Texas Instruments TM4C1294NCPDT, Datasheet

Page: 775 / 1890

Register 14: GPIO Open Drain Select (GPIOODR), offset 0x50C
The GPIOODR register is the open drain control register. Setting a bit in this register enables the
open-drain configuration of the corresponding GPIO pad. When open-drain mode is enabled, the
corresponding bit should also be set in the
GPIO Digital Enable (GPIODEN) register (see page 781).
Corresponding bits in the drive strength and slew rate control registers ( GPIODR2R , GPIODR4R ,
GPIODR8R , and GPIOSLR ) can be set to achieve the desired fall times. The GPIO acts as an input
if the corresponding bit in the GPIODIR register is cleared. If open drain is selected while the GPIO
is configured as an input, the GPIO will remain an input and the open-drain selection has no effect
until the GPIO is changed to an output.
When using the I
2
C module, in addition to configuring the data pin to open drain, the GPIO Alternate
Function Select (GPIOAFSEL) register bits for the I
2
C clock and data pins should be set (see
examples in “Initialization and Configuration” on page 753).
Note: This register has no effect on port pins
PL6
and
PL7
.
GPIO Open Drain Select (GPIOODR)
GPIO Port A (AHB) base: 0x4005.8000
GPIO Port B (AHB) base: 0x4005.9000
GPIO Port C (AHB) base: 0x4005.A000
GPIO Port D (AHB) base: 0x4005.B000
GPIO Port E (AHB) base: 0x4005.C000
GPIO Port F (AHB) base: 0x4005.D000
GPIO Port G (AHB) base: 0x4005.E000
GPIO Port H (AHB) base: 0x4005.F000
GPIO Port J (AHB) base: 0x4006.0000
GPIO Port K (AHB) base: 0x4006.1000
GPIO Port L (AHB) base: 0x4006.2000
GPIO Port M (AHB) base: 0x4006.3000
GPIO Port N (AHB) base: 0x4006.4000
GPIO Port P (AHB) base: 0x4006.5000
GPIO Port Q (AHB) base: 0x4006.6000
Offset 0x50C
Type RW, reset 0x0000.0000
16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31
reserved
RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO RO Type
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Reset
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
ODE reserved
RW RW RW RW RW RW RW RW RO RO RO RO RO RO RO RO Type
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Reset
Description Reset Type Name Bit/Field
Software should not rely on the value of a reserved bit. To provide
compatibility with future products, the value of a reserved bit should be
preserved across a read-modify-write operation. 0x0000.00 RO reserved 31:8
Output Pad Open Drain Enable
Description Value
The corresponding pin is not configured as open drain. 0
The corresponding pin is configured as open drain. 1
0x00 RW ODE 7:0
775 June 18, 2014
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Tiva
™
TM4C1294NCPDT Microcontroller