finished basic oscilloscope functionalities (max sampling rate seems to be 38KHz)

OneWireIO.ino

@@ -5,12 +5,14 @@
 #define OWPin     2
 #define InterruptNumber 0 // Must correspond to the OWPin to correctly detect state changes. On Arduino Uno, interrupt 0 is for digital pin 2
 
-const int SkipSamples = 8; // how many samples we want to skip between two samples we keep (can be used to lower the sampling frequency)
+// how many samples we want to skip between two samples we keep (can be used to lower the sampling frequency)
-const int BufferSize = 128;
+#define SkipSamples 0
+
+const int BufferSize = 512;
 byte buffer1[BufferSize];
 byte buffer2[BufferSize];
 byte* backBuffer = buffer1;
-volatile byte backBufferPos = 0;
+volatile short backBufferPos = 0;
 byte samplesSkipped = SkipSamples;
 unsigned long backBufferStartTime = micros();
 
@@ -24,7 +26,7 @@ void setup()
 
     digitalWrite(LEDPin, LOW);
 
-    attachInterrupt(InterruptNumber,onewireInterrupt,CHANGE);
+    //attachInterrupt(InterruptNumber,onewireInterrupt,CHANGE);
     
     cli();//disable interrupts
   
@@ -36,7 +38,7 @@ void setup()
     ADMUX |= (1 << REFS0); //set reference voltage
     ADMUX |= (1 << ADLAR); //left align the ADC value- so we can read highest 8 bits from ADCH register only
     
-    ADCSRA |= (1 << ADPS2) | (1 << ADPS1) | (1 << ADPS0); //set ADC clock with 128 prescaler- 16mHz/128=125kHz ; 13 cycles for a conversion which means 9600 samples per second
+    ADCSRA |= (1 << ADPS2) | (0 << ADPS1) | (1 << ADPS0); //set ADC clock with 32 prescaler- 16mHz/32=500KHz ; 13 cycles for a conversion which means 38000 samples per second
     ADCSRA |= (1 << ADATE); //enabble auto trigger
     ADCSRA |= (1 << ADIE); //enable interrupts when measurement complete
     ADCSRA |= (1 << ADEN); //enable ADC
@@ -44,7 +46,7 @@ void setup()
     
     sei();//enable interrupts
     
-    Serial.begin(200000);
+    Serial.begin(400000);
 }
 
 void loop()
@@ -52,27 +54,32 @@ void loop()
     while(backBufferPos < BufferSize / 2) ;
     cli();//disable interrupts
     byte* currentBuffer = backBuffer;
-    unsigned long currentBufferStartTime = backBufferStartTime;
+    short currentBufferSize = backBufferPos;
-    byte currentBufferSize = backBufferPos;
     backBuffer = (backBuffer == buffer1 ? buffer2 : buffer1);
     backBufferPos = 0;
-    backBufferStartTime = micros();
     sei();//enable interrupts
+    unsigned long currentBufferStartTime = backBufferStartTime;
+    backBufferStartTime = micros();
+    digitalWrite(LEDPin, LOW);
     
+    //Serial.write(currentBuffer, currentBufferSize);
     oscilloscope.write(currentBuffer, currentBufferSize, currentBufferStartTime);
 }
 
 ISR(ADC_vect) {//when new ADC value ready
     byte sample = ADCH; //store 8 bit value from analog pin 0
     
+    #if SkipSamples > 0
     if(samplesSkipped++ < SkipSamples)
         return;
     samplesSkipped = 0;
+    #endif
 
     backBuffer[backBufferPos++] = sample;
     if(backBufferPos >= BufferSize)
     {
         // overflow of back buffer, we loose the current sample
+        digitalWrite(LEDPin, HIGH);
         backBufferPos = BufferSize - 1;
     }
 }

SerialMonitor/SerialMonitor/App.xaml.cs

@@ -28,7 +28,7 @@ namespace SerialMonitor
 
             Serial = new SerialPort();
             Serial.PortName = "COM4";
-            Serial.BaudRate = 200000;
+            Serial.BaudRate = 400000;
 
             Serial.DataReceived += new System.IO.Ports.SerialDataReceivedEventHandler(OnDataReceived);
 

