From dff49e1f7c0f414e1fb66fa4373f5c3c2ca9fa67 Mon Sep 17 00:00:00 2001
From: "copilot-swe-agent[bot]" <198982749+Copilot@users.noreply.github.com>
Date: Tue, 2 Jun 2026 15:54:53 +0000
Subject: [PATCH 1/5] Initial plan


From 17ad125fab3cae09e330bdff7497bcce35fc1a76 Mon Sep 17 00:00:00 2001
From: "copilot-swe-agent[bot]" <198982749+Copilot@users.noreply.github.com>
Date: Tue, 2 Jun 2026 15:57:54 +0000
Subject: [PATCH 2/5] Allow configuring FT4222 I2C master clock frequency

---
 src/devices/Ft4222/Ft4222Device.cs |  8 +++++++-
 src/devices/Ft4222/Ft4222I2cBus.cs | 31 ++++++++++++++++++++++++++++--
 src/devices/Ft4222/README.md       |  8 ++++++++
 3 files changed, 44 insertions(+), 3 deletions(-)

diff --git a/src/devices/Ft4222/Ft4222Device.cs b/src/devices/Ft4222/Ft4222Device.cs
index 8bd325f20a..f501332afd 100644
--- a/src/devices/Ft4222/Ft4222Device.cs
+++ b/src/devices/Ft4222/Ft4222Device.cs
@@ -16,6 +16,12 @@ namespace Iot.Device.Ft4222
     /// </summary>
     public class Ft4222Device : FtDevice
     {
+        /// <summary>
+        /// Gets or sets the I2C master clock frequency in kbps used when creating an I2C bus.
+        /// Supported range is 60 to 3400 kbps. Defaults to 400 kbps.
+        /// </summary>
+        public uint I2cBusFrequencyKbps { get; set; } = Ft4222I2cBus.DefaultI2cMasterFrequencyKbps;
+
         /// <summary>
         /// Gets all the FT4222 connected
         /// </summary>
@@ -69,7 +75,7 @@ protected override I2cBusManager CreateI2cBusCore(int busNumber, int[]? pins)
                 throw new ArgumentOutOfRangeException(nameof(busNumber));
             }
 
-            return new I2cBusManager(this, busNumber, pins, new Ft4222I2cBus(this));
+            return new I2cBusManager(this, busNumber, pins, new Ft4222I2cBus(this, I2cBusFrequencyKbps));
         }
 
         /// <inheritdoc />
diff --git a/src/devices/Ft4222/Ft4222I2cBus.cs b/src/devices/Ft4222/Ft4222I2cBus.cs
index 31e3682fd8..eb9504bce4 100644
--- a/src/devices/Ft4222/Ft4222I2cBus.cs
+++ b/src/devices/Ft4222/Ft4222I2cBus.cs
@@ -18,11 +18,29 @@ namespace Iot.Device.Ft4222
     /// </summary>
     internal class Ft4222I2cBus : I2cBus
     {
-        private const uint I2cMasterFrequencyKbps = 400;
+        /// <summary>
+        /// The default I2C master clock frequency in kbps used when none is specified.
+        /// </summary>
+        public const uint DefaultI2cMasterFrequencyKbps = 400;
+
+        /// <summary>
+        /// The minimum I2C master clock frequency in kbps supported by the FT4222.
+        /// </summary>
+        public const uint MinimumI2cMasterFrequencyKbps = 60;
+
+        /// <summary>
+        /// The maximum I2C master clock frequency in kbps supported by the FT4222.
+        /// </summary>
+        public const uint MaximumI2cMasterFrequencyKbps = 3400;
 
         private readonly Dictionary<int, I2cDevice> _usedAddresses = new Dictionary<int, I2cDevice>();
         private SafeFtHandle _ftHandle;
 
