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Using Pull-up resistors with the prop ? — Parallax Forums

Using Pull-up resistors with the prop ?

JMLStamp2pJMLStamp2p Posts: 259
edited 2008-04-05 17:03 in Propeller 1
Hello All,
I will be monitoring three inputs on my Prop Proto board on pins 4,5 & 6.
These pins will be attached to 3 limit switch's that are normally open. Should I use pull-up resistors from 6.6K - 10K, I have been looking but do not see anywhere that the Prop has internal resistors for this purpose, Is this correct?
JMLStamp2p
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Comments

  • Mike GreenMike Green Posts: 23,101
    edited 2008-04-04 19:03
    The Prop has no internal pullup or pulldown resistors on its I/O pins.
  • JMLStamp2pJMLStamp2p Posts: 259
    edited 2008-04-04 19:12
    Mike,
    What size pull-up would you normally use yourself for this ?
  • Mike GreenMike Green Posts: 23,101
    edited 2008-04-04 19:17
    10K usually works well. For switches in electrically noisy environments or where the switch contacts might be dirty, I'd use a lower resistance, maybe as little as 1K, to provide more current through the circuit and across the contacts. Where the contacts are gold or the switch is sealed from the environment and the distance to the switch is relatively short (inches to a foot or so) and electrically quiet, I'd use 10K or even higher to as much as 100K, particularly if running off batteries.
  • JMLStamp2pJMLStamp2p Posts: 259
    edited 2008-04-04 19:19
    Thank You Mike.
  • JMLStamp2pJMLStamp2p Posts: 259
    edited 2008-04-05 17:03
    Installed 1K's and they work fine. I am installing them in an harsh invironment.
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