32.3.1.1 Over Voltage Tolerance
Over voltage capability is available for most pins. If available, it allows the pin to be used at the minimum of IOVDD + 2V and 5.5V (for
5V tolerant pads). The data sheet specifies which pins can be used as 5V tolerant pins. Default over voltage is enabled for each pin
supporting that feature. Over voltage tolerance (OVT) can be disabled on a per pin basis. The over voltage tolerance feature applied to
the selected pins is configured in the GPIO_Px_OVTDIS register. Disabling the over voltage tolerance for a pin will provide less distor-
tion on that pin, which is useful when the pin is used as analog input.
Note:
The VDAC (and OPAMPs) can drive outputs above IOVDD and therefore the involved pads typically require OVT to be be enabled.
32.3.1.2 Alternate Port Control
The Alternate Port Control allows for additional flexibilty of port level settings. A user may setup two different port configurations (normal
and alternate modes) and select which is applied on a pin by pin bases. For example you may configure half of port A to use the low
drive strength setting (normal mode) while the other half uses high drive strength (alternate mode).
Alternate port control is enabled when MODEn is set to any of the ALT enumerated modes (ie. PUSHPULLALT). When MODEn is an
alternate mode, the pin uses the alternate port control values specified in the DINDISALT,SLEWRATEALT, and DRIVESTRENGTHALT
fields in GPIO_Px_CTRL. In all other modes, the port control values are used from the DINDIS,SLEWRATE, and DRIVESTRENGTH
fields in GPIO_Px_CTRL.
32.3.1.3 Drive Strength
The drive strength can be applied to pins on a port-by-port basis. The drive strength applied to pins configured using normal MODEn
settings can be controlled using the DRIVESTRENGTH field in GPIO_Px_CTRL. The drive strength applied to pins configured using
alternate MODEn settings can be controlled using the DRIVESTRENGTHALT field.
32.3.1.4 Slewrate
The slewrate can be applied to pins on a port-by-port basis. The slewrate applied to pins configured using normal MODEn settings can
be controlled using the SLEWRATE fields in GPIO_Px_CTRL. The slewrate applied to pins configured using the alternate MODEn set-
tings can be controlled using the SLEWRATEALT field.
32.3.1.5 Input Disable
The pin inputs can be disabled on a port-by-port basis. The input of pins configured using the normal MODEn settings can be disabled
by setting DINDIS in GPIO_Px_CTRL. The input of pins configured using the alternate MODEn settings can be disabled by setting DIN-
DISALT.
32.3.1.6 Configuration Lock
GPIO_Px_MODEL, GPIO_Px_MODEH, GPIO_Px_CTRL, GPIO_Px_PINLOCKN, GPIO_Px_OVTDIS, GPIO_EXTIPSELL, GPIO_EX-
TIPSELH, GPIO_EXTIPINSELL, GPIO_EXTIPINSELH, GPIO_INSENSE, GPIO_ROUTEPEN, and GPIO_ROUTELOC0 can be locked
by writing any value other than 0xA534 to GPIO_LOCK. Writing the value 0xA534 to the GPIOx_LOCK register unlocks the configura-
tion registers.
In addition to configuration lock, GPIO_Px_MODEL, GPIO_Px_MODEH, GPIO_Px_DOUT, GPIO_Px_DOUTTGL, and GPIO_Px_OVT-
DIS can be locked individually for each pin by clearing the corresponding bit in GPIO_Px_PINLOCKN. When a bit in the GPIO_Px_PIN-
LOCKN register is cleared, it will stay cleared until reset.
Reference Manual
GPIO - General Purpose Input/Output
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