EVAL-AD5933EBZ Datasheet, PDF (17/32 Pages) Analog Devices – Evaluation Board for the 1 MSPS 12-Bit Impedance Converter Network Analyzer

Preliminary Technical Data
EVAL-AD5933EB
phase2 = (theta * 180) / pi
'convert from radians to degrees
ElseIf ((real > 0) And (img < 0)) Then
theta = Atn(img / real)
phase2 = ((theta * 180) / pi ) +360
'4th quadrant theta = minus angle
ElseIf ((real < 0) And (img < 0)) Then
theta = -pi + Atn(img / real)
phase2 = (theta * 180) / pi
'3rd quadrant theta img/real is positive
ElseIf ((real < 0) And (img > 0)) Then
theta = pi + Atn(img / real)
phase2 = (theta * 180) / pi
'2nd quadrant img/real is neg
End If
End Function
‘-----------------------------------------------------------------------------------------------------------
Private Sub Sweep ()
’ the main sweep routine
‘This routine coordinates a frequency sweep using a mid point gain factor (see datasheet).
'The gain factor at the mid-point is determined from the real and imaginary contents returned at this mid
‘point frequency and the calibration impedance.
'The bits of the status register are polled to determine when valid data is available and when the sweep is
‘complete.
'-----------------------------------------------------------------------------------------------------------
IndexArray = 0
'initialize counter variable.
Increment = NumberIncrements + 1 'number of increments in the sweep.
Frequency = StartFrequency
'the sweep starts from here.
‘------------------------- PROGRAM 30K Hz to the START FREQUENCY register ---------------------------------
DDSRefClockFrequency = 16E6
StartFrequency = 30E3
‘Assuming a 16M Hz clock connected to MCLK
‘frequency sweep starts at 30K Hz
TempStartFrequency = (StartFrequency / (DDSRefClockFrequency / 4)) * 2^27 ‘dial up code for the DDS
TempStartFrequency = Int(TempStartFrequency) ‘30K Hz = 0F5C28 hex
StartFrequencybyte0 = 40
StartFrequencybyte1 = 92
StartFrequencybyte2 = 15
‘40 DECIMAL = 28 HEX
‘92 DECIMAL = 5C HEX
’15 DECIMAL = 0F HEX
'Write in data to Start frequency register
WritetToPart &H84, StartFrequencybyte0 '84 hex lsb
WritetToPart &H83, StartFrequencybyte1 '83 hex
WritetToPart &H82, StartFrequencybyte2 '82 hex
‘--------------------------------- PROGRAM the NUMBER OF INCREMENTS register ------------------------------
‘The sweep is going to have 150 points 150 DECIMAL = 96 hex
'Write in data to Number Increments register
WritetToPart &H89, 96
‘lsb
WritetToPart &H88, 00
‘msb
‘--------------------------------- PROGRAM the FREQUENCY INCREMENT register ------------------------------
‘The sweep is going to have a frequency increment of 10Hz between successive points in the sweep
DDSRefClockFrequency = 16E6
FrequencyIncrements = 10
‘Assuming a 16M Hz clock connected to MCLK
‘frequency increment of 10Hz
TempStartFrequency = (FrequencyIncrements / (DDSRefClockFrequency / 4)) * 2^27 ‘dial up code for the DDS
TempStartFrequency = Int(TempStartFrequency) ’10 Hz = 335 decimal = 00014F hex
FrequencyIncrementbyt0 = 4F
FrequencyIncrementbyt1 = 01
FrequencyIncrementbyt2 = 00
‘335 decimal = 14f hex
'Write in data to frequency increment register
WritetToPart &H87, FrequencyIncrementbyt0 '87 hex lsb
WritetToPart &H86, FrequencyIncrementbyt1 '86 hex
WritetToPart &H85, FrequencyIncrementbyt2 '85 hex msb
‘--------------------------------- PROGRAM the SETTLING TIME CYCLES register ------------------------------
Rev. PrC | Page 17 of 32