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Release Notes

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3.0.0.3000 (2026-06-29) Prerelease​

Libraries​

  • Support HTTPS with no CA certificate option

Firmware​

  • No changes. Firmware version 3.0.0.2000 remains the recommended version.

Known issues

  • SC20xxx: Webcam reconnect fails after disconnect when connected through a hub.
  • USB host hubs do not support low-speed (LS) devices. To use a mouse or keyboard, connect it directly to the USB port or use a full-speed device instead.

Visual Studio Extension​

  • Fixed Visual Studio freezing/closing when deploying to a low-memory device
  • Support packages.config and PackageReference
  • Ctrl+F5 now deploys the application and reboots the device immediately. There is no longer a 60-second wait.
  • The same NuGet package can be used on both desktop and device projects, as long as it is compatible with the target device.

Known issues

  • An exclamation mark may still appear due to duplicate NuGet packages when using the PackageReference configuration, but it is harmless and can be safely ignored.
  • Users need to add the GHIElectronics.TinyCLR.Drawing NuGet package when adding a bitmap or image resource (if it has not already been added to the project).
  • Users need to run Run Custom Tool on the resource to (re)generate the GetBytes() / GetBitmap() accessors.
  • Desktop mode does not support Debug.WriteLine; use Console.WriteLine instead.

TinyCLR Config​

  • Build-tca now supports PackageReference

Visual Studio Code extension​

  • Update the fixes from Visual Studio extension.

3.0.0.2000 (2026-06-12) Prerelease​

TinyCLR OS 3.0 is a major release. The headline change is broad runtime and library support for modern C#: generics and generic collections, Task/async, Tuple/ValueTuple, LINQ, ranges and indices, record types, and required members. It also adds native RLP support, USB hub and webcam support, multi-interface non-blocking networking, an updated Visual Studio extension for VS2022/VS2026, and a new Visual Studio Code extension.

Libraries​

New features

  • System.Collections.Generic: List<T>, Dictionary<TKey, TValue>, the generic interfaces (IList<T>, IDictionary<,>, IEnumerable<T>, ICollection<T>, …), and Comparer<T>/EqualityComparer<T>.
  • System.Threading.Tasks: Task, Task<T>, Task.Run, Task.Delay, Task.WhenAll, Task.WhenAny, and async/await support.
  • cooperative cancellation: CancellationToken, CancellationTokenSource, and OperationCanceledException.
  • System.Tuple and System.ValueTuple, including tuple literals and deconstruction.
  • System.Linq (LINQ-to-Objects).
  • System.Index and System.Range, enabling from-end indexing and slicing (for example array[^1] and array[1..3]).
  • the generic delegates Func<>, Predicate<T>, Comparison<T>, and Converter<T>, plus the generic interfaces IEquatable<T> and IComparable<T>.
  • the support types behind modern C#: init-only setters and record types (IsExternalInit), required members, [ModuleInitializer], and [CallerArgumentExpression].
  • Activator.CreateInstance<T>().
  • HashSet<T>.
  • System.Console.
  • System.Device.Gpio, System.Device.I2c, System.Device.Pwm, System.Device.Spi, System.IO.Ports, System.Security.Cryptography, System.Xml
  • desktop/dual-mode companion assemblies (GPIO, SPI, I2C, PWM, UART, ADC, SerialPort, Network, Cryptography, …) for PC-side build and test.
  • USB host webcam support.
  • GpioController.WaitForEvent and StringBuilder.AppendFormat.
  • XML documentation for the TinyCLR APIs — IntelliSense tooltips and summaries now appear in the editor.

Fixes

  • Fixed TimeSpan.FromXxx / TimeSpan.TotalMilliseconds returning negative values.
  • Fixed DateTime subtraction returning a negative elapsed time.
  • Fixed a crash involving double.PositiveInfinity / double.NegativeInfinity.
  • Fixed FTP and HTTP server exceptions, and reworked MQTT.
  • Fixed UI touch-event routing and improved scroll/redraw performance.
  • IsDriveModeSupported no longer requires a pin.
  • Tweak UI.
  • Reworked the cryptography library.
  • Separated the socket send and receive timeouts so that setting one no longer blocks the other.

Firmware​

New features

  • RLP (native runtime-loadable procedures) support.
  • the CLR runtime support behind the new library features: generics and generic collections (List, Dictionary), Tuple/ValueTuple, LINQ, and Task/async, with improved boxing, unboxing, and generic type handling.
  • a native Task controller for background and driver work.
  • C# 11 language support.
  • USB host hub support (cascaded hubs and multiple USB mass-storage sticks) and USB webcam capture (DCMI + DMA).
  • multiple simultaneous network interfaces, non-blocking network bring-up (EnableAsync), non-blocking DNS, socket Shutdown, and TCP listener support.
  • a hardware RNG source for the network security stack.
  • firmware support for reading and setting the RTC (exposed through the TinyCLR-Config CLI).

Fixes & improvements

  • Fixed several floating-point / number-to-string formatting issues (G-format rounding, exponent, precision, and trailing zeros).
  • Fixed CAN: classic (non-FD) operation failed when no data bit-rate is set.
  • Fixed mass-storage (MSC) read/write and mount-after-format.
  • Fixed DigitalSignal capture crashed with at 2.5MHz .
  • Fixed inconsistent comparison of simple value types.
  • Fixed SD card read/write disabling global interrupts (IRQs).
  • Fixed SD card mounting.
  • Reworked networking.
  • Reworked low-power / sleep handling.
  • Reworked EtherNet/IP (board-to-board Class-1 I/O).
  • Improved I2C (Master and Client modes).
  • The deploy error now reports which assembly exceeds the maximum size.

Known issues

  • SC13xxx: System crash when use Dictionary if memory is low.
  • SC20xxx: Webcam reconnect fails after disconnect when connected through a hub.
  • USB host hubs do not support low-speed (LS) devices. To use a mouse or keyboard, connect it directly to the USB port or use a full-speed device instead.

Visual Studio Extension​

New features

  • Dual mode: A TinyCLR project can run in both device and Desktop mode (.NET Framework 4.8).
  • support for connecting to multiple devices / ports.

Fixes

  • Visual Studio no longer deadlocks or blocks when a device flash fails.
  • A "PNG is not supported" error message is displayed when a PNG resource is detected.

Known issues

  • Users need to add the GHIElectronics.TinyCLR.Drawing NuGet package when adding a bitmap or image resource (if it has not already been added to the project).
  • Users need to run Run Custom Tool on the resource to (re)generate the GetBytes() / GetBitmap() accessors.
  • Desktop mode does not support Debug.WriteLine; use Console.WriteLine instead.

TinyCLR Config​

New features

  • a command-line (CLI) mode for scripted/headless device operations.
  • export/generation of .tca configuration archive files.
  • support for connecting to and managing multiple devices.
  • get/set of the real-time clock (RTC) through the CLI.

Fixes & improvements

  • Auto-scales the UI by font and fixed the layout across different screen resolutions.
  • No longer crashes when the selected COM port is already held by another application.

Known issues

  • CLI: reboot need to called twice to reset the device

Visual Studio Code extension​

  • Feature parity with the Visual Studio extension.

2.4.1.1000 (2026-03-25) RTW​

Firmware​

  • Fixed multiple issues in floating-point string formatting (rounding, exponent, precision)

2.4.0.1000 (2026-03-16) RTW​

Firmware​

  • SC20xxx only change
  • Add SDRAM overclock support
  • Fix CPU usage statistics
  • Add WPA/WPA2 support for WiFi in both AP and Client modes

Libraries​

  • HTTPS server now supports TLS 1.2