logicanalyzer/Software/LogicAnalyzer/I2CProtocolAnalyzer/I2CAnalyzer.cs

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9.3 KiB
C#
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2023-02-02 15:45:34 +00:00
using Avalonia.Input.TextInput;
using Avalonia.Media;
using LogicAnalyzer.Protocols;
using Newtonsoft.Json.Linq;
using System.Data;
using System.Text;
namespace I2CProtocolAnalyzer
{
public class I2CAnalyzer : ProtocolAnalyzerBase
{
private SimpleSegmentRenderer renderer = new SimpleSegmentRenderer();
public override string ProtocolName
{
get
{
return "I2C";
}
}
public override ProtocolAnalyzerSetting[] Settings
{
get
{
return new ProtocolAnalyzerSetting[0];
}
}
public override ProtocolAnalyzerSignal[] Signals
{
get
{
return new ProtocolAnalyzerSignal[]
{
new ProtocolAnalyzerSignal{ Required = true, SignalName = "SCL" },
new ProtocolAnalyzerSignal{ Required = true, SignalName = "SDA" },
};
}
}
public override ProtocolAnalyzedChannel[] Analyze(int SamplingRate, int TriggerSample, ProtocolAnalyzerSettingValue[] SelectedSettings, ProtocolAnalyzerSelectedChannel[] SelectedChannels)
{
var scl = SelectedChannels.Where(c => c.SignalName == "SCL").First();
var sda = SelectedChannels.Where(c => c.SignalName == "SDA").First();
List<ProtocolAnalyzerDataSegment> segments = new List<ProtocolAnalyzerDataSegment>();
int startPosition;
int endPosition;
byte value;
bool ack;
bool frameError;
bool foundStartStop;
bool addressByte = true;
bool address10 = false;
byte firstAddressByte = 0;
int pos = FindStartCondition(0, scl, sda, out startPosition, out endPosition);
if (pos == -1)
return new ProtocolAnalyzedChannel[0];
segments.Add(new ProtocolAnalyzerDataSegment { FirstSample = startPosition, LastSample = endPosition, Value = $"START" });
while (pos < sda.Samples.Length)
{
pos = ReadByte(pos, scl, sda, out startPosition, out endPosition, out value, out ack, out frameError);
if (pos == -1)
break;
string asciival = value >= 0x20 && value <= 0x7e ? Encoding.ASCII.GetString(new byte[] { (byte)value }) : "·";
var segment = new ProtocolAnalyzerDataSegment { FirstSample = startPosition, LastSample = endPosition, Value = $"0x{value.ToString()} '{asciival}' <{(ack ? "A" : "N")}{(frameError ? "F" : "")}>" };
if (addressByte)
{
addressByte = false;
segment.Value += $"\r\nOp: {((value & 1) == 1 ? "Read" : "Write") }";
if ((value & 0xf8) == 0xf7)
{
address10 = true;
firstAddressByte = value;
}
else
segment.Value += $"\r\nAddress (7b): 0x{(value >> 1).ToString("X2")}";
}
else if (address10)
{
address10 = false;
segment.Value += $"\r\nAddress (10b): {(((firstAddressByte & 6) << 7) | value).ToString("X4")}";
}
segments.Add(segment);
bool isStart;
pos = FindStartStopCondition(pos, scl, sda, out isStart, out startPosition, out endPosition, out foundStartStop);
if (pos == -1)
break;
if(foundStartStop)
segments.Add(new ProtocolAnalyzerDataSegment { FirstSample = startPosition, LastSample = endPosition, Value = isStart ? "START" : "STOP" });
if (foundStartStop && !isStart)
{
pos = FindStartCondition(pos, scl, sda, out startPosition, out endPosition);
if (pos == -1)
break;
segments.Add(new ProtocolAnalyzerDataSegment { FirstSample = startPosition, LastSample = endPosition, Value = $"START" });
