Datasheet
TCA7408
SCPS235B –NOVEMBER 2011–REVISED MARCH 2013
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Register 07h – Output High-Impedance
The Output High-Impedance Register determines whether pins set as output are enabled or high-impedance
• When a bit in this register is set to 0, the corresponding GPIO-port output state follows register the output port
register (05h).
• When a bit in this register is set to 1, the corresponding GPIO-port output is set to high-impedance.
• Bit values in this register have no effect on pins defined as inputs. In turn, reads from this register reflect the
value that is in the flip-flop controlling the output selection, not the actual pin value.
BIT B7 B6 B5 B4 B3 B2 B1 B0
DESCRIPTION GPIO7 GPIO6 GPIO5 GPIO4 GPIO3 GPIO2 GPIO1 GPIO0
DEFAULT 1 1 1 1 1 1 1 1
Register 09h – Input Default State
The Input Default State Register sets the default state of the GPIO-port input for generating interrupts.
• When a bit in this register is set to 0, the default for the corresponding input is set to LOW
• When a bit in this register is set to 1, the default for the corresponding input is set to HIGH
• Bit values in this register have no effect on pins defined as outputs. In turn, reads from this register reflect the
value that is in the flip-flop controlling the default state, not the actual pin value.
BIT B7 B6 B5 B4 B3 B2 B1 B0
DESCRIPTION GPIO7 GPIO6 GPIO5 GPIO4 GPIO3 GPIO2 GPIO1 GPIO0
DEFAULT 1 1 1 1 1 1 1 1
Register 0Bh – Pull-up/-down Enable
The Pull-up/-down Enable Register enables or disables the pull-up/down resistor on the GPIO-port as defined in
the Pull-up/down Select Register (0Dh).
• When a bit in this register is set to 0, the pull-up/down on the corresponding GPIO is disabled.
• When a bit in this register is set to 1, the pull-up/down on the corresponding GPIO is enabled.
BIT B7 B6 B5 B4 B3 B2 B1 B0
DESCRIPTION GPIO7 GPIO6 GPIO5 GPIO4 GPIO3 GPIO2 GPIO1 GPIO0
DEFAULT 1 1 1 1 1 1 1 1
Register 0Dh – Pull-up/-down Select
The Pull-up/down Select Register allows the user to select either a pull-up or pull-down on the GPIO-port. This
register only selects the pull-up/down resistor on the GPIO-port, while the enabling/disabling is controlled by the
Pull-up/down Enable Register (0Bh).
• When a bit in this register is set to 0, the pull-down on the corresponding GPIO is selected.
• When a bit in this register is set to 1, the pull-up on the corresponding GPIO is selected.
BIT B7 B6 B5 B4 B3 B2 B1 B0
DESCRIPTION GPIO7 GPIO6 GPIO5 GPIO4 GPIO3 GPIO2 GPIO1 GPIO0
DEFAULT 0 0 0 0 0 0 0 0
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