Sc16is7x2 code quality

Source/Meadow.Foundation.Peripherals/ICs.ADC.Ads1x15/Driver/Ads1x15Base.Enums.cs

@@ -35,27 +35,27 @@ public enum Addresses : byte
         public enum FsrGain
         {
             /// <summary>
-            /// 2/3rds
+            /// Gain = 2/3rds. Range: ±6.144 V
             /// </summary>
             TwoThirds = 0x00,
             /// <summary>
-            /// 1
+            /// Gain = 1. Range: ±4.096 V
             /// </summary>
             One = 0x01,
             /// <summary>
-            /// 2
+            /// Gain = 2. Range: ±2.048 V
             /// </summary>
             Two = 0x02,
             /// <summary>
-            /// 4
+            /// Gain = 4. Range: ±1.024 V
             /// </summary>
             Four = 0x03,
             /// <summary>
-            /// 8
+            /// Gain = 8. Range: ±0.512 V
             /// </summary>
             Eight = 0x04,
             /// <summary>
-            /// 16
+            /// Gain = 16. Range: ±0.256 V
             /// </summary>
             Sixteen = 0x05
         }

Source/Meadow.Foundation.Peripherals/ICs.IOExpanders.Sc16is7x2/Driver/FifoBuffer.cs

@@ -1,12 +1,17 @@
 using System;
 using System.Text;
+using System.Threading;
 
 namespace Meadow.Foundation.ICs.IOExpanders;
 
 /// <summary>
 /// This FIFO buffer is implemented as a circular buffer. (Standard computer science stuff)
 /// It operates on bytes. The only special method is WriteString,
 /// which writes a string to the buffer after converting it with Encoding.ASCII.GetBytes().
+///
+/// 2024.04.20, KW: I've recently discovered the CircularBuffer class in the Meadow.Contracts library.
+///                 We should perhaps use that instead of this custom implementation.
+///                 But this method is specific to bytes, so it might still be more efficient.
 /// </summary>
 public class FifoBuffer
 {
@@ -39,8 +44,8 @@ public FifoBuffer(int capacity)
             throw new ArgumentException("Capacity must be greater than 0.", nameof(capacity));
 
         _buffer = new byte[capacity];
-        _nextRead = 0;  // The next read position.
-        _nextWrite = 0; // The next write position.
+        _nextRead = 0;  // The next read position.  (Tail)
+        _nextWrite = 0; // The next write position. (Head)
         _count = 0;     // The number of items in the buffer.
     }
 
@@ -54,6 +59,8 @@ public void Clear()
         _count = 0;     // The number of items in the buffer.
     }
 
+    private int skippedBytes = 0;
+    private DateTime skippedBytesLastLogged = DateTime.MinValue;
     /// <summary>
     /// Add new item to the _nestWrite position in the buffer.
     /// Then move the _nextWrite position. If it goes beyond the capacity, it will wrap around to 0.
@@ -64,7 +71,18 @@ public void Clear()
     public void Write(byte item)
     {
         if (_count == Capacity)
-            throw new InvalidOperationException("The buffer is full.");
+        {
+            //throw new InvalidOperationException($"The software FIFO buffer is full. Capacity is {Capacity} bytes.");
+            // 21.04.2024, KW: These exception must be handled by the caller. We count the occurences and throw an error every 5 seconds.
+            skippedBytes++;
+            if (DateTime.Now - skippedBytesLastLogged > TimeSpan.FromSeconds(5))
+            {
+                skippedBytesLastLogged = DateTime.Now;
+                //Resolver.Log.Info($"The software FIFO buffer is full. Capacity is {Capacity} bytes. Skipped bytes: {skippedBytes} (This message will be repeated every 5 seconds)");
+                throw new Exception($"The software FIFO buffer is full. Capacity is {Capacity} bytes. Skipped bytes: {skippedBytes} (This message will be repeated every 5 seconds)");
+            }
+            return;
+        }
 
