AD5593R datasheet(30/34 Pages) AD

30 / 34 page

Data Sheet

AD5593R

Rev. B | Page 29 of 33

GPIO OPERATION

Each of the I/Ox pins of the AD5593R can be configured to

operate as a general-purpose, digital input or output pin. The

function of the pins is determined by writing to the appropriate

bit in the GPIO read configuration and GPIO write configuration

registers using the 4-byte I2C write shown in Figure 34.

Setting Pins as Outputs

To set a pin as a general-purpose output, set the appropriate bit

in the GPIO write configuration register to 1. For example,

setting Bit D0 to 1 enables I/O0 as a general-purpose output.

The outputs can be independently configured as push/pull or

open-drain outputs. When in push/pull configuration, the

output is driven to VDD or GND as determined by the data in

the GPIO write data register. When in open-drain configuration,

the output is driven to GND when a data bit in the GPIO write

data register sets the pin low. When the pin is set high, the

output is not driven and must be pulled high by an external

resistor. This allows multiple output pins to be tied together. If

all the pins are normally high, it allows one pin to pull down the

others. This is commonly used where multiple pins are used to

trigger an alarm or interrupt pin. The state of the output pin is

controlled by setting or clearing the bits in the GPIO write data

written to a location that is not configured as an output.

Table 21. GPIO Write Configuration Register Descriptions

Bits

Description

D15 to D8

Reserved; set these bits to 0

D7 to D0

Select pins as GPIO outputs

D[7:0] = 1: I/O[7:0] is a general-purpose output pin

D[7:0] = 0: I/O[7:0] function is determined by the

pin configuration registers (default)

Table 22. GPIO Open-Drain Control Register Descriptions

Bits

Description

D15 to D8

Reserved; set these bits to 0

D7 to D0

Sets output pins as open-drain

D[7:0] = 1: I/O[7:0] is an open-drain output pin

D[7:0] = 0: I/O[7:0] is a push/pull output pin

(default)

Table 23. GPIO Write Data Register Descriptions

Bits

Description

D15 to D8

Reserved; set these bits to 0

D7 to D0

Sets the state of a GPIO output

D[7:0] = 1: I/O[7:0] is a Logic 1

D[7:0] = 0: I/O[7:0] is a Logic 0 (default)

Setting Pins as Inputs

To set an I/Ox pin as a general-purpose input, set the

appropriate bit in the GPIO read configuration register to 1. For

example, setting Bit D0 to 1 enables I/O0 as a general-purpose

input. To read the state of general-purpose inputs, set the

pointer byte to 0b01100000 (see Table 10 ) using any of the read

operations shown in Figure 35, Figure 36, and Figure 37. The

status of any I/O pin set as a general-purpose input appears in

the appropriate bit location in the least significant data byte.

Three-State Pins

The I/Ox pins can be set to three-state by writing to the three-

state configuration register (pointer byte = 0b00001101) as

shown in Table 24.

Table 24. Three-State Configuration Register Descriptions

Bits

Description

D15 to D8

Reserved; set these bits to 0

D7 to D0

Set pins as three-state outputs

D[7:0] = 1: I/O[7:0] is a three-state output pin

D[7:0] = 0: I/O[7:0] function is determined by the

pin configuration registers (default)

85 kΩ Pull-Down Pins

The I/Ox pins can be connected to GND via a pull-down

resistor (85 kΩ) by setting the appropriate bits in the pull-down

configuration register (pointer byte = 00000110) as shown in

Table 25.

Table 25. Pull-Down Configuration Register Descriptions

Bits

Description

D15 to D8

Reserved; set these bits to 0

D7 to D0

Set pins as weak pull-down outputs

D[7:0] = 1: I/O[7:0 is connected to GND via an 85 kΩ

pull-down resistor

D[7:0] = 0: I/O[7:0] function is determined by the

pin configuration registers (default)

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