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Using PU.1 & PU.0 as GPIO

We're trying to use PU.1 and PU.0 as GPIO on a MSP430F6438IPZ.  I have unlocked the LDOKEYPID register, and regardless of the value that I wrote to PUCTL, the pins will not toggle.  I have PUIPE set and based on the logical layout for that port, this should be OK, but I have tried it both ways.  Any suggestions greatly appreciated.

LDOKEYPID = 0x9628;
PUCTL |= PUOPE;
PUCTL |= PUIPE;
PUCTL |= PUOUT1 | PUOUT0;

Whitt Batcheler

  • I'm not sure about the 6438 but on a 5310 that I used the Port U pins are powered by VUSB rail.

    38.2.1.3 Port U Control
    When PUSEL is cleared, the Port U pins (PU.0/PU.1) function as general-purpose, high-current I/O pins.
    These pins can only be configured together as either both inputs or both outputs. Port U is supplied by the
    VUSB rail. If the 3.3-V LDO is not being used in the system (disabled), the VUSB pin can be supplied
    externally.

    Hope this helps.

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