gettin gooder

Impedance.c

@@ -1,4 +1,4 @@
-// Impedance.c
+// File: Impedance.c
 #include "ad5940.h"
 #include <stdio.h>
 #include "string.h"
@@ -295,7 +295,8 @@ static AD5940Err AppIMPSeqMeasureGen(void)
                 AFECTRL_WG|AFECTRL_DACREFPWR|AFECTRL_HSDACPWR|\
                 AFECTRL_SINC2NOTCH, bTRUE);
   AD5940_AFECtrlS(AFECTRL_WG|AFECTRL_ADCPWR, bTRUE); 
-  AD5940_SEQGenInsert(SEQ_WAIT(16*10)); // Settling
+  // Increased settling time to 2000us (16*2000) to ensure stability
+  AD5940_SEQGenInsert(SEQ_WAIT(16*2000)); 
   AD5940_AFECtrlS(AFECTRL_ADCCNV|AFECTRL_DFT, bTRUE); 
   
   AD5940_SEQGenFetchSeq(NULL, &AppIMPCfg.SeqWaitAddr[0]); 
@@ -317,7 +318,8 @@ static AD5940Err AppIMPSeqMeasureGen(void)
   AD5940_ADCMuxCfgS(ADCMUXP_HSTIA_P, ADCMUXN_HSTIA_N);
 
   AD5940_AFECtrlS(AFECTRL_ADCPWR|AFECTRL_WG, bTRUE); 
-  AD5940_SEQGenInsert(SEQ_WAIT(16*10)); 
+  // Increased settling time to 2000us
+  AD5940_SEQGenInsert(SEQ_WAIT(16*2000)); 
   AD5940_AFECtrlS(AFECTRL_ADCCNV|AFECTRL_DFT, bTRUE); 
   
   AD5940_SEQGenFetchSeq(NULL, &AppIMPCfg.SeqWaitAddr[1]); 
@@ -335,7 +337,8 @@ static AD5940Err AppIMPSeqMeasureGen(void)
   AD5940_ADCMuxCfgS(ADCMUXP_AIN2, ADCMUXN_AIN3);
 
   AD5940_AFECtrlS(AFECTRL_ADCPWR|AFECTRL_WG, bTRUE); 
-  AD5940_SEQGenInsert(SEQ_WAIT(16*10)); 
+  // Increased settling time to 2000us
+  AD5940_SEQGenInsert(SEQ_WAIT(16*2000)); 
   AD5940_AFECtrlS(AFECTRL_ADCCNV|AFECTRL_DFT, bTRUE); 
   
   AD5940_SEQGenFetchSeq(NULL, &AppIMPCfg.SeqWaitAddr[2]); 
@@ -370,7 +373,6 @@ AD5940Err AppIMPCheckFreq(float freq)
 {
   ADCFilterCfg_Type filter_cfg;
   DFTCfg_Type dft_cfg;
-  // HSDACCfg_Type hsdac_cfg; // Removed to prevent override
   uint32_t WaitClks;
   ClksCalInfo_Type clks_cal;
   FreqParams_Type freq_params;
@@ -379,65 +381,25 @@ AD5940Err AppIMPCheckFreq(float freq)
   
   freq_params = AD5940_GetFreqParameters(freq);
   
