Add per-channel independent limit controls

- Separate Lim A / Lim B trackbars (0-200, default 30 each)
- Separate Scale A / Scale B checkboxes (clamp vs scale per channel)
- State.SetLimitA/SetLimitB with independent LimitModeA/LimitModeB
- ConsumeTick applies per-channel limit and mode

HeatMap.cs

@@ -0,0 +1,109 @@
+using System.Drawing.Drawing2D;
+
+namespace Substation;
+
+public class HeatMap : Panel
+{
+    record Tick(byte[] Freq, byte[] Intensity);
+
+    readonly List<Tick> _history = new();
+    readonly int _maxTicks;
+
+    public HeatMap(int maxTicks = 60)
+    {
+        _maxTicks = maxTicks;
+        DoubleBuffered = true;
+        BackColor = Color.FromArgb(20, 20, 22);
+    }
+
+    public void AddTick(byte[] freq, byte[] intensity, bool active)
+    {
+        if (_history.Count >= _maxTicks)
+            _history.RemoveAt(0);
+
+        if (active)
+            _history.Add(new Tick(freq, intensity));
+        else
+            _history.Add(new Tick(Array.Empty<byte>(), Array.Empty<byte>()));
+
+        Invalidate();
+    }
+
+    protected override void OnPaint(PaintEventArgs e)
+    {
+        base.OnPaint(e);
+        var g = e.Graphics;
+        g.SmoothingMode = SmoothingMode.None;
+
+        int w = Width;
+        int h = Height;
+        int colW = Math.Max(1, w / _maxTicks);
+
+        // Draw axis labels
+        using var font = new Font(FontFamily.GenericMonospace, 7);
+        using var textBrush = new SolidBrush(Color.FromArgb(100, 100, 100));
+        g.DrawString("100Hz", font, textBrush, 2, 2);
+        g.DrawString("1Hz", font, textBrush, 2, h - 14);
+
+        int plotX = 36;
+        int plotW = w - plotX - 4;
+        int plotH = h - 4;
+        colW = Math.Max(1, plotW / _maxTicks);
+
+        for (int i = 0; i < _history.Count; i++)
+        {
+            var tick = _history[i];
+            int xPos = plotX + i * colW;
+
+            if (tick.Freq.Length == 0)
+            {
+                // Inactive — dark cell
+                using var dark = new SolidBrush(Color.FromArgb(25, 25, 28));
+                g.FillRectangle(dark, xPos, 2, colW, plotH);
+                continue;
+            }
+
+            // 4 sub-ticks side by side within the column
+            int subW = Math.Max(1, colW / 4);
+            for (int s = 0; s < 4; s++)
+            {
+                int freq = tick.Freq[s];   // 10-240
+                int inten = tick.Intensity[s]; // 0-100
+                if (inten > 100) inten = 0; // 101 sentinel = off
+
+                // Map freq byte (10-240) to Y position (top=high freq, bottom=low freq)
+                float normFreq = (freq - 10f) / (240f - 10f);
+                int y = (int)(2 + plotH * (1f - normFreq));
+                if (y < 2) y = 2;
+                if (y > plotH) y = plotH;
+
+                var color = HeatColor(inten);
+                using var brush = new SolidBrush(color);
+                g.FillRectangle(brush, xPos + s * subW, y, subW, 3);
+            }
+        }
+    }
+
+    static Color HeatColor(int intensity)
+    {
+        // 0=black, 30=blue, 60=green, 80=gold, 100=red
+        if (intensity <= 0) return Color.FromArgb(20, 20, 22);
+        if (intensity < 30)
+        {
+            float t = intensity / 30f;
+            return Color.FromArgb(0, (int)(50 * t), (int)(80 + 80 * t));
+        }
+        if (intensity < 60)
+        {
+            float t = (intensity - 30) / 30f;
+            return Color.FromArgb((int)(60 * t), (int)(130 + 80 * t), (int)(160 - 100 * t));
+        }
+        if (intensity < 80)
+        {
+            float t = (intensity - 60) / 20f;
+            return Color.FromArgb((int)(60 + 180 * t), 210, (int)(60 - 30 * t));
+        }
+        float t2 = (intensity - 80) / 20f;
+        return Color.FromArgb(255, (int)(240 - 140 * t2), (int)(30 - 10 * t2));
+    }
+}

