Pin 39 is the +3.3V connection to the board and you are putting 4.8 to 6V in depending on the type of battery. The +Vin should be connected to pin 40 (Vin), the input to the on board 3.3V regulator.

  • lardomlardom Posts: 1,659
    Kwinn, I fried that board by trying to power it through the VSS/VDD header. I'm doing wireless tests and using 6V battery packs on both Quickstarts with no problems.
    I first tried modifying a micro USB connector. That didn't work.
  • kwinnkwinn Posts: 8,697
    lardom wrote: »
    Kwinn, I fried that board by trying to power it through the VSS/VDD header. I'm doing wireless tests and using 6V battery packs on both Quickstarts with no problems.
    I first tried modifying a micro USB connector. That didn't work.

    Well I am surprised they're not toast. If your 6V battery pack is connected directly to pins 38 & 39 of the 40 pin header as you posted the propeller chip is running on 6 volts. Is it a miracle or could it be connected somewhere else?
  • Duane DegnDuane Degn Posts: 10,588
    I'm not sure how you're numbering the pins but pin #39 is Vss. Pin #40 is Vin (often about 5V). Pin #38 is 3.3V.
  • Duane DegnDuane Degn Posts: 10,588
    Walter, if you want to send me the board, I'll replace the USB connector (if you think it would help).
  • Ken GraceyKen Gracey Posts: 7,392
    I'd be happy to replace this board for you, Walter. Just drop me a message with your shipping address kgracey@parallax.com and we'll put this problem in the rear view mirror.

    Ken Gracey
  • lardomlardom Posts: 1,659
    kwinn wrote: »
    lardom wrote: »
    Kwinn, I fried that board by trying to power it through the VSS/VDD header. I'm doing wireless tests and using 6V battery packs on both Quickstarts with no problems.
    I first tried modifying a micro USB connector. That didn't work.

    Well I am surprised they're not toast. If your 6V battery pack is connected directly to pins 38 & 39 of the 40 pin header as you posted the propeller chip is running on 6 volts. Is it a miracle or could it be connected somewhere else?

    I could mistaken about how I numbered the pins. With the pin header at the top I'm using the two pins on the right.
  • lardomlardom Posts: 1,659
    edited 2015-12-30 18:22
    Duane Degn wrote: »
    I'm not sure how you're numbering the pins but pin #39 is Vss. Pin #40 is Vin (often about 5V). Pin #38 is 3.3V.

    That sounds right. I should probably order a label that clears it up for me.
  • PublisonPublison Posts: 12,366
    edited 2015-12-30 18:34
    lardom wrote: »
    Duane Degn wrote: »
    I'm not sure how you're numbering the pins but pin #39 is Vss. Pin #40 is Vin (often about 5V). Pin #38 is 3.3V.

    That sounds right. I should probably order a label that clears it up for me.
    https://www.parallax.com/product/721-00017





  • lardomlardom Posts: 1,659
    Publison, I copied the jpg to a folder on my desktop. I now see where it says '39' and '40'.
    I'll still order a label because it is tedious to have to use a piece of wire whenever I want to identify a pin.
  • Duane DegnDuane Degn Posts: 10,588
    If you have a Brother label maker, you could print a set.

    attachment.php?attachmentid=82231&d=1308241428

    I've attached the Brother label file to this post.
  • lardomlardom Posts: 1,659
    edited 2015-12-30 22:57
    Duane Degn, that's a great idea. That would also work for the P8X32A.
  • PublisonPublison Posts: 12,366
    edited 2015-12-31 00:43
    lardom wrote: »
    Duane Degn, that's a great idea. That would also work for the P8X32A.
    Like this: :)


    https://www.parallax.com/product/120-00003

  • wmosscropwmosscrop Posts: 409
    Everyone -

    My idea (to power the USB port) works fine.

    kwinn -

    Your idea to wire up a connector (for a prop plug) is close to what I implemented. For some reason the prop plug won't work with my fix, but the RS-232 to serial adapter works.

    Duane -

    Thanks for the kind offer, but I have an acceptable workaround (at least until I break something else...) I thought about replacing the connector myself but I know better than to try to fix something this small.

    Ken -

    Thank you also for your very kind offer, but I will pass. I do appreciate Parallax standing behind their products. The issue (with the broken connector) was entirely my fault. The board still works for my needs; in fact, it's now easier to program via the header instead of the USB port. If it does fail in the future I have no issues with purchasing another board.

    My lesson learned is to mount boards so that the connectors can be mated properly, not at an angle, and not under physical stress.

    Thanks,

    Walter
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