-  // CRITICAL FIX: Removed HSDAC and HSRTIA overrides.
+  // Only switch modes if necessary to avoid glitching the sequencer
-  // The configuration set in AppIMPSeqCfgGen (based on user config) should persist.
+  if(freq < 80000)
-  // Overriding HSTIARTIA_5K here while RtiaVal remains 200 causes massive math errors.
-
-  if(freq < 0.51)
   {
-    // hsdac_cfg.ExcitBufGain = EXCITBUFGAIN_2;
+    if (AppIMPCfg.SysClkFreq != 16000000.0) {
-    // hsdac_cfg.HsDacGain = HSDACGAIN_1;
-    // hsdac_cfg.HsDacUpdateRate = 0x1B;
-    // AD5940_HSDacCfgS(&hsdac_cfg);
-    // AD5940_HSRTIACfgS(HSTIARTIA_40K); 
         filter_cfg.ADCRate = ADCRATE_800KHZ;
         AppIMPCfg.AdcClkFreq = 16e6;
+        AppIMPCfg.SysClkFreq = 16000000.0;
         AD5940_HPModeEn(bFALSE);
     }
-  else if(freq < 5 )
-  {
-    // hsdac_cfg.ExcitBufGain = EXCITBUFGAIN_2;
-    // hsdac_cfg.HsDacGain = HSDACGAIN_1;
-    // hsdac_cfg.HsDacUpdateRate = 0x1B;
-    // AD5940_HSDacCfgS(&hsdac_cfg);
-    // AD5940_HSRTIACfgS(HSTIARTIA_40K); 
-    filter_cfg.ADCRate = ADCRATE_800KHZ;
-    AppIMPCfg.AdcClkFreq = 16e6;
-    AD5940_HPModeEn(bFALSE);
   }
-  else if(freq < 450)
+  else
   {
-    // hsdac_cfg.ExcitBufGain = AppIMPCfg.ExcitBufGain;
+    if (AppIMPCfg.SysClkFreq != 32000000.0) {
-    // hsdac_cfg.HsDacGain = AppIMPCfg.HsDacGain;  
-    // hsdac_cfg.HsDacUpdateRate = 0x1B;
-    // AD5940_HSDacCfgS(&hsdac_cfg);
-    // AD5940_HSRTIACfgS(HSTIARTIA_5K); 
-    filter_cfg.ADCRate = ADCRATE_800KHZ;
-    AppIMPCfg.AdcClkFreq = 16e6;
-    AD5940_HPModeEn(bFALSE);
-  }
-  else if(freq<80000)
-  {
-    // hsdac_cfg.ExcitBufGain = AppIMPCfg.ExcitBufGain;
-    // hsdac_cfg.HsDacGain = AppIMPCfg.HsDacGain;
-    // hsdac_cfg.HsDacUpdateRate = 0x1B;
-    // AD5940_HSDacCfgS(&hsdac_cfg);
-    // AD5940_HSRTIACfgS(HSTIARTIA_5K); 
-    filter_cfg.ADCRate = ADCRATE_800KHZ;
-    AppIMPCfg.AdcClkFreq = 16e6;
-    AD5940_HPModeEn(bFALSE);
-  }
-  if(freq >= 80000)
-  {
-    // hsdac_cfg.ExcitBufGain = AppIMPCfg.ExcitBufGain;
-    // hsdac_cfg.HsDacGain = AppIMPCfg.HsDacGain;
-    // hsdac_cfg.HsDacUpdateRate = 0x07;
-    // AD5940_HSDacCfgS(&hsdac_cfg);
-    // AD5940_HSRTIACfgS(HSTIARTIA_5K); 
         filter_cfg.ADCRate = ADCRATE_1P6MHZ;
         AppIMPCfg.AdcClkFreq = 32e6;
+        AppIMPCfg.SysClkFreq = 32000000.0;
         AD5940_HPModeEn(bTRUE);
     }
+  }
   
   filter_cfg.ADCAvgNum = ADCAVGNUM_16; 
   filter_cfg.ADCSinc2Osr = freq_params.ADCSinc2Osr;
@@ -463,8 +425,15 @@ AD5940Err AppIMPCheckFreq(float freq)
   // Update Wait Times for all 3 measurements
   for (int i = 0; i < 3; i++) {
       SRAMAddr = AppIMPCfg.MeasureSeqInfo.SeqRamAddr + AppIMPCfg.SeqWaitAddr[i];
-      SeqCmdBuff[0] = SEQ_WAIT(WaitClks/2);
+      
-      SeqCmdBuff[1] = SEQ_WAIT(WaitClks/2);
+      // CRITICAL FIX: Double the wait time for High Power Mode (>=80kHz)
+      uint32_t finalWait = WaitClks/2;
+      if (freq >= 80000) {
+          finalWait *= 2; 
+      }
+      
+      SeqCmdBuff[0] = SEQ_WAIT(finalWait);
+      SeqCmdBuff[1] = SEQ_WAIT(finalWait);
       AD5940_SEQCmdWrite(SRAMAddr, SeqCmdBuff, 2);
   }
 		
