ADA4254ACPZ-R7 datasheet(50/59 Pages) AD

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ADA4254

Data Sheet

Rev. B | Page 50 of 59

GPIO DIRECTION REGISTER (GPIO_DIR) DETAILS

Table 22. GPIO_DIR Register Details (Register 0x08)

Bit

Name

Bit 7

Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0

Reserved

GPIO_DIR[6:0]

Access

Reserved

Reset

Reserved

Bits[6:0], GPIO_DIR—GPIO Direction Configuration

The GPIO_DIR bit field is used to configure each GPIO as either

an input or an output. Setting a bit in this bit field to 1 configures

the corresponding GPIO as an output. Clearing a bit in this bit

field to 0 configures the corresponding GPIO as an input.

SEQUENTIAL CHIP SELECT REGISTER (SCS)

DETAILS

Table 23. SCS Register Details (Register 0x09)

Bit

Name

Bit 7

Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0

Reserved

SCS[6:0]

Access

Reserved

Reset

Reserved

Bits[6:0], SCS—Sequential Chip Select Configuration

Bits[6:0] configure the GPIO pins as sequential chip select

(SCS) pins. Setting any bit in SCS[6:0] to 1 and configuring the

respective GPIO as an output via the GPIO_DIR register makes

that GPIO function as a chip select pin for a slave device. When

SCS is used, the first CS pulse addresses the first GPIO

configured for SCS. Subsequent CS pulses address the

remainder of the GPIOs configured for SCS, and the last CS

pulse addresses the ADA4254. This sequence repeats in a round

robin format until the ADA4254 is configured otherwise. This

process is shown in Figure 108.

Slave SCS lines may require pull-up resistors to avoid

inadvertently communicating with slave devices during SCS

configuration.

LEAVE

SCS ON

TURN

SCS OFF

ALL

COMMANDS

GO TO

ADA4254

IF SCS0 IS

SET PROGRAM

SLAVE WITH

GPIO0 ELSE

PASS

IF SCS3 IS

SET PROGRAM

SLAVE WITH

GPIO3 ELSE

PASS

IF SCS4 IS

SET PROGRAM

SLAVE WITH

GPIO4 ELSE

PASS

IF SCS1 IS

SET PROGRAM

SLAVE WITH

GPIO1 ELSE

PASS

IF SCS2 IS

SET PROGRAM

SLAVE WITH

GPIO2 ELSE

PASS

IF SCS6 IS

SET PROGRAM

SLAVE WITH

GPIO6 ELSE

PASS

IF SCS5 IS

SET PROGRAM

SLAVE WITH

GPIO5 ELSE

PASS

CONFIGURE

SCS

PROGRAM

ADA4254

Figure 108. Sequential Chip Select Flowchart

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ADA4254ACPZ-R7 数据表(PDF) 50 Page - Analog Devices

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