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Will a PINMODE register in lpc2468 affect the status of an input pin i.e can we enable

an internal pull up for an input pin,or it is only possible for output pins.

Eljay
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1 Answers1

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Pull-up and pull-down apply to I/O used as input, not output. Inputs shouldn't remain floating, so you either

  1. drive them with a push-pull output to a logical low or high level
  2. use external pull-up or pull-down
  3. use internal pull-up or pull-down

Pull-up/pull-down will set the input to a valid level if it would otherwise be floating. The second and third option are normally used with either open drain outputs (usually with pull-ups) or with switches/pushbuttons.

Remember that the datasheet will in general only give you device-specific information. Data which is common to all members of a microcontroller family can be found in that family's user guide.

Further reading
LPC24xx User Guide
LPC2468 Datasheet

stevenvh
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