MainForm.cs

@@ -24,17 +24,20 @@ public class MainForm : Form
 
     bool _closingFromTray;
 
-    readonly ProgressBar _gaugeSendA;
+    readonly HeatMap _heatA;
-    readonly ProgressBar _gaugeSendB;
+    readonly HeatMap _heatB;
     readonly ProgressBar _gaugeRecvA;
     readonly ProgressBar _gaugeRecvB;
     readonly Label _lblSendA;
     readonly Label _lblSendB;
     readonly Label _lblRecvA;
     readonly Label _lblRecvB;
-    readonly TrackBar _limitBar;
+    readonly TrackBar _limitBarA;
-    readonly Label _lblLimit;
+    readonly TrackBar _limitBarB;
-    readonly CheckBox _chkScale;
+    readonly Label _lblLimitA;
+    readonly Label _lblLimitB;
+    readonly CheckBox _chkScaleA;
+    readonly CheckBox _chkScaleB;
 
     readonly Icon _iconNeutral;
     readonly Icon _iconActive;
@@ -55,7 +58,7 @@ public class MainForm : Form
         _loopCts = new CancellationTokenSource();
 
         Text = $"Substation {typeof(MainForm).Assembly.GetName().Version}";
-        ClientSize = new Size(420, 360);
+        ClientSize = new Size(420, 410);
         FormBorderStyle = FormBorderStyle.FixedSingle;
         MaximizeBox = false;
         StartPosition = FormStartPosition.CenterScreen;
@@ -137,39 +140,33 @@ public class MainForm : Form
             Size = new Size(48, 20),
             Font = new Font(Font.FontFamily, 9, FontStyle.Bold)
         };
-        _gaugeSendA = new ProgressBar
+        _heatA = new HeatMap(60)
         {
-            Location = new Point(72, 160),
+            Location = new Point(72, 158),
-            Size = new Size(332, 20),
+            Size = new Size(332, 22)
-            Minimum = 0,
-            Maximum = 100,
-            Style = ProgressBarStyle.Continuous
         };
         _lblSendB = new Label
         {
             Text = "Send B",
-            Location = new Point(16, 184),
+            Location = new Point(16, 188),
             Size = new Size(48, 20),
             Font = new Font(Font.FontFamily, 9, FontStyle.Bold)
         };
-        _gaugeSendB = new ProgressBar
+        _heatB = new HeatMap(60)
         {
-            Location = new Point(72, 184),
+            Location = new Point(72, 186),
-            Size = new Size(332, 20),
+            Size = new Size(332, 22)
-            Minimum = 0,
-            Maximum = 100,
-            Style = ProgressBarStyle.Continuous
         };
         _lblRecvA = new Label
         {
             Text = "Recv A",
-            Location = new Point(16, 212),
+            Location = new Point(16, 216),
             Size = new Size(48, 20),
             Font = new Font(Font.FontFamily, 9, FontStyle.Bold)
         };
         _gaugeRecvA = new ProgressBar
         {
-            Location = new Point(72, 212),
+            Location = new Point(72, 216),
             Size = new Size(332, 20),
             Minimum = 0,
             Maximum = 200,
@@ -178,47 +175,73 @@ public class MainForm : Form
         _lblRecvB = new Label
         {
             Text = "Recv B",
-            Location = new Point(16, 236),
+            Location = new Point(16, 242),
             Size = new Size(48, 20),
             Font = new Font(Font.FontFamily, 9, FontStyle.Bold)
         };
         _gaugeRecvB = new ProgressBar
         {
-            Location = new Point(72, 236),
+            Location = new Point(72, 242),
             Size = new Size(332, 20),
             Minimum = 0,
             Maximum = 200,
             Style = ProgressBarStyle.Continuous
         };
 
