EVAL-AD5933EBZ Datasheet, PDF (15/32 Pages) Analog Devices – Evaluation Board for the 1 MSPS 12-Bit Impedance Converter Network Analyzer

Preliminary Technical Data
SOURCE CODE FOR IMPEDANCE SWEEPS
PROGRAM FREQUENCY SWEEP PARAMETERS
INTO RELEVANT REGISTERS.
(1) START FREQUENCY REGISTER
(2) NUMBER OF INCREMENTS REGISTER
(3) FREQUENCY INCREMENT REGISTER
EVAL-AD5933EB
RESET: BY ISSUING A RESET COMMAND TO
THE CONTROL REGISTER, THE DEVICE IS
PLACED INTO STANDBY MODE.
PLACE THE AD5933 INTO STANDBY MODE.
PROGRAM INITIALIZE WITH START
FREQUENCY COMMAND TO THE CONTROL
REGISTER.
PROGRAM START FREQUENCY SWEEP
COMMAND IN THE CONTROL REGISTER, AFTER
A SUFFICIENT AMOUNT OF SETTLING TIME
HAS ELAPSED.
POLL STATUS REGISTER TO CHECK IF
THE DFT CONVERSION IS COMPLETE.
NO
YES
READ VALUES FROM REAL AND
IMAGINARY DATA REGISTER.
YES
POLL STATUS REGISTER TO CHECK IF
FREQUENCY SWEEP IS COMPLETE.
YES
PROGRAM THE AD5933
INTO POWER-DOWN MODE.
Figure 26. Sweep Flowchart
PROGRAM THE INCREMENT FREQUENCY OR
THE REPEAT FREQUENCY COMMAND TO THE
CONTROL REGISTER.
NO
This section outlines the evaluation board code structure required
to set up the AD5933 frequency sweep. The sweep flow outline is
shown in Figure 26. Each section of the flowchart will be explained
with the help of Visual Basic code extracts. The evaluation board
source code (Visual Basic) is available upon request from the
Analog Devices Technical Support Center. The firmware code
(C code), which is downloaded to the USB microcontroller
connected to the AD5933, implements the low level I²C signal
control (that is, read and write vendor requests).
The Evaluation Board Source Code Extract section provides an
example of how to program a single frequency sweep, starting at
30 KHz, with a frequency step of 10 Hz and 150 points in the
sweep. The code assumes that a 16 MHz clock signal is connected
to Pin 8 (the MCLK pin) of the AD5933. The impedance range
being tested is from 90 kΩ to 110 kΩ. The gain factor is calculated
at the midpoint of the frequency sweep, that is, 30.750 kHz. The
calibration is carried out with a 100 kΩ resistor connected between
VOUT and VIN. The feedback resistor is 100 kΩ.
The first step in Figure 26 is to program the three sweep
parameters that are necessary to define the frequency sweep
(that is, the start frequency, the frequency increment, and the
number of frequency increments in the sweep). Refer to the
AD5933 data sheet for more details.
Rev. PrC | Page 15 of 32