AD7280ABSTZ datasheet(39/48 Pages) AD

39 / 48 page

AD7280A

Rev. 0 | Page 39 of 48

Example 1: Initialize All Parts in a Daisy Chain on Initial

Power-Up and When Coming Out of Power-Down

Example 1 shows a typical device initialization routine.

To initialize all device addresses, set Bit D2 and Bit D0

of the control register to 1, and set Bit D1 of the control

command is 0x01C2B6E2 (see Table 23, Write 1).

Write the register address corresponding to the lower byte

of the control register to the read register on all parts. The

32-bit write command is 0x038716CA (see Table 23, Write 2).

Apply a CS low pulse that frames 32 SCLKs for each device

in the chain to be read back. All conversion readbacks

should simultaneously write the 32-bit command

0xF800030A, as described in the

section

(see

, Write 3). This read is used to verify that all

AD7280As in the chain have received and locked their

unique device addresses. Confirm that all device addresses

are in sequence.

Serial Interface

Table 23

Example 2: Convert and Read All Parts, All Voltages,

and All Auxiliary ADC Inputs

In this example, it is assumed that all AD7280As in the daisy

chain have been initialized to their correct device addresses.

Write Register Address 0x00 to the read register on all

parts. A device address of 0x00 is used when computing

the CRC for commands to write to all parts. The 32-bit

write command is 0x38011CA (see Table 24, Write 1).

Note that 0x00 is the default value of the read register on

power-up and after a software reset; therefore, this write

operation may not be necessary.

Set Bits[D15:D12] of the control register to 0 on all parts.

The 32-bit write command is 0x01A0131A (see Table 24,

Write 2).

Note that this is the default value of Bits[D15:D12] of the

control register on power-up and after a software reset;

therefore, this write operation may not be necessary.

Program the CNVST control register to 0x02 on all parts

to allow conversions to be initiated using the CNVST pin.

The 32-bit write command is 0x03A0546A (see

Write 3).

Table 24

Initiate conversions through the falling edge of CNVST.

Allow sufficient time for all conversions to be completed

plus tWAIT. Following the completion of all conversions,

apply a CS low pulse that frames 32 SCLKs for each conver-

sion result to be read back. The 32-bit write command is

0xF800030A, as described in the

section

(see

, Write 4).

Serial Interface

Table 24

Table 23. Example 1: Initializing All AD7280A Devices in a Daisy Chain

Write Command

Device Address

Data

Write All

D11

8-Bit CRC

D2 to D0

32-Bit Write

Command

Write 1

00000

001110

00010101

11011100

010

0x01C2B6E2

Write 2

00000

011100

00111000

11011001

010

0x038716CA

Write 3

11111

000000

00000000

01100001

010

0xF800030A

Table 24. Example 2: Converting and Reading All Voltages and All Auxiliary ADC Inputs from All AD7280A Devices

Write Command

Device Address

Data

Write All

D11

8-Bit CRC

D2 to D0

32-Bit Write

Command

Write 1

00000

011100

00000000

00111001

010

0x038011CA

Write 2

00000

001101

00000000

01100011

010

0x01A0131A

Write 3

00000

011101

00000010

10000101

010

0x03A0546A

Write 4

11111

000000

00000000

01100001

010

0xF800030A

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