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Can P30 drive high? — Parallax Forums

Can P30 drive high?

Lee MarshallLee Marshall Posts: 106
edited 2007-11-01 04:19 in Propeller 1
Why is there a pullup resistor on P30(TX to PC) on the propstick? is this pin "open drain"?
i fixed the intermittent "propeller lost" fault on my dev board(homemade) by adding a pullup resistor. i can only assume that this is due to the pins output driver being open drain, if this is so, why is it?

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I hear and I forget. I see and I remember. I do and I understand
-Confucius

Comments

  • Peter JakackiPeter Jakacki Posts: 10,193
    edited 2007-11-01 03:51
    If the fault is intermittent isn't it a little early to say that it's fixed? (Murphy's law)

    P30 like all the port pins are programmable and these pins are all inputs (floating) when the prop is reset which can easily generate false tx data without a pullup.

    *Peter*
  • Lee MarshallLee Marshall Posts: 106
    edited 2007-11-01 04:19
    when i say intermittent, i mean i would have to attempt a transfer a number of times before it would be successful, without physically touching the board. as soon as i added the resistor, the problem ceased, and has never returned.

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    I hear and I forget. I see and I remember. I do and I understand
    -Confucius
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