@@ -551,6 +520,7 @@ int32_t AppIMPRegModify(int32_t * const pData, uint32_t *pDataCount)
     if(AppIMPCfg.FifoDataCount >= AppIMPCfg.NumOfData)
     {
       AD5940_WUPTCtrl(bFALSE);
+      AD5940_SEQCtrlS(bFALSE); // Added safety
       return AD5940ERR_OK;
     }
   }
@@ -662,7 +632,12 @@ int32_t AppIMPISR(void *pBuff, uint32_t *pCount)
     }
     AD5940_FIFORd((uint32_t *)pBuff, FifoCnt);
     AD5940_INTCClrFlag(AFEINTSRC_DATAFIFOTHRESH);
-    AppIMPRegModify(pBuff, &FifoCnt);   
+    
+    // Check if sweep is done
+    if (AppIMPRegModify(pBuff, &FifoCnt) != AD5940ERR_OK) {
+        // If sweep is done, we might want to signal main loop
+    }
+    
     AD5940_SleepKeyCtrlS(SLPKEY_UNLOCK); 
     AppIMPDataProcess((int32_t*)pBuff, &FifoCnt); 
     *pCount = FifoCnt;

host/src/GraphWidget.cpp

@@ -1,3 +1,4 @@
+// File: host/src/GraphWidget.cpp
 #include "GraphWidget.h"
 #include <limits>
 #include <cmath>
@@ -13,27 +14,40 @@ GraphWidget::GraphWidget(QWidget *parent) : QWidget(parent) {
     // Setup Graphs
     graph1 = plot->addGraph();
     graph2 = plot->addGraph(plot->xAxis, plot->yAxis2);
+    graph3 = plot->addGraph(plot->xAxis, plot->yAxis2); // Hilbert Trace
 
-    // Style Graph 1 (Primary - Left Axis)
+    // Style Graph 1 (Real - Blue)
     QPen pen1(Qt::blue);
     pen1.setWidth(2);
     graph1->setPen(pen1);
     graph1->setLineStyle(QCPGraph::lsLine);
     graph1->setScatterStyle(QCPScatterStyle(QCPScatterStyle::ssCircle, 3));
-    graph1->setName("Primary");
+    graph1->setName("Real");
 
-    // Style Graph 2 (Secondary - Right Axis)
+    // Style Graph 2 (Imaginary - Red)
     QPen pen2(Qt::red);
     pen2.setWidth(2);
     graph2->setPen(pen2);
     graph2->setLineStyle(QCPGraph::lsLine);
     graph2->setScatterStyle(QCPScatterStyle(QCPScatterStyle::ssTriangle, 3));
-    graph2->setName("Secondary");
+    graph2->setName("Imaginary");
+
+    // Style Graph 3 (Hilbert - Green Dashed)
+    QPen pen3(Qt::green);
+    pen3.setWidth(2);
+    pen3.setStyle(Qt::DashLine);
+    graph3->setPen(pen3);
+    graph3->setLineStyle(QCPGraph::lsLine);
+    graph3->setName("Hilbert (Analytic)");
 
     // Enable Right Axis
     plot->yAxis2->setVisible(true);
     plot->yAxis2->setTickLabels(true);
     
+    // Link Axes for Zooming
+    connect(plot->yAxis, SIGNAL(rangeChanged(QCPRange)), plot->yAxis2, SLOT(setRange(QCPRange)));
+    connect(plot->yAxis2, SIGNAL(rangeChanged(QCPRange)), plot->yAxis, SLOT(setRange(QCPRange)));
+
     // Interactions
     plot->setInteractions(QCP::iRangeDrag | QCP::iRangeZoom);
     
