logicanalyzer/Software/LogicAnalyzer/I2CProtocolAnalyzer/I2CAnalyzer.cs

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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
{
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return new ProtocolAnalyzerSignal[]
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{
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;
string addr = "";
string op = "";
string addr_space = "";
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byte value;
bool ack;
bool frameError;
bool foundStartStop;
bool repeatStart = false;
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bool addressByte = true;
bool address10 = false;
bool address10read = false;
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byte firstAddressByte = 0;
int pos = FindStartCondition(0, scl, sda, out startPosition, out endPosition);
if (pos == -1)
// If no start is found no further analysis
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return new ProtocolAnalyzedChannel[0];
segments.Add(new ProtocolAnalyzerDataSegment { FirstSample = startPosition, LastSample = endPosition, Value = $"START" });
while (pos < sda.Samples.Length)
{
// iterate through samples byte by byte
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pos = ReadByte(pos, scl, sda, out startPosition, out endPosition, out value, out ack, out frameError);
// no (more) bytes stop processing
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if (pos == -1)
break;
// Create New Empty Segment
var segment = new ProtocolAnalyzerDataSegment { FirstSample = startPosition, LastSample = endPosition, Value = "" };
// convert byte value to printable ascii or '.'
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string asciival = value >= 0x20 && value <= 0x7e ? Encoding.ASCII.GetString(new byte[] { (byte)value }) : "·";
if (address10read)
{
address10read = false;
// Check for 10 bit high address pattern
// 0b11110NNN
if ((value & 0xf8) == 0xf0)
{
// current byte is firstAddressByte with read set
if ((firstAddressByte | 1) == value)
{
// Reset addressByte from repeat start
addressByte = false;
segment.Value += "10b Op Change";
segment.Value += $"\r\nAddress: {addr}";
segment.Value += $" Op: {op}";
// Don't change op until after adding current segment value
op = "Read";
}
// else This is a new start with a new address
}
}
// Check/Parse address byte(s)
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if (addressByte)
{
addressByte = false;
op = (value & 1) == 1 ? "Read" : "Write";
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// Check 10bit High Byte address mask
// 0x11110NNN
if ((value & 0xf8) == 0xf0)
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{
// Mark for 10 bit second byte address parsing
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address10 = true;
firstAddressByte = value;
segment.Value += "10b High Addr Byte";
addr_space = "10b";
addr = $">= {((value & 6) >> 1) << 7}";
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}
else
{
addr = $"0x{value >> 1:X2}";
addr_space = "7b";
// Add 7Bit Address to Segment
// Address (7b): 0x12
segment.Value += $"{addr_space} Address: {addr}";
}
// Add Operation to segment for address Byte
segment.Value += $"\r\nOp: {op}";
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}
// Parse 10 bit low address byte
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else if (address10)
{
address10 = false;
addr = $"0x{((firstAddressByte & 6) << 7) | value:X4}";
// Add 10 bit address to segment using high byte address bits and current byte value
// Address (10b): 0x031A
segment.Value += "10b Low Addr Byte";
segment.Value += $"\r\nAddress: {addr} Op: {op}";
// enable check for high address byte repeat with read bit
address10read = true;
}
if (segment.Value == "")
{
// Add Addr Data to Empty Segment
segment.Value += $"{addr_space} {addr}";
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}
// Add Byte Data to Segment
// HEX_VALUE 'ASCII_VALUE' <A(CK)/N(ACK)/F(rame Error)>
// 0x3A ':' <A>
segment.Value += $"\r\n{op}: 0x{value.ToString("X2")} '{asciival}' <{(ack ? "A" : "N")}{(frameError ? "F" : "")}>";
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// Add segment for processed byte
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segments.Add(segment);
bool isStart;
// Search for next start
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pos = FindStartStopCondition(pos, scl, sda, out isStart, out startPosition, out endPosition, out foundStartStop);
// no more start/stop processing complete
// TODO: REMOVE? this assumes capture ends with whole transaction?
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if (pos == -1)
break;
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if (foundStartStop)
{
string start_stop = (repeatStart && isStart) ? "RE-START" : (isStart ? "START" : "STOP");
// Add START/STOP segment
segments.Add(new ProtocolAnalyzerDataSegment { FirstSample = startPosition, LastSample = endPosition, Value = start_stop });
repeatStart = isStart;
addressByte = true;
}
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// If last start/stop is not start look for following start
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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" });
}
}
ProtocolAnalyzedChannel channel = new ProtocolAnalyzedChannel("SDA", sda.ChannelIndex, renderer, segments.ToArray(), Colors.White, Color.FromUInt32(0x7f008b8b));
return new ProtocolAnalyzedChannel[] { channel
};
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}
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)
{
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byteStart = 0; byteEnd = 0; value = 0; ack = false; frameError = false;
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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;
}
}
}