-        _lblLimit = new Label
+        _lblLimitA = new Label
         {
-            Text = "Limit: 30",
+            Text = "Lim A: 30",
-            Location = new Point(16, 272),
+            Location = new Point(16, 274),
-            Size = new Size(64, 20),
+            Size = new Size(56, 20),
             Font = new Font(Font.FontFamily, 9, FontStyle.Bold)
         };
-        _limitBar = new TrackBar
+        _limitBarA = new TrackBar
         {
-            Location = new Point(80, 268),
+            Location = new Point(72, 270),
-            Size = new Size(240, 45),
+            Size = new Size(250, 45),
             Minimum = 0,
             Maximum = 200,
             TickFrequency = 50,
             Value = 30
         };
-        _limitBar.ValueChanged += OnLimitChanged;
+        _limitBarA.ValueChanged += OnLimitChanged;
-        _chkScale = new CheckBox
+        _chkScaleA = new CheckBox
         {
             Text = "Scale",
-            Location = new Point(328, 272),
+            Location = new Point(328, 274),
             Size = new Size(76, 24),
             Checked = false
         };
-        _chkScale.CheckedChanged += OnLimitChanged;
+        _chkScaleA.CheckedChanged += OnLimitChanged;
+
+        _lblLimitB = new Label
+        {
+            Text = "Lim B: 30",
+            Location = new Point(16, 312),
+            Size = new Size(56, 20),
+            Font = new Font(Font.FontFamily, 9, FontStyle.Bold)
+        };
+        _limitBarB = new TrackBar
+        {
+            Location = new Point(72, 308),
+            Size = new Size(250, 45),
+            Minimum = 0,
+            Maximum = 200,
+            TickFrequency = 50,
+            Value = 30
+        };
+        _limitBarB.ValueChanged += OnLimitChanged;
+        _chkScaleB = new CheckBox
+        {
+            Text = "Scale",
+            Location = new Point(328, 312),
+            Size = new Size(76, 24),
+            Checked = false
+        };
+        _chkScaleB.CheckedChanged += OnLimitChanged;
         OnLimitChanged(null, EventArgs.Empty);
 
-        Controls.AddRange(new Control[] { _lblBle, _lblWs, _lblDeviceName, _txtDeviceName, _btnConnect, _btnTest, _btnMusic, _btnStop, _lblTrack, _lblSendA, _gaugeSendA, _lblSendB, _gaugeSendB, _lblRecvA, _gaugeRecvA, _lblRecvB, _gaugeRecvB, _lblLimit, _limitBar, _chkScale });
+        Controls.AddRange(new Control[] { _lblBle, _lblWs, _lblDeviceName, _txtDeviceName, _btnConnect, _btnTest, _btnMusic, _btnStop, _lblTrack, _lblSendA, _heatA, _lblSendB, _heatB, _lblRecvA, _gaugeRecvA, _lblRecvB, _gaugeRecvB, _lblLimitA, _limitBarA, _chkScaleA, _lblLimitB, _limitBarB, _chkScaleB });
 
         // Tray icon — three cached variants: neutral=gray, active=gold, hot=red-orange
         _iconNeutral = CreateVoltageIcon(Color.Gray);
@@ -357,8 +380,14 @@ public class MainForm : Form
         _lblBle.Text = _device.IsConnected
             ? $"BLE: connected ({_device.DeviceName})"
             : "BLE: disconnected";
-        _gaugeSendA.Value = Math.Clamp(_state.LastIntensityA, 0, 100);
+        _heatA.AddTick(
-        _gaugeSendB.Value = Math.Clamp(_state.LastIntensityB, 0, 100);
+            _state.LastFreqA ?? Array.Empty<byte>(),
+            _state.LastIntA ?? Array.Empty<byte>(),
+            _state.LastActiveA);
+        _heatB.AddTick(
+            _state.LastFreqB ?? Array.Empty<byte>(),
+            _state.LastIntB ?? Array.Empty<byte>(),
+            _state.LastActiveB);
         _gaugeRecvA.Value = Math.Clamp(_device.StrengthA, 0, 200);
         _gaugeRecvB.Value = Math.Clamp(_device.StrengthB, 0, 200);
         _btnTest.Enabled = !_server.HasClient && !IsTestRunning;
@@ -443,10 +472,14 @@ public class MainForm : Form
 