@@ -45,37 +59,7 @@ GraphWidget::GraphWidget(QWidget *parent) : QWidget(parent) {
     plot->legend->setBrush(QBrush(QColor(255, 255, 255, 230)));
     
     // Default Mode
-    configureBodePlot();
+    configureRawPlot();
-}
-
-void GraphWidget::configureBodePlot() {
-    clear();
-    
-    // X Axis: Frequency (Log)
-    plot->xAxis->setLabel("Frequency (Hz)");
-    plot->xAxis->setScaleType(QCPAxis::stLogarithmic);
-    QSharedPointer<QCPAxisTickerLog> logTicker(new QCPAxisTickerLog);
-    plot->xAxis->setTicker(logTicker);
-    plot->xAxis->setNumberFormat("eb"); 
-    
-    // Y Axis 1: Impedance (Log)
-    plot->yAxis->setLabel("Impedance (Ohms)");
-    plot->yAxis->setScaleType(QCPAxis::stLogarithmic);
-    plot->yAxis->setTicker(logTicker); 
-    plot->yAxis->setNumberFormat("eb");
-
-    // Y Axis 2: Phase (Linear)
-    plot->yAxis2->setLabel("Phase (Degrees)");
-    plot->yAxis2->setScaleType(QCPAxis::stLinear);
-    QSharedPointer<QCPAxisTicker> linTicker(new QCPAxisTicker);
-    plot->yAxis2->setTicker(linTicker);
-    plot->yAxis2->setNumberFormat("f");
-    plot->yAxis2->setRange(-180, 180); 
-
-    graph1->setName("Impedance");
-    graph2->setName("Phase");
-    
-    plot->replot();
 }
 
 void GraphWidget::configureRawPlot() {
@@ -86,6 +70,7 @@ void GraphWidget::configureRawPlot() {
     plot->xAxis->setScaleType(QCPAxis::stLogarithmic);
     QSharedPointer<QCPAxisTickerLog> logTicker(new QCPAxisTickerLog);
     plot->xAxis->setTicker(logTicker);
+    plot->xAxis->setNumberFormat("eb");
     
     // Y Axis 1: Real (Linear)
     plot->yAxis->setLabel("Real (Ohms)");
@@ -99,50 +84,82 @@ void GraphWidget::configureRawPlot() {
     plot->yAxis2->setScaleType(QCPAxis::stLinear);
     plot->yAxis2->setTicker(linTicker);
     plot->yAxis2->setNumberFormat("f");
+    plot->yAxis2->setVisible(true);
 
     graph1->setName("Real");
     graph2->setName("Imaginary");
+    graph2->setVisible(true);
+    graph3->setVisible(true);
     
     plot->replot();
 }
 
-void GraphWidget::addData(double freq, double val1, double val2) {
+void GraphWidget::configureNyquistPlot() {
-    // 1. Validate X-Axis (Frequency)
+    clear();
-    // If Log scale, Frequency must be > 0.
+    
-    if (plot->xAxis->scaleType() == QCPAxis::stLogarithmic && freq <= 0) {
+    // X Axis: Real (Z')
-        return; 
+    plot->xAxis->setLabel("Real (Z')");
+    plot->xAxis->setScaleType(QCPAxis::stLinear);
+    QSharedPointer<QCPAxisTicker> linTicker(new QCPAxisTicker);
+    plot->xAxis->setTicker(linTicker);
+    plot->xAxis->setNumberFormat("f");
+    
+    // Y Axis 1: -Imaginary (-Z'')
+    plot->yAxis->setLabel("-Imaginary (-Z'')");
+    plot->yAxis->setScaleType(QCPAxis::stLinear);
+    plot->yAxis->setTicker(linTicker);
+    plot->yAxis->setNumberFormat("f");
+
+    // Disable Secondary Axis for Nyquist
+    plot->yAxis2->setVisible(false);
+    graph2->setVisible(false);
+    graph3->setVisible(false);
+
+    graph1->setName("Nyquist");
+    graph1->setLineStyle(QCPGraph::lsLine);
+    graph1->setScatterStyle(QCPScatterStyle(QCPScatterStyle::ssCircle, 4));
+    
+    plot->replot();
 }
 
