AD5933 datasheet(26/40 Pages) AD

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AD5933

Data Sheet

Rev. E | Page 26 of 40

STATUS REGISTER (REGISTER ADDRESS 0x8F)

The status register is used to confirm that particular measure-

ment tests have been successfully completed. Each of the bits

from D7 to D0 indicates the status of a specific functionality of

the AD5933.

Bit D0 and Bit D4 to Bit D7 are treated as don’t care bits These

bits do not indicate the status of any measurement.

The status of Bit D1 indicates the status of a frequency point

impedance measurement. This bit is set when the AD5933 has

completed the current frequency point impedance measurement.

This bit indicates that there is valid real data and imaginary data

in Register Address 0x94 to Register Address 0x97. This bit is

reset on receipt of a start frequency sweep, increment frequency,

repeat frequency, or reset command. This bit is also reset on

power-up.

The status of Bit D2 indicates the status of the programmed

frequency sweep. This bit is set when all programmed incre-

ments to the number of increments register are complete. This

bit is reset on power-up and on receipt of a reset command.

Table 14. Status Register (Register Address 0x8F)

Control Word

Function

0000 0001

Valid temperature measurement

0000 0010

Valid real/imaginary data

0000 0100

Frequency sweep complete

0000 1000

Reserved

0001 0000

Reserved

0010 0000

Reserved

0100 0000

Reserved

1000 0000

Reserved

Valid Temperature Measurement

The valid temperature measurement control word is set when a

valid temperature conversion is complete indicating that valid

temperature data is available for reading at Register Address

0x92 and Register Address 0x93. It is reset when a temperature

measurement takes place as a result of a measure temperature

command having been issued to the control register (Register

Address 0x80 and Register Address 0x81) by the user.

Valid Real/Imaginary Data

D1 is set when data processing for the current frequency point

is finished, indicating real/imaginary data available for reading.

D1 is reset when a start frequency sweep/increment frequency/

repeat frequency DDS start/increment/repeat command is

issued. D1 is reset to 0 when a reset command is issued to the

control register.

Frequency Sweep Complete

D2 is set when data processing for the last frequency point in the

sweep is complete. This bit is reset when a start frequency sweep

command is issued to the control register. This bit is also reset

when a reset command is issued to the control register.

TEMPERATURE DATA REGISTER

(16 BITS—REGISTER ADDRESS 0x92,

These registers contain a digital representation of the temper-

ature of the AD5933. The values are stored in 16-bit, twos

complement format. Bit D15 and Bit D14 are don’t care bits.

Bit 13 is the sign bit. To convert this number to an actual

temperature, refer to the Temperature Conversion Formula

section.

REAL AND IMAGINARY DATA REGISTERS (16

BITS—REGISTER ADDRESS 0x94, REGISTER

ADDRESS 0x95, REGISTER ADDRESS 0x96,

The default value upon reset is as follows: these registers are not

reset on power-up or on receipt of a reset command. Note that

the data in these registers is valid only if Bit D1 in the status

frequency point is complete.

These registers contain a digital representation of the real

and imaginary components of the impedance measured for

the current frequency point. The values are stored in 16-bit,

twos complement format. To convert this number to an actual

impedance value, the magnitude—√(Real2 + Imaginary2)—must

be multiplied by an admittance/code number (called a gain

factor) to give the admittance, and the result inverted to give

impedance. The gain factor varies for each ac excitation

voltage/gain combination.

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