     void OnLimitChanged(object? sender, EventArgs e)
     {
-        var max = _limitBar.Value;
+        var maxA = _limitBarA.Value;
-        var mode = _chkScale.Checked ? LimitMode.Scale : LimitMode.Clamp;
+        var maxB = _limitBarB.Value;
-        _state.SetLimit(max, mode);
+        var modeA = _chkScaleA.Checked ? LimitMode.Scale : LimitMode.Clamp;
-        _lblLimit.Text = $"Limit: {max}";
+        var modeB = _chkScaleB.Checked ? LimitMode.Scale : LimitMode.Clamp;
+        _state.SetLimitA(maxA, modeA);
+        _state.SetLimitB(maxB, modeB);
+        _lblLimitA.Text = $"Lim A: {maxA}";
+        _lblLimitB.Text = $"Lim B: {maxB}";
     }
 
     string _musicFilePath = "";

State.cs

@@ -18,17 +18,30 @@ public class State
     public int ActualA, ActualB;
     public int LastSentA, LastSentB;
     public int LastIntensityA, LastIntensityB;
+    public byte[]? LastFreqA, LastIntA, LastFreqB, LastIntB;
+    public bool LastActiveA, LastActiveB;
 
-    public int MaxStrength = 200;
+    public int MaxA = 200;
-    public LimitMode LimitMode = LimitMode.Clamp;
+    public int MaxB = 200;
+    public LimitMode LimitModeA = LimitMode.Clamp;
+    public LimitMode LimitModeB = LimitMode.Clamp;
 
-    public void SetLimit(int max, LimitMode mode)
+    public void SetLimitA(int max, LimitMode mode)
     {
         lock (Lock)
         {
-            MaxStrength = Math.Clamp(max, 0, 200);
+            MaxA = Math.Clamp(max, 0, 200);
-            LimitMode = mode;
+            LimitModeA = mode;
             DirtyA = true;
+        }
+    }
+
+    public void SetLimitB(int max, LimitMode mode)
+    {
+        lock (Lock)
+        {
+            MaxB = Math.Clamp(max, 0, 200);
+            LimitModeB = mode;
             DirtyB = true;
         }
     }
@@ -93,14 +106,12 @@ public class State
             var modeA = DirtyA ? StrengthMode.Abs : StrengthMode.None;
             var modeB = DirtyB ? StrengthMode.Abs : StrengthMode.None;
 
-            var limit = MaxStrength;
+            byte ApplyLimit(int desired, int max, LimitMode mode) =>
-            var limMode = LimitMode;
+                mode == LimitMode.Scale
-            byte ApplyLimit(int desired) =>
+                    ? (byte)(desired * max / 200)
-                limMode == LimitMode.Scale
+                    : (byte)Math.Clamp(desired, 0, max);
-                    ? (byte)(desired * limit / 200)
+            var valA  = ApplyLimit(DesiredA, MaxA, LimitModeA);
-                    : (byte)Math.Clamp(desired, 0, limit);
+            var valB  = ApplyLimit(DesiredB, MaxB, LimitModeB);
-            var valA  = ApplyLimit(DesiredA);
-            var valB  = ApplyLimit(DesiredB);
             LastSentA = valA;
             LastSentB = valB;
             DirtyA = false;
@@ -111,6 +122,10 @@ public class State
             var (freqA, intA) = PopWave(StreamA, LoopFreqA, LoopIntA);
             var (freqB, intB) = PopWave(StreamB, LoopFreqB, LoopIntB);
 
+            LastActiveA = hasA;
+            LastActiveB = hasB;
+            LastFreqA = freqA; LastIntA = intA;
+            LastFreqB = freqB; LastIntB = intB;
             LastIntensityA = hasA ? (intA[0] + intA[1] + intA[2] + intA[3]) / 4 : 0;
             LastIntensityB = hasB ? (intB[0] + intB[1] + intB[2] + intB[3]) / 4 : 0;