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Everything Else » Define PUOE

June 13, 2011
by JoyceChee
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can anyone explain what is Pull-Up Override Enabled (PUOE)?

June 13, 2011
by bretm
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For general-purpose I/O pins, the pull-up state is controlled by the PORTxn bit when the pin is configured for input (DDRxn = 0), except that all pull-ups are disabled when bit PUD of MCUCR is set.

PUOE turns on an internal override mechanism. Most pins have an alternate function, e.g. if you enable serial I/O it makes the TX and RX pins unusable as general-purpose I/O. The PUOE signal disables the normal pull-up logic and hands it over to PUOV, which is controlled by the alternate function of the pin.

PUOE and PUOV are just internal circuitry, not registers that you can access.

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