Datasheet

ADAU1761

Rev. C | Page 50 of 92

GENERAL-PURPOSE INPUT/OUTPUT

The serial data input/output pins (Pin 26 to Pin 29) are shared

with the general-purpose input/output function. Each of these

four pins can be set to only one of these functions. The function

of these pins is set in the serial data/GPIO pin configuration

The GPIOx pins can be used as inputs or outputs. These pins

are readable and can be set through the control port or directly

by the SigmaDSP core. When configured as inputs, the GPIOx

pins can be used with push-button switches or rotary encoders

to control DSP program settings. These pins can also be used

with digital outputs to drive LEDs or external logic to indicate

the status of internal signals and control other devices. Examples

of this use include indicating signal overload, signal present,

and button press confirmation.

When configured as an output, each GPIO pin can typically

drive 2 mA, which is enough current to directly drive some

high efficiency LEDs. Standard LEDs require about 20 mA of

current and can be driven from a GPIO output with an external

transistor or buffer. Because of problems that can arise from

simultaneously driving or sinking a large amount of current on

many pins, avoid connecting high efficiency LEDs directly to

many or all of the GPIO pins when designing the application.

If many LEDs are required, use an external driver. When the

GPIO pins are configured as open-collector outputs, they

should be pulled up to a maximum voltage equal to the voltage

set on IOVDD.

The configuration of the GPIO functions is set up in the

GPIO pin control registers (Register R48 to Register R51,

Address 0x40C6 to Address 0x40C9).

GPIO PINS SET FROM THE CONTROL PORT

The GPIO pins can also be configured to be directly controlled

from the I

C/SPI control port. When the pins are set to this

mode, four memory locations are enabled for the GPIO pin

settings. The physical settings on the GPIO pins mirror the

settings of the LSB of these 4-byte-wide memory locations.

Table 32. GPIOx Pin Memory Settings (Set from Control Port)

Memory Location

Decimal Hex Bits[31:1] Bit 0

1568 0x0620 Reserved GPIO0SET

1569 0x0621 Reserved GPIO1SET

1570 0x0622 Reserved GPIO2SET

1571 0x0623 Reserved GPIO3SET