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Releases: Pi4J/pi4j-v2

PWM and I2C Improvements

29 Apr 13:27
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Thanks to contributions by @fusetim, @taartspi, @eitch, @fdelporte.

Make sure to also read