SerialMonitor/SerialMonitor/MainWindow.xaml

@@ -1,11 +1,18 @@
 <Window x:Class="SerialMonitor.MainWindow"
         xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
         xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
-        Title="Serial Monitor" Height="396" Width="629">
+        Title="Serial Monitor" Height="490.75" Width="923">
     <Grid>
-        <TextBlock TextWrapping="Wrap" VerticalAlignment="Bottom" Height="150" Text="{Binding ConsoleText}" Style="{DynamicResource Console}" Grid.ColumnSpan="2"/>
+        <Grid.RowDefinitions>
-        <ScrollViewer HorizontalScrollBarVisibility="Visible" Margin="0,0,0,155" Grid.ColumnSpan="2">
+            <RowDefinition Height="290" />
-            <Canvas Name="Oscilloscope" Style="{DynamicResource Oscilloscope}"/>
+            <RowDefinition Height="5" />
+            <RowDefinition Height="*" />
+        </Grid.RowDefinitions>
+        <Canvas Name="Oscilloscope" Style="{DynamicResource Oscilloscope}" Margin="0,0,0,17" />
+        <ScrollBar Grid.Row="0" Orientation="Horizontal" HorizontalAlignment="Stretch" Height="17" VerticalAlignment="Bottom" Minimum="{Binding MinTime}" Maximum="{Binding MaxTime}" ViewportSize="{Binding ViewportTimeWidth}" Value="{Binding ScrollValue}"/>
+        <GridSplitter Grid.Row="1" Height="5" HorizontalAlignment="Stretch" />
+        <ScrollViewer Grid.Row="2">
+            <TextBlock TextWrapping="Wrap" Style="{DynamicResource Console}"  Text="{Binding ConsoleText}"/>
         </ScrollViewer>
     </Grid>
 </Window>

SerialMonitor/SerialMonitor/MainWindow.xaml.cs

@@ -26,6 +26,37 @@ namespace SerialMonitor
             var context = new MainWindowContext(this);
             context.WriteLine("Connecting...");
             this.DataContext = context;
+
+            this.MouseWheel += OnMouseWheel;
+        }
+
+        private void OnMouseWheel(object sender, MouseWheelEventArgs e)
+        {
+            MainWindowContext context = (MainWindowContext)this.DataContext;
+            Point cursorPos = e.GetPosition(context.OscilloscopeCanvas);
+            if (cursorPos.X < 0 || cursorPos.X > context.OscilloscopeCanvas.ActualWidth || cursorPos.Y < 0 || cursorPos.Y > context.OscilloscopeCanvas.ActualHeight)
+                return;
+
+            double cursorPosRatio = cursorPos.X / context.OscilloscopeCanvas.ActualWidth;
+            double cursorTime = context.ViewportStartTime + cursorPosRatio * context.ViewportTimeWidth;
+
+            double newTimeWidth = context.ViewportTimeWidth;
+            if (e.Delta > 0)
+                newTimeWidth /= e.Delta * 0.01;
+            else if (e.Delta < 0)
+                newTimeWidth *= -e.Delta * 0.01;
+
+            double totalTimeWidth = Math.Max(0.1, context.MaxTime - context.MinTime);
+            if (newTimeWidth > totalTimeWidth)
+                newTimeWidth = totalTimeWidth;
+
+            double newStartTime = cursorTime - cursorPosRatio * newTimeWidth;
+            if (newStartTime < context.MinTime)
+                newStartTime = context.MinTime;
+            if (newStartTime + newTimeWidth > context.MaxTime)
+                newStartTime = context.MaxTime - newTimeWidth;
+
+            context.SetViewport(newStartTime, newTimeWidth);
         }
     }
 }

SerialMonitor/SerialMonitor/MainWindowContext.cs

@@ -1,11 +1,13 @@
 using System;
 using System.Collections.Generic;
 using System.ComponentModel;
+using System.Diagnostics;
 using System.Linq;
 using System.Text;
 using System.Threading.Tasks;
 using System.Windows;
 using System.Windows.Controls;
+using System.Windows.Input;
 using System.Windows.Shapes;
 
 namespace SerialMonitor
@@ -28,11 +30,14 @@ namespace SerialMonitor
         public void WriteLine(string line)
         {
             Lines.Add(line);
-            if (Lines.Count > 9)
+            if (Lines.Count > 100)
                 Lines.RemoveAt(0);
             OnPropertyChanged("ConsoleText");
         }
 