addressByte = true;
}
}
ProtocolAnalyzedChannel channel = new ProtocolAnalyzedChannel("SDA", sda.ChannelIndex, renderer, segments.ToArray(), Colors.White, Color.FromUInt32(0x7f008b8b));
return new ProtocolAnalyzedChannel[] { channel };
}
private int FindStartStopCondition(int pos, ProtocolAnalyzerSelectedChannel scl, ProtocolAnalyzerSelectedChannel sda, out bool isStart, out int startPosition, out int endPosition, out bool found)
{
int initialPosition = pos;
isStart = false;
startPosition = 0;
endPosition = 0;
found = false;
while (pos < scl.Samples.Length && scl.Samples[pos] != 1)
pos++;
if (pos >= scl.Samples.Length)
return -1;
startPosition = pos;
byte val = sda.Samples[pos];
//Initial state will indicate if this may be an start or an stop
isStart = val == 1;
while (pos < scl.Samples.Length && scl.Samples[pos] == 1)
{
if (val != sda.Samples[pos])
{
found = true;
break;
}
pos++;
}
if (pos >= scl.Samples.Length)
return -1;
if (!found)
return initialPosition;
endPosition = pos - 1;
return pos;
}
private int FindStartCondition(int pos, ProtocolAnalyzerSelectedChannel scl, ProtocolAnalyzerSelectedChannel sda, out int startPosition, out int endPosition)
{
startPosition = 0; endPosition = 0;
while (pos < scl.Samples.Length)
{
while (pos < scl.Samples.Length && scl.Samples[pos] != 1)
pos++;
if (pos >= scl.Samples.Length)
return -1;
startPosition = pos;
bool foundStart = false;
if (scl.Samples[pos] != 1) //SDA is low, it cannot be a start
{
while (pos < scl.Samples.Length && scl.Samples[pos] == 1)
pos++;
if (pos >= scl.Samples.Length)
return -1;
}
else
{
while (pos < scl.Samples.Length && scl.Samples[pos] == 1)
{
if (sda.Samples[pos] != 1)
{
foundStart = true;
break;
}
pos++;
}
}
if (foundStart)
{
endPosition = pos - 1;
return pos;
}
}
return -1;
}
private int ReadByte(int pos, ProtocolAnalyzerSelectedChannel scl, ProtocolAnalyzerSelectedChannel sda, out int byteStart, out int byteEnd, out byte value, out bool ack, out bool frameError)
{
byteStart = 0; byteEnd = 0; value = 0; ack = false; frameError= false;
while (pos < scl.Samples.Length && scl.Samples[pos] == 1) //Find next low clock
pos++;
if (pos >= scl.Samples.Length) //
return -1;
byteStart = pos;
for (int buc = 0; buc < 9; buc++)
{
while (pos < scl.Samples.Length && scl.Samples[pos] == 1) //Find next low clock
pos++;
while (pos < scl.Samples.Length && scl.Samples[pos] == 0) //Find high clock
pos++;
if (pos >= scl.Samples.Length) //
return -1;
byte sampleValue = sda.Samples[pos];
if (buc < 8)
{
value |= (byte)(sampleValue << (7 - buc)); //Get the value
}
else
ack = sampleValue == 0; //Get the ACK/NACK
//Check for frame errors, any change of SDA while SCL is high and is in the middle
//of a byte is a frame error, SDA can change only while the bus is idle or at the end of a byte
//indicating a start or a stop
while (pos < scl.Samples.Length && scl.Samples[pos] == 1)
{
if (sda.Samples[pos] != sampleValue)
frameError = true;
pos++;
}
}
byteEnd = pos - 1;
return pos;
}
public override bool ValidateSettings(ProtocolAnalyzerSettingValue[] SelectedSettings, ProtocolAnalyzerSelectedChannel[] SelectedChannels)
{
if (SelectedChannels == null || SelectedChannels.Length != 2)
return false;
return true;
}
}
}