+        /// <summary>
+        /// Gets the I2C master clock frequency in kbps used by this bus.
+        /// </summary>
+        public uint I2cMasterFrequencyKbps { get; }
+
         /// <summary>
         /// Store the FTDI Device Information
         /// </summary>
@@ -32,8 +50,16 @@ internal class Ft4222I2cBus : I2cBus
         /// Create a FT4222 I2C Device
         /// </summary>
         /// <param name="deviceInformation">Device information. Use FtCommon.GetDevices to get it.</param>
-        public Ft4222I2cBus(Ft4222Device deviceInformation)
+        /// <param name="i2cMasterFrequencyKbps">The I2C master clock frequency in kbps. Supported range is 60 to 3400 kbps.</param>
+        public Ft4222I2cBus(Ft4222Device deviceInformation, uint i2cMasterFrequencyKbps = DefaultI2cMasterFrequencyKbps)
         {
+            if (i2cMasterFrequencyKbps < MinimumI2cMasterFrequencyKbps || i2cMasterFrequencyKbps > MaximumI2cMasterFrequencyKbps)
+            {
+                throw new ArgumentOutOfRangeException(nameof(i2cMasterFrequencyKbps), $"I2C master clock frequency must be between {MinimumI2cMasterFrequencyKbps} and {MaximumI2cMasterFrequencyKbps} kbps.");
+            }
+
+            I2cMasterFrequencyKbps = i2cMasterFrequencyKbps;
+
             switch (deviceInformation.Type)
             {
                 case FtDeviceType.Ft4222HMode0or2With2Interfaces:
@@ -68,6 +94,7 @@ public Ft4222I2cBus(Ft4222Device deviceInformation)
                 throw new IOException($"Failed to initialize I2C Master mode on device: {DeviceInformation.Description}, status: {ftStatus}");
             }
         }
+        }
 
         internal void Read(int deviceAddress, Span<byte> buffer)
         {
diff --git a/src/devices/Ft4222/README.md b/src/devices/Ft4222/README.md
index 0f1a76ba49..c1c6e9574d 100644
--- a/src/devices/Ft4222/README.md
+++ b/src/devices/Ft4222/README.md
@@ -94,6 +94,14 @@ if (bme280.TryReadTemperature(out Temperature temperature))
 }
 ```
 
+By default, the I2C bus is initialized at 400 kbps. You can change the I2C master clock frequency (supported range is 60 to 3400 kbps) by setting `I2cBusFrequencyKbps` on the `Ft4222Device` before creating the bus:
+
+```csharp
+Ft4222Device device = new Ft4222Device(FtCommon.GetDevices()[0]);
+device.I2cBusFrequencyKbps = 100;
+using I2cBus ftI2c = device.CreateI2cBus();
+```
+
 ### SPI
 
 ```Ft4222Spi``` is the SPI driver which you can pass later to any device requiring SPI or directly use it to send SPI commands. The SPI implementation is fully compatible with ```System.Device.Spi.SpiDevice```.

From 68b667661aa855702c36d197b7d8a09bb8305fbc Mon Sep 17 00:00:00 2001
From: "copilot-swe-agent[bot]" <198982749+Copilot@users.noreply.github.com>
Date: Tue, 2 Jun 2026 16:38:51 +0000
Subject: [PATCH 3/5] Fix stray closing brace breaking compilation in
 Ft4222I2cBus

---
 src/devices/Ft4222/Ft4222I2cBus.cs | 1 -
 1 file changed, 1 deletion(-)

diff --git a/src/devices/Ft4222/Ft4222I2cBus.cs b/src/devices/Ft4222/Ft4222I2cBus.cs
index eb9504bce4..39210312a0 100644
--- a/src/devices/Ft4222/Ft4222I2cBus.cs
+++ b/src/devices/Ft4222/Ft4222I2cBus.cs
@@ -94,7 +94,6 @@ public Ft4222I2cBus(Ft4222Device deviceInformation, uint i2cMasterFrequencyKbps
                 throw new IOException($"Failed to initialize I2C Master mode on device: {DeviceInformation.Description}, status: {ftStatus}");
             }
         }
-        }
 
         internal void Read(int deviceAddress, Span<byte> buffer)
         {

From e93fbe7e54096c52c6ee5e2e38208879f1c1e477 Mon Sep 17 00:00:00 2001
From: "copilot-swe-agent[bot]" <198982749+Copilot@users.noreply.github.com>
Date: Sat, 6 Jun 2026 15:34:33 +0000
Subject: [PATCH 4/5] Adjust Ft4222I2cBus API for review feedback