-    // 2. Validate Y-Axis 1 (Impedance/Real)
+void GraphWidget::addData(double x, double val1, double val2) {
-    // If Log scale (Impedance), value must be > 0.
+    // Mode Detection based on Axis Labels (Simple state check)
-    if (plot->yAxis->scaleType() == QCPAxis::stLogarithmic) {
+    bool isNyquist = (plot->xAxis->label() == "Real (Z')");
-        // If we have a zero/negative impedance in log mode, skip it.
+
-        // Clamping to 1e-12 causes massive axis scaling issues (squished plots).
+    if (isNyquist) {
-        if (val1 <= 1e-7) { 
+        // For Nyquist: x = Real, val1 = Imaginary
-             val1 = std::numeric_limits<double>::quiet_NaN();
+        // We plot Real vs -Imaginary
-        }
+        graph1->addData(x, -val1); 
+    } else {
+        // Raw Plot: x = Freq, val1 = Real, val2 = Imag
+        if (plot->xAxis->scaleType() == QCPAxis::stLogarithmic && x <= 0) return;
+        
+        graph1->addData(x, val1);
+        graph2->addData(x, val2);
     }
 
-    // 3. Add Data
+    // Auto-scale
-    // QCustomPlot handles NaN by creating a line gap, which is visually correct for missing/bad data.
-    if (!std::isnan(val1)) {
-        graph1->addData(freq, val1);
-    }
-    
-    // Graph 2 (Phase/Imag) is usually Linear.
-    graph2->addData(freq, val2);
-
-    // 4. Auto-scale
-    // We remove 'true' (onlyEnlarge). We want the axes to shrink 
-    // if we zoom in or if the data range stabilizes.
     graph1->rescaleAxes(false); 
+    if (!isNyquist) {
         graph2->rescaleAxes(false); 
+        graph3->rescaleAxes(false);
+    }
     
     plot->replot();
 }
 
+void GraphWidget::addHilbertData(const QVector<double>& freq, const QVector<double>& hilbertImag) {
+    // Only valid for Raw Plot
+    if (plot->xAxis->label() != "Frequency (Hz)") return;
+
+    graph3->setData(freq, hilbertImag);
+    graph3->rescaleAxes(false);
+    plot->replot();
+}
+
 void GraphWidget::clear() {
     graph1->data()->clear();
     graph2->data()->clear();
+    graph3->data()->clear();
     plot->replot();
 }

host/src/GraphWidget.h

@@ -1,3 +1,4 @@
+// File: host/src/GraphWidget.h
 #pragma once
 
 #include <QWidget>
@@ -12,15 +13,17 @@ public:
     
     // Data Handling
     void addData(double freq, double val1, double val2);
+    void addHilbertData(const QVector<double>& freq, const QVector<double>& hilbertImag);
     void clear();
     
     // View Configurations
-    void configureBodePlot();
     void configureRawPlot();
+    void configureNyquistPlot();
 
 private:
     QVBoxLayout *layout;
     QCustomPlot *plot;
-    QCPGraph *graph1;
+    QCPGraph *graph1; // Real
-    QCPGraph *graph2;
+    QCPGraph *graph2; // Imaginary
+    QCPGraph *graph3; // Hilbert (Analytic Imaginary)
 };

