Datasheet

TCA7408

www.ti.com

SCPS235B –NOVEMBER 2011–REVISED MARCH 2013

CONTROL REGISTER BITS

COMMAND POWER-UP

BYTE (HEX) DEFAULT

B7 B6 B5 B4 B3 B2 B1 B0

AI 0 0 0 0 0 0 1 01h Device ID and Control Read (B7-B1) Write (B0) 0100 0010

AI 0 0 0 0 0 1 1 03h I/O Direction Read/write byte 0000 0000

AI 0 0 0 0 1 0 1 05h Output State Read/write byte 0000 0000

AI 0 0 0 0 1 1 1 07h Output High-Impedance Read/write byte 1111 1111

AI 0 0 0 1 0 0 1 09h Input Default State Read/write byte 0000 0000

AI 0 0 0 1 0 1 1 0Bh Pull-up/down Enable Read/write byte 1111 1111

AI 0 0 0 1 1 0 1 0Dh Pull-up/down Select Read/write byte 0000 0000

AI 0 0 0 1 1 1 1 0Fh Input Status Read byte xxxx xxxx

AI 0 0 1 0 0 0 1 11h Interrupt Mask Read/write byte 0000 0000

AI 0 0 1 0 0 1 1 13h Interrupt Status Read byte 0000 0000

The Device ID and Control register contains the manufacturer ID and firmware revision. The Control register

indicates whether the device has been reset and the default values have been set.

• The Reset Interrupt is set B1=1 when the device is either reset by the RESET pin, a power on reset, or

software reset.

• Reset Interrupt is then cleared after being read by the master.

• Writing to B7–B1 has no effect on these bits in the register.

• A software reset is issued when the master writes B0=1.

• When reading from B0, the value read will always be 0.

BIT B7 B6 B5 B4 B3 B2 B1 B0

DESCRIPTION Manufacturer ID Firmware Revision Reset Interrupt Software Reset

DEFAULT 0 1 0 0 0 0 1 0

The I/O Direction Register configures the direction of the I/O pins.

• If a bit in this register is set to 0, the corresponding port pin is enabled as an input

• If a bit in this register is set to 1, the corresponding port pin is enabled as an output.

• When the port is set as an output the input buffers are disabled such that the bus can float.

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

The Output Port Register sets the outgoing logic levels of the pins defined as outputs.

• When Bx is set to 0, GPIOx = L

• When Bx is set to 1, GPIOx = H

• Bit values in this register have no effect on pins defined as inputs

• 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 0 0 0 0 0 0 0 0

Product Folder Links :TCA7408