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This QuickStart board is behaving unusually — Parallax Forums

This QuickStart board is behaving unusually

whiteoxewhiteoxe Posts: 794
edited 2014-07-28 16:38 in Propeller 1
This QuickStart board is half broken , or I've done something to it when soldering. The even pins are odd. I cant use an even pin in my code, no mater which header I inset the wire into I get no voltage. Also yesterday, just touching the pads on the quickstart made them light up, they don't seem to want to do that anymore ? I had tried to use the motor controller chip SN754410NE but the motor would not budge. I gave up. Now I know it was because I was using even numbered pins . Sorry the video is not great.

Comments

  • Duane DegnDuane Degn Posts: 10,588
    edited 2014-07-27 18:03
    Mike,

    The QuickStart has a 40 pin header and these are number from 1 to 40 but the Propeller has 32 I/O pins numbered from 0 to 31. The 40-pin header numbers don't match the I/O pin numbers. I'll find a chart and add it here.

    Edit to add:

    As see in this post, I use labels to identify which I/O pin goes where.

    attachment.php?attachmentid=82231&d=1308241428

    There are other ways people have come up with to keep track of which pin is where. The Rev. B QuickStarts have the pin ID labeled on the bottom of the board.

    40000b.png?itok=wfHlB9bY

    There's also the pinfinder.

    721-00017.png?itok=zYe0KTZx

    I know you're not the first to get the header number with the I/O number mixed up. Believe it or not, this sort of pin numbering vs I/O numbering is very common. The Raspberry Pi's GPIO pin numbers don't match the physical pin number on the header either.
  • whiteoxewhiteoxe Posts: 794
    edited 2014-07-27 21:11
    I may look foolish . its so easy to see how I got to my conclusion though, the numbers 1 and two at one end and the numbers 39 and 40 printed at the right end of jumpers. I just wish I had not wasted so much time. I see why pin 29 had me stumped as well. Thanks again Duane for taking the time to clear that up. I wish there had been some printing on the underside of my quickstart. But all I feel is happy right now !
  • GenetixGenetix Posts: 1,754
    edited 2014-07-27 22:43
    Rookie mistake, Whiteoxe.

    You can't always assume that Pin numbers match connectors. Always refer to the documentation and schematic because designers sometimes do strange things.

    When in doubt, refer to the documentation.
  • Duane DegnDuane Degn Posts: 10,588
    edited 2014-07-28 08:23
    Genetix wrote: »
    Rookie mistake, Whiteoxe.

    You can't always assume that Pin numbers match connectors. Always refer to the documentation and schematic because designers sometimes do strange things.

    When in doubt, refer to the documentation.

    The "Rookie" part applies dealing with PCBs. I've seen experienced engineers make this same mistake.

    I agree with what Genetix says about checking documentation (if available) but I saw this same mistake made over on Let's Make Robots buy professional engineers.

    It's often asked "Why would they do it that way?" when there really isn't any other way to do it. Headers start their numbering at 1 and I/O pins start their numbering at 0 which is just the beginning of the reasons why the header numbers don't match the I/O pin numbers.
  • GenetixGenetix Posts: 1,754
    edited 2014-07-28 16:38
    Engineers sometimes live in the Ivory Tower just like management.
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