---
 src/devices/Ft4222/Ft4222I2cBus.cs | 13 +++++++++++--
 1 file changed, 11 insertions(+), 2 deletions(-)

diff --git a/src/devices/Ft4222/Ft4222I2cBus.cs b/src/devices/Ft4222/Ft4222I2cBus.cs
index 39210312a0..c56ddcd4bd 100644
--- a/src/devices/Ft4222/Ft4222I2cBus.cs
+++ b/src/devices/Ft4222/Ft4222I2cBus.cs
@@ -16,7 +16,7 @@ namespace Iot.Device.Ft4222
     /// <summary>
     /// FT4222 I2C Device
     /// </summary>
-    internal class Ft4222I2cBus : I2cBus
+    public class Ft4222I2cBus : I2cBus
     {
         /// <summary>
         /// The default I2C master clock frequency in kbps used when none is specified.
@@ -46,12 +46,21 @@ internal class Ft4222I2cBus : I2cBus
         /// </summary>
         public Ft4222Device DeviceInformation { get; private set; }
 
+        /// <summary>
+        /// Create a FT4222 I2C Device
+        /// </summary>
+        /// <param name="deviceInformation">Device information. Use FtCommon.GetDevices to get it.</param>
+        public Ft4222I2cBus(Ft4222Device deviceInformation)
+            : this(deviceInformation, DefaultI2cMasterFrequencyKbps)
+        {
+        }
+
         /// <summary>
         /// Create a FT4222 I2C Device
         /// </summary>
         /// <param name="deviceInformation">Device information. Use FtCommon.GetDevices to get it.</param>
         /// <param name="i2cMasterFrequencyKbps">The I2C master clock frequency in kbps. Supported range is 60 to 3400 kbps.</param>
-        public Ft4222I2cBus(Ft4222Device deviceInformation, uint i2cMasterFrequencyKbps = DefaultI2cMasterFrequencyKbps)
+        public Ft4222I2cBus(Ft4222Device deviceInformation, uint i2cMasterFrequencyKbps)
         {
             if (i2cMasterFrequencyKbps < MinimumI2cMasterFrequencyKbps || i2cMasterFrequencyKbps > MaximumI2cMasterFrequencyKbps)
             {

From 84a18065cf3649b404cf290134e905136b0e51d8 Mon Sep 17 00:00:00 2001
From: "copilot-swe-agent[bot]" <198982749+Copilot@users.noreply.github.com>
Date: Sat, 6 Jun 2026 15:37:59 +0000
Subject: [PATCH 5/5] Clarify Ft4222I2cBus constructor docs

---
 src/devices/Ft4222/Ft4222I2cBus.cs | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/devices/Ft4222/Ft4222I2cBus.cs b/src/devices/Ft4222/Ft4222I2cBus.cs
index c56ddcd4bd..ebd3063a62 100644
--- a/src/devices/Ft4222/Ft4222I2cBus.cs
+++ b/src/devices/Ft4222/Ft4222I2cBus.cs
@@ -47,7 +47,7 @@ public class Ft4222I2cBus : I2cBus
         public Ft4222Device DeviceInformation { get; private set; }
 
         /// <summary>
-        /// Create a FT4222 I2C Device
+        /// Create a FT4222 I2C device using the default I2C master clock frequency.
         /// </summary>
         /// <param name="deviceInformation">Device information. Use FtCommon.GetDevices to get it.</param>
         public Ft4222I2cBus(Ft4222Device deviceInformation)
@@ -56,7 +56,7 @@ public Ft4222I2cBus(Ft4222Device deviceInformation)
         }
 
         /// <summary>
-        /// Create a FT4222 I2C Device
+        /// Create a FT4222 I2C device using the specified I2C master clock frequency.
         /// </summary>
         /// <param name="deviceInformation">Device information. Use FtCommon.GetDevices to get it.</param>
         /// <param name="i2cMasterFrequencyKbps">The I2C master clock frequency in kbps. Supported range is 60 to 3400 kbps.</param>