AD7147 datasheet(38/68 Pages) AD

38 / 68 page

AD7147

Rev. 0 | Page 38 of 68

POWER-UP SEQUENCE

To power up the AD7147, use the following sequence when

initially developing the AD7147 and μP serial interface:

Turn on the power supplies to the AD7147.

Write to the Bank 2 registers at Address 0x080 through

Address 0x0DF. These registers are contiguous; therefore, a

sequential register write sequence can be applied.

Note that the Bank 2 register values are unique for each

application. Register values come from characterization of

the sensor in the application. The characterization process

is outlined in the AN-929 Application Note, available from

Analog Devices.

Write to the Bank 1 registers at Address 0x000 through

Address 0x007 as outlined below. These registers are

contiguous; therefore, a sequential register write sequence

can be applied (see Figure 49 and Figure 54).

Caution: At this time, Address 0x001 must remain set to

default value 0x0000 during this contiguous write operation.

Address 0x000 = 0x82B2

Address 0x001 = 0x000

Address 0x002 = 0x3230 (depends on number of

conversion stages used)

Address 0x003 = 0x419

Address 0x004 = 832

Address 0x005 = interrupt enable register (depends on

required interrupt behavior)

Address 0x006 = interrupt enable register (depends on

required interrupt behavior)

Address 0x007 = interrupt enable register (depends on

required interrupt behavior)

Write to the Bank 1 register, Address 0x001 = 0x0FFF

(depends on number of conversion stages used).

Read back the corresponding interrupt status register at

Address 0x008, Address 0x009, or Address 0x00A. This is

determined by the interrupt output configuration, as

explained in the Interrupt Output section.

Note that the specific registers required to be read back

depend on each application. For buttons, the interrupt

status registers are read back while other sensors read data

back from the AD7147 according to the slider or wheel

algorithm’s requirements. Analog Devices can provide this

information after the user develops the sensor board.

Repeat Step 5 every time INT is asserted.

FIRST CONVERSION SEQUENCE

CONVERSION

STAGE

CONVERSION STAGES DISABLED

678

10 11

012

910 11

SECOND CONVERSION

SEQUENCE

THIRD CONVERSION

SEQUENCE

POWER

HOST

SERIAL

INTERFACE

AD7147 INT

Figure 58. Recommended Start-Up Sequence

AD7147 Datasheet(PDF) 38 Page - Analog Devices

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