+        public double SampleDelay { get { return 0.000026; } }
+        public int MaxSequenceSize { get { return 2048; } }
+
         private class Sequence
         {
             public ulong StartTime { get; set; }
@@ -46,7 +51,11 @@ namespace SerialMonitor
                 }
             }
         }
-        double ValueToHeight(byte value) { return (double)value + 10; }
+        double ValueToHeight(double time, byte value)
+        {
+            //value = (byte)(Math.Sin(time * 100.0) * 127.0 + 128.0);
+            return 256.0 - (double)value + 10;
+        }
         private SortedSet<Sequence> Sequences = new SortedSet<Sequence>(new Sequence.Comparer());
         public IEnumerable<Line> Oscilloscope
         {
@@ -55,63 +64,146 @@ namespace SerialMonitor
                 if(!Sequences.Any())
                     yield break;
                 
-                ulong startTime = Sequences.ElementAt(0).StartTime;
-                
                 foreach (var sequence in Sequences)
                 {
-                    foreach (var line in ConvertToLines(sequence, startTime))
+                    double seqStartTime = (double)sequence.StartTime/1000000.0;
+                    if (seqStartTime + (double)sequence.Data.Length * SampleDelay > ViewportStartTime && seqStartTime < ViewportStartTime + ViewportTimeWidth)
+                    {
+                        foreach (var line in ConvertToLines(sequence))
                             yield return line;
                     }
                 }
             }
+        }
 
-        private IEnumerable<Line> ConvertToLines(Sequence sequence, ulong displayStartTime)
+        private IEnumerable<Line> ConvertToLines(Sequence sequence)
         {
-            double sampleDelay = 0.000936; // in seconds
+            double viewportWidth = OscilloscopeCanvas.ActualWidth;
-            double scale = 10; // in pixels per second
+            double scale = viewportWidth / ViewportTimeWidth; // in pixels per second
 
-            double pos = (sequence.StartTime - displayStartTime) / 1000000.0 * scale;
+            ulong displayStartTime = (ulong)(viewportStartTime_ * 1000000.0);
+
+            double pos = ((double)sequence.StartTime - (double)displayStartTime) / 1000000.0 * scale;
             if (pos > 1000)
                 yield break;
-            double prevHeight = ValueToHeight(sequence.Data[0]);
+            double prevPos = pos;
+            byte minValue = sequence.Data[0];
+            byte maxValue = minValue;
+            int prevIdx = 0;
+            double prevHeight = ValueToHeight(sequence.StartTime / 1000000.0, minValue);
             for (int idx = 1; idx < sequence.Data.Length; ++idx)
             {
                 byte value = sequence.Data[idx];
+                pos += SampleDelay * scale;
+                if (value > maxValue) maxValue = value;
+                if (value < minValue) minValue = value;
+
+                if (pos > 0 && pos < viewportWidth && pos - prevPos >= 5 || idx == sequence.Data.Length - 1)
+                {
                     var line = new Line();
                     line.Stroke = System.Windows.Media.Brushes.LightSteelBlue;
-                line.X1 = pos;
-                pos += sampleDelay * scale;
-                line.X2 = pos;
-                line.Y1 = prevHeight;
-                prevHeight = ValueToHeight(value);
-                line.Y2 = prevHeight;
                     line.HorizontalAlignment = HorizontalAlignment.Left;
                     line.VerticalAlignment = VerticalAlignment.Center;
                     line.StrokeThickness = 1;
+
+                    line.X1 = prevPos;
+                    prevPos = pos;
+                    line.X2 = pos;
+
+                    double time = (double)sequence.StartTime / 1000000.0 + (double)idx * SampleDelay;
+                    double lastHeight = ValueToHeight(time, value);
+
+                    if (idx == prevIdx + 1)
+                    {
+                        line.Y1 = prevHeight;
+                        line.Y2 = lastHeight;
+                    }
+                    else
+                    {
+                        if (value - minValue > maxValue - value)
+                        {
+                            line.Y1 = ValueToHeight(time, minValue);
+                            line.Y2 = ValueToHeight(time, maxValue);
+                        }
+                        else
+                        {
+                            line.Y1 = ValueToHeight(time, maxValue);
+                            line.Y2 = ValueToHeight(time, minValue);
+                        }
+                    }
+
+                    prevHeight = lastHeight;
+                    minValue = value;
+                    maxValue = value;
+                    prevIdx = idx;
+
                     yield return line;
                 }
             }
+        }
 