host/src/MainWindow.cpp

@@ -1,4 +1,4 @@
-// host/src/MainWindow.cpp
+// File: host/src/MainWindow.cpp
 #include "MainWindow.h"
 #include <QVBoxLayout>
 #include <QDebug>
@@ -10,6 +10,44 @@
 #include <QLabel>
 #include <QTimer>
 #include <cmath>
+#include <complex>
+#include <vector>
+
+// Simple FFT Implementation (Cooley-Tukey)
+// Note: Size must be power of 2
+void fft(std::vector<std::complex<double>>& a) {
+    int n = a.size();
+    if (n <= 1) return;
+
+    std::vector<std::complex<double>> a0(n / 2), a1(n / 2);
+    for (int i = 0; i < n / 2; i++) {
+        a0[i] = a[2 * i];
+        a1[i] = a[2 * i + 1];
+    }
+    fft(a0);
+    fft(a1);
+
+    double ang = 2 * M_PI / n;
+    std::complex<double> w(1), wn(cos(ang), sin(ang));
+    for (int i = 0; i < n / 2; i++) {
+        a[i] = a0[i] + w * a1[i];
+        a[i + n / 2] = a0[i] - w * a1[i];
+        w *= wn;
+    }
+}
+
+void ifft(std::vector<std::complex<double>>& a) {
+    int n = a.size();
+    // Conjugate
+    for (int i = 0; i < n; i++) a[i] = std::conj(a[i]);
+    // Forward FFT
+    fft(a);
+    // Conjugate again and scale
+    for (int i = 0; i < n; i++) {
+        a[i] = std::conj(a[i]);
+        a[i] /= n;
+    }
+}
 
 MainWindow::MainWindow(QWidget *parent) : QMainWindow(parent) {
     serial = new QSerialPort(this);
@@ -37,13 +75,16 @@ void MainWindow::setupUi() {
 
     // Tab Widget for Graphs
     tabWidget = new QTabWidget(this);
-    finalGraph = new GraphWidget(this);
+    
-    finalGraph->configureBodePlot();
     rawGraph = new GraphWidget(this);
     rawGraph->configureRawPlot();
     
-    tabWidget->addTab(finalGraph, "Bode Plot");
+    nyquistGraph = new GraphWidget(this);
+    nyquistGraph->configureNyquistPlot();
+
+    // Raw Data is now Default (Index 0)
     tabWidget->addTab(rawGraph, "Raw Data");
+    tabWidget->addTab(nyquistGraph, "Nyquist Plot");
 
     // Log Widget
     logWidget = new QTextEdit(this);
@@ -211,8 +252,12 @@ void MainWindow::runCalibration() {
 void MainWindow::startSweep() {
     if (!serial->isOpen()) return;
     
-    finalGraph->clear();
     rawGraph->clear();
+    nyquistGraph->clear();
+    
+    // Clear accumulated data
+    sweepFreqs.clear();
+    sweepReals.clear();
     
     // Use Firmware Sweep Command: s <start> <end> <steps>
     // Example: 100Hz to 200kHz, 50 steps
@@ -260,15 +305,69 @@ void MainWindow::parseData(const QString &data) {
     QStringList parts = data.split(',');
     if (parts.size() < 6) return;
 
-    bool okF, okM, okP, okR, okI;
+    bool okF, okR, okI;
     double freq = parts[1].toDouble(&okF);
-    double mag  = parts[2].toDouble(&okM);
-    double phase= parts[3].toDouble(&okP);
     double real = parts[4].toDouble(&okR);
     double imag = parts[5].toDouble(&okI);
 
