EVAL-AD5933EB

Preliminary Technical Data

Rev. PrC | Page 16 of 32

EVALUATION BOARD SOURCE CODE EXTRACT

‘-------------------------------------------------------------------------------------------------------

‘Code developed using visual basic® 6.

‘Datatype

range

‘Byte

0-255

‘Double

-1.797e308 to – 4.94e-324 and 4.94e-324 to 1.7976e308

‘Integer

-32,768 to 32767

‘Long

-2,147,483,648 to 2,147,483,647

‘Variant‘...when storing numbers same range as double. When storing strings same range as string.

‘-------------------------------------- Variable Declarations -----------------------------------------

Dim ReadbackStatusRegister As Long

'stores the contents of the status register.

Dim RealData As Double

'used to store the 16 bit 2s complement real data.

Dim RealDataUpper As Long

'used to store the upper byte of the real data.

Dim RealDataLower As Long

'used to store the lower byte of the real data.

Dim ImagineryData As Double

'used to store the 16 bit 2s complement real data.

Dim ImagineryDataLower As Long

'used to store the upper byte of the imaginary data.

Dim ImagineryDataUpper As Long

'used to store the lower byte of the imaginary data.

Dim Magnitude As Double

'used to store the sqrt (real^2+imaginary^2).

Dim Impedance As Double

'used to store the calculated impedance.

Dim MaxMagnitude As Double

'used to store the max impedance for the y axis plot.

Dim MinMagnitude As Double

'used to store the min impedance for the y axis plot.

Dim sweep_phase As Double

'used to temporarily store the phase of each sweep point.

Dim Frequency As Double

'used to temporarily store the current sweep frequency.

Dim Increment As Long

'used as a temporary counter

Dim i As Integer

'used as a temporary counter in (max/min) mag,phase loop

Dim xy As Variant

'used in the stripx profile

Dim varray As Variant

Dim Gainfactor as double

‘either a single mid point calibration or an array of calibration points

Dim TempStartFrequency

As Double

Dim StartFrequencybyte0

As Long

Dim StartFrequencybyte2

As Long

Dim StartFrequencybyte1A

As Long

Dim StartFrequencybyte1B

As Long

Dim DDSRefClockFrequency

As Double

Dim NumberIncrementsbyte0

As Long

Dim NumberIncrementsbyte1

As Long

Dim FrequencyIncrementbyt0 As Long

Dim FrequencyIncrementbyt1 As Long

Dim FrequencyIncrementbyt2 As Long

Dim SettlingTimebyte0

As Long

Dim SettlingTimebyte1

As Long

‘-------------------------------------- I^2C read/write definitions-----------------------------------------

‘used

in

the

main

sweep

routine

to

read

and

write

to

AD5933.This

is

the

vendor

request

routines

in

the

firmware

Private Sub WritetToPart(RegisterAddress As Long, RegisterData As Long)

PortWrite &HD, RegisterAddress, RegisterData

‘parameters = device address register address register data

End Sub

Public Function PortWrite(DeviceAddress As Long, AddrPtr As Long, DataOut As Long) As Integer

PortWrite = VendorRequest(VRSMBus, DeviceAddress, CLng(256 * DataOut + AddrPtr), VRWRITE, 0, 0)

End Function

Public Function PortRead(DeviceAddress As Long, AddrPtr As Long) As Integer

PortRead = VendorRequest(VRSMBus, DeviceAddress, AddrPtr, VRREAD, 1, DataBuffer(0))

PortRead = DataBuffer(0)

End Function

‘------------------------------------- PHASE CONVERSION FUNCTION DEFINITION --------------------------------

‘This function accepts the real and imaginary data(R, I) at each measurement sweep point and converts it to

a degree

‘-----------------------------------------------------------------------------------------------------------

Public Function phase_sweep (ByVal img As Double, ByVal real As Double) As Double

Dim theta As Double

Dim pi As Double

pi = 3.141592654

If ((real > 0) And (img > 0)) Then

theta = Atn(img / real)

' theta = arctan (imaginary part/real part)