CS5376A datasheet(69/107 Pages) CIRRUS

69 / 107 page

CS5376A

19. GENERAL PURPOSE I/O

The General Purpose I/O (GPIO) block provides 12

general purpose pins to interface with external

hardware.

19.1 Pin Descriptions

GPIO[4:0]:CS[4:0] - Pins 32 - 36

Standard GPIO pins also used as SPI 2 chip selects.

GPIO[5:10] - Pins 37, 41 - 45

Standard GPIO pins.

GPIO11:EECS - Pin 46

Standard GPIO pin also used as an SPI 1 chip select

when booting from an external EEPROM.

19.2 GPIO Architecture

Each GPIO pin can be configured as input or out-

put, high or low, with a weak (~200 k

Ω) internal

pull-up resistor enabled or disabled. Several GPIO

pins also double as chip selects for the SPI 1 and

SPI 2 serial ports. Figure 38 shows the structure of

a bi-directional GPIO pin with SPI chip select func-

tionality.

When the CS5376A is used as an SPI master, either

when booting from EEPROM using SPI 1 or per-

forming master mode transactions using SPI 2, the

chip select signals from SPI 1 and SPI 2 are logi-

cally AND-ed with the GPIO data bit. The corre-

sponding GPIO pin should be initialized as output

mode and logical 1 to produce the chip select fall-

ing edge.

19.3 GPIO Registers

When used as standard GPIO pins, settings are pro-

grammed in the GPCFG0 and GPCFG1 registers.

GP_DIR bits set the input/output mode, GP_PULL

bits enable/disable the internal pull-up resistor, and

GP_DATA bits set the output data value. After re-

set, GPIO pins default as inputs with pull-up resis-

tors enabled.

19.4 GPIO Input Mode

When reading a value from the GP_DATA bits, the

returned data reports the current state of the pins. If

a pin is externally driven high it reads a logical 1, if

externally driven low it reads a logical 0. When a

GPIO pin is used as an input, the pull-up resistor

should be disabled to save power if it isn’t required.

19.5 GPIO Output Mode

When a GPIO pin is programmed as an output with

a data value of 0, the pin is driven low and the in-

ternal pull-up resistor is automatically disabled.

When programmed as an output with a data value

of 1, the pin is driven high and the pull-up resistor

is inconsequential.

Figure 38. GPIO Bi-directional Structure

CS output from SPI

GPIO/CS

GP_DIR

Data bit

GP_DATA

GP_PULL

Pull Up

Logic

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