-    if (okF && okM && okP) finalGraph->addData(freq, mag, phase);
+    if (okF && okR && okI) {
-    if (okF && okR && okI) rawGraph->addData(freq, real, imag);
+        // Add to Raw Graph (Freq vs Real/Imag)
+        rawGraph->addData(freq, real, imag);
+        
+        // Add to Nyquist Graph (Real vs Imag)
+        nyquistGraph->addData(real, imag, 0); 
+        
+        // Accumulate for Hilbert
+        sweepFreqs.append(freq);
+        sweepReals.append(real);
+        
+        // Check if sweep is done (e.g., 50 points)
+        // For now, update Hilbert every 10 points or at end
+        if (sweepReals.size() >= 50) {
+            computeHilbert();
+        }
+    }
+}
+
+void MainWindow::computeHilbert() {
+    int n = sweepReals.size();
+    if (n == 0) return;
+
+    // 1. Zero-pad to next power of 2
+    int n_fft = 1;
+    while (n_fft < n) n_fft *= 2;
+    
+    std::vector<std::complex<double>> signal(n_fft);
+    for (int i = 0; i < n; i++) {
+        signal[i] = std::complex<double>(sweepReals[i], 0.0);
+    }
+
+    // 2. FFT
+    fft(signal);
+
+    // 3. Create Analytic Signal in Frequency Domain
+    // H[0] = H[0]
+    // H[i] = 2*H[i] for 0 < i < N/2
+    // H[N/2] = H[N/2]
+    // H[i] = 0 for N/2 < i < N
+    for (int i = 1; i < n_fft / 2; i++) {
+        signal[i] *= 2.0;
+    }
+    for (int i = n_fft / 2 + 1; i < n_fft; i++) {
+        signal[i] = 0.0;
+    }
+
+    // 4. IFFT
+    ifft(signal);
+
+    // 5. Extract Imaginary Part (Hilbert Transform)
+    QVector<double> hilbertImag;
+    for (int i = 0; i < n; i++) {
+        hilbertImag.append(signal[i].imag());
+    }
+
+    // 6. Plot
+    rawGraph->addHilbertData(sweepFreqs, hilbertImag);
 }
 
 bool MainWindow::event(QEvent *event) {

host/src/MainWindow.h

@@ -1,4 +1,4 @@
-// host/src/MainWindow.h
+// File: host/src/MainWindow.h
 #pragma once
 
 #include <QMainWindow>
@@ -42,12 +42,13 @@ private:
     void setupUi();
     void parseData(const QString &data);
     void handleSwipe(QSwipeGesture *gesture);
+    void computeHilbert();
 
     QSerialPort *serial;
     
     // Views
-    GraphWidget *finalGraph; // Bode Plot
+    GraphWidget *rawGraph;     // Raw Data (Freq vs Real/Imag)
-    GraphWidget *rawGraph;   // Raw Data
+    GraphWidget *nyquistGraph; // Nyquist (Real vs -Imag)
     QTextEdit *logWidget;      // Serial Log
 
     // Layout
@@ -62,4 +63,8 @@ private:
     QDoubleSpinBox *spinFreq;
 
     bool isMeasuring = false;
+    
+    // Data Accumulation for Hilbert
+    QVector<double> sweepFreqs;
+    QVector<double> sweepReals;
 };

main.c

@@ -1,4 +1,4 @@
-// main.c
+// File: main.c
 #include <stdio.h>
 #include <math.h>
 #include <string.h>
@@ -182,28 +182,20 @@ void ImpedanceShowResult(uint32_t *pData, uint32_t DataCount)
 char input_buffer[64];
 int input_pos = 0;
 
-void process_command() {
+// Helper for robust state cleanup
-    char cmd = input_buffer[0];
+void AD5940_Main_Cleanup(void) {
-    AppIMPCfg_Type *pCfg;
+    // Ensure chip is awake before sending commands
-    AppIMPGetCfg(&pCfg);
+    AD5940_WakeUp(10);
 
-    // CRITICAL: Stop any running measurement before reconfiguration
+    // 1. Stop Sequencer and Wakeup Timer
-    AppIMPCtrl(IMPCTRL_STOPNOW, 0);
+    AD5940_WUPTCtrl(bFALSE);
-    sleep_ms(10); // Give AFE time to halt
+    AD5940_SEQCtrlS(bFALSE);
     
-    if (cmd == 'v') {
+    // 2. Stop any active conversions/WG, but KEEP Reference/LDOs ON
-        uint32_t id = AD5940_ReadReg(REG_AFECON_CHIPID);
+    // This prevents settling issues on restart
-        printf("CHIP_ID:0x%04X\n", id);
+    AD5940_AFECtrlS(AFECTRL_ADCCNV|AFECTRL_DFT|AFECTRL_WG, bFALSE);
-    } 
-    else if (cmd == 'c') {
-        // 1. CRITICAL FIX: Force System to 16MHz Low Power Mode
-        // This prevents the 32MHz post-sweep state from corrupting calibration timing
-        AD5940_HPModeEn(bFALSE); 
 