         _buffer[_nextWrite] = item;
         _nextWrite = (_nextWrite + 1) % Capacity;   // Move _nextWrite forward and possibly wrap.
@@ -134,4 +152,53 @@ public void WriteString(string text)
             Write((byte)c);
         }
     }
+
+    /// <summary>
+    /// Copied from the CircularBuffer class in the Meadow.Contracts library.
+    /// Removes items from the buffer and places them in a target array
+    /// </summary>
+    /// <param name="destination">The destination array for the move</param>
+    /// <param name="index">The beginning index of the destination</param>
+    /// <param name="count">The desired number of items to move</param>
+    /// <returns>The actual number of items moved</returns>
+    public int MoveItemsTo(byte[] destination, int index, int count)
+    {
+        if (count <= 0) { return 0; }
+
+        // How many are we moving?
+        // Move from current toward the tail
+        var actual = (count > Count) ? Count : count;
+        var fromReadToEnd = _buffer.Length - _nextRead;
+
+        //Resolver.Log.Info($"MoveItemsTo() _nextRead={_nextRead} _nextWrite={_nextWrite} actual={actual} fromReadToEnd={fromReadToEnd}");
+
+        if ((_nextRead < _nextWrite)
+            || (_nextRead == 0 && _count == Capacity)
+            || (fromReadToEnd >= actual))
+        {
+            // the data is linear, just copy
+            Array.Copy(_buffer, _nextRead, destination, index, actual);
+
+            // move the tail pointer
+            _nextRead += actual;
+            _count -= actual;
+        }
+        else
+        {
+            // there's a data wrap
+            // copy from here to the end
+            Array.Copy(_buffer, _nextRead, destination, index, fromReadToEnd);
+            // now copy from the start (tail == 0) the remaining data
+            _nextRead = 0;
+            _count -= fromReadToEnd;
+            var remaining = actual - fromReadToEnd;
+            Array.Copy(_buffer, _nextRead, destination, index + fromReadToEnd, remaining);
+
+            // move the tail pointer
+            _nextRead = remaining;
+            _count -= remaining;
+        }
+
+        return actual;
+    }
 }

Source/Meadow.Foundation.Peripherals/ICs.IOExpanders.Sc16is7x2/Driver/Sc16is7x2.Enums.cs

@@ -75,6 +75,75 @@ public enum Addresses : byte
             /// The default bus address (0x48)
             /// </summary>
             Default = Address_0x48,
+
+            // A new set of constants that show the direct relationship between the address pins and the I2C address
+            // Please refer to the datasheet for the SC16IS752/SC16IS762 page 39.
+            // Note that the address in the datasheet multiplied by 2, because they include a left shit for the R/W bit.
+
+            /// <summary>
+            /// A1 pin connected to Vdd, A0 pin connected to Vdd
+            /// </summary>
+            A1Vdd_A0Vdd = 0x48,
+            /// <summary>
+            /// A1 pin connected to Vdd, A0 pin connected to Gnd
+            /// </summary>
+            A1Vdd_A0Gnd = 0x49,
+            /// <summary>
+            /// A1 pin connected to Vdd, A0 pin connected to SCL
+            /// </summary>
+            A1Vdd_A0Scl = 0x4A,
+            /// <summary>
+            /// A1 pin connected to Vdd, A0 pin connected to SDA
+            /// </summary>
+            A1Vdd_A0Sda = 0x4B,
+            /// <summary>
+            /// A1 pin connected to Gnd, A0 pin connected to Vdd
+            /// </summary>
+            A1Gnd_A0Vdd = 0x4C,
+            /// <summary>
+            /// A1 pin connected to Gnd, A0 pin connected to Gnd
+            /// </summary>
+            A1Gnd_A0Gnd = 0x4D,
+            /// <summary>
+            /// A1 pin connected to Gnd, A0 pin connected to SCL
+            /// </summary>
+            A1Gnd_A0Scl = 0x4E,
+            /// <summary>
+            /// A1 pin connected to Gnd, A0 pin connected to SDA
+            /// </summary>
+            A1Gnd_A0Sda = 0x4F,
+            /// <summary>
+            /// A1 pin connected to SCL, A0 pin connected to Vdd
+            /// </summary>
+            A1Scl_A0Vdd = 0x50,
+            /// <summary>
+            /// A1 pin connected to SCL, A0 pin connected to Gnd
+            /// </summary>
+            A1Scl_A0Gnd = 0x51,
+            /// <summary>
+            /// A1 pin connected to SCL, A0 pin connected to SCL
+            /// </summary>
+            A1Scl_A0Scl = 0x52,
+            /// <summary>
+            /// A1 pin connected to SCL, A0 pin connected to SDA
+            /// </summary>
+            A1Scl_A0Sda = 0x53,
+            /// <summary>
+            /// A1 pin connected to SDA, A0 pin connected to Vdd
+            /// </summary>
+            A1Sda_A0Vdd = 0x54,
+            /// <summary>
+            /// A1 pin connected to SDA, A0 pin connected to Gnd
+            /// </summary>
+            A1Sda_A0Gnd = 0x55,
+            /// <summary>
+            /// A1 pin connected to SDA, A0 pin connected to SCL
+            /// </summary>
+            A1Sda_A0Scl = 0x56,
+            /// <summary>
+            /// A1 pin connected to SDA, A0 pin connected to SDA
+            /// </summary>
+            A1Sda_A0Sda = 0x57,
         }
 
         internal enum Registers : byte

Source/Meadow.Foundation.Peripherals/ICs.IOExpanders.Sc16is7x2/Driver/Sc16is7x2.I2c.cs

@@ -29,6 +29,7 @@ public Sc16is7x2(II2cBus i2cBus, Frequency oscillatorFrequency, Addresses addres
             : this(oscillatorFrequency, irq, latchGpioInterrupt)
         {
             _i2cComms = new I2cCommunications(i2cBus, (byte)address);
+            Reset();    // We need to call this _after_ the I2C communications object is created
         }
     }
 }