         public void AddSequence(ulong startTime, byte[] data)
         {
+            // TODO: merge sequences if total size is lower than MaxSequenceSize
             var sequence = new Sequence { StartTime = startTime, Data = data };
             Sequences.Add(sequence);
             OnPropertyChanged("Oscilloscope");
-            var canvas = (Canvas)Window.FindName("Oscilloscope");
+            OnPropertyChanged("MinTime");
-            /*canvas.Children.Clear();
+            OnPropertyChanged("MaxTime");
-            foreach (var line in Oscilloscope)
+            if (Sequences.Count == 1)
-                canvas.Children.Add(line);*/
+            {
-            foreach (var line in ConvertToLines(sequence, Sequences.ElementAt(0).StartTime))
+                ViewportStartTime = MinTime;
+            }
+
+            var canvas = OscilloscopeCanvas;
+            foreach (var line in ConvertToLines(sequence))
                 canvas.Children.Add(line);
         }
 
+        void RefreshOscilloscope()
+        {
+            var canvas = OscilloscopeCanvas;
+            canvas.Children.Clear();
+            foreach (var line in Oscilloscope)
+                canvas.Children.Add(line);
+        }
+
+        private Canvas oscilloscopeCanvas_;
+        public Canvas OscilloscopeCanvas { get { if (oscilloscopeCanvas_ == null) oscilloscopeCanvas_ = (Canvas)Window.FindName("Oscilloscope"); return oscilloscopeCanvas_; } }
+
+        public double MinTime { get { return Sequences.Any() ? (double)Sequences.First().StartTime / 1000000.0 : 0.0; } }
+        public double MaxTime { get { return Sequences.Any() ? Math.Max(MinTime + 0.1, (double)Sequences.Last().StartTime / 1000000.0) : 0.1; } }
+        private double viewportTimeWidth_ = 0.1;
+        public double ViewportTimeWidth
+        {
+            get { return viewportTimeWidth_; }
+            set { viewportTimeWidth_ = value; OnPropertyChanged("ViewportTimeWidth"); RefreshOscilloscope(); }
+        }
+
+        private double viewportStartTime_ = 0;
+        public double ViewportStartTime
+        {
+            get { return viewportStartTime_; }
+            set { viewportStartTime_ = value; OnPropertyChanged("ViewportStartTime"); RefreshOscilloscope(); }
+        }
+        public double ScrollValue
+        {
+            get { return MathEx.Unproject(MathEx.Project(ViewportStartTime, MinTime, MaxTime - ViewportTimeWidth), MinTime, MaxTime); }
+            set { ViewportStartTime = MathEx.Unproject(MathEx.Project(value, MinTime, MaxTime), MinTime, MaxTime - ViewportTimeWidth); }
+        }
+
+        public void SetViewport(double startTime, double timeWidth)
+        {
+            viewportStartTime_ = startTime;
+            ViewportTimeWidth = timeWidth;
+        }
+
         public event PropertyChangedEventHandler PropertyChanged;
         protected void OnPropertyChanged(string name)
         {
-            PropertyChangedEventHandler handler = PropertyChanged;
+            if (PropertyChanged != null)
-            if (handler != null)
             {
-                handler(this, new PropertyChangedEventArgs(name));
+                PropertyChanged(this, new PropertyChangedEventArgs(name));
             }
         }
     }

SerialMonitor/SerialMonitor/MathEx.cs

@@ -0,0 +1,21 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace SerialMonitor
+{
+    public static class MathEx
+    {
+        public static double Project(double value, double rangeMin, double rangeMax)
+        {
+            return (value - rangeMin) / (rangeMax - rangeMin);
+        }
+
+        public static double Unproject(double ratio, double rangeMin, double rangeMax)
+        {
+            return rangeMin + ratio * (rangeMax - rangeMin);
+        }
+    }
+}

SerialMonitor/SerialMonitor/SerialMonitor.csproj

@@ -54,6 +54,7 @@
       <SubType>Designer</SubType>
     </ApplicationDefinition>
     <Compile Include="MainWindowContext.cs" />
+    <Compile Include="MathEx.cs" />
     <Compile Include="SerialMessage.cs" />
     <Compile Include="SerialPortExtensions.cs" />
     <Page Include="MainWindow.xaml">