-        // 2. Reset Analog Blocks to ensure clean state
+    // 3. Reset FIFO
-        AD5940_AFECtrlS(AFECTRL_ALL, bFALSE);
-
-        // 3. Disable and Reset the FIFO to stop "DATA" interrupts
     FIFOCfg_Type fifo_cfg;
     fifo_cfg.FIFOEn = bFALSE;           
     AD5940_FIFOCfg(&fifo_cfg);          
@@ -215,8 +207,25 @@ void process_command() {
     fifo_cfg.FIFOThresh = 6;            
     AD5940_FIFOCfg(&fifo_cfg);
     
-        // 4. Clear any pending interrupts
+    // 4. Clear Interrupts
     AD5940_INTCClrFlag(AFEINTSRC_ALLINT);
+}
+
+void process_command() {
+    char cmd = input_buffer[0];
+    AppIMPCfg_Type *pCfg;
+    AppIMPGetCfg(&pCfg);
+
+    // CRITICAL: Perform robust cleanup before any new operation
+    AD5940_Main_Cleanup();
+    sleep_ms(10); // Give AFE time to settle
+
+    if (cmd == 'v') {
+        uint32_t id = AD5940_ReadReg(REG_AFECON_CHIPID);
+        printf("CHIP_ID:0x%04X\n", id);
+    } 
+    else if (cmd == 'c') {
+        // Cleanup already done by AD5940_Main_Cleanup() above
 
         // 5. Perform ADC Calibration (Offset)
         ADCPGACal_Type adcpga_cal;
@@ -282,7 +291,11 @@ void process_command() {
         pCfg->SweepCfg.SweepEn = bFALSE;
         pCfg->SinFreq = freq;
         pCfg->NumOfData = -1; // Continuous
-        pCfg->bParaChanged = bTRUE; // Force sequence regeneration
+        
+        // CRITICAL FIX: Force parameter change flag to TRUE.
+        // This ensures AppIMPInit calls AppIMPSeqCfgGen, which re-enables
+        // the analog blocks (DAC, TIA, etc.) that AD5940_Main_Cleanup turned off.
+        pCfg->bParaChanged = bTRUE; 
         
         if(AppIMPInit(AppBuff, APPBUFF_SIZE) == AD5940ERR_OK) {
             AppIMPCtrl(IMPCTRL_START, 0);
@@ -302,7 +315,9 @@ void process_command() {
         pCfg->SweepCfg.SweepPoints = steps;
         pCfg->SweepCfg.SweepLog = bTRUE;
         pCfg->NumOfData = steps; // Stop after sweep
-        pCfg->bParaChanged = bTRUE; // Force sequence regeneration
+        
+        // CRITICAL FIX: Force parameter change flag to TRUE.
+        pCfg->bParaChanged = bTRUE; 
         
         if(AppIMPInit(AppBuff, APPBUFF_SIZE) == AD5940ERR_OK) {
             AppIMPCtrl(IMPCTRL_START, 0);
@@ -312,7 +327,7 @@ void process_command() {
     }
     else if (cmd == 'x') {
         // Stop Measurement
-        AppIMPCtrl(IMPCTRL_STOPNOW, 0);
+        // Cleanup already done by AD5940_Main_Cleanup() at start of function
         printf("STOPPED\n");
     }
     else if (cmd == 'z') {
@@ -348,6 +363,14 @@ int main() {
             AppIMPISR(AppBuff, &temp);
             if(temp > 0) {
                 ImpedanceShowResult(AppBuff, temp);
+                
+                // Check if sweep is done (simple check based on config)
+                AppIMPCfg_Type *pCfg;
+                AppIMPGetCfg(&pCfg);
+                if (pCfg->SweepCfg.SweepEn && pCfg->FifoDataCount >= pCfg->NumOfData) {
+                    printf("DONE\n");
+                    AD5940_Main_Cleanup(); // Ensure clean stop
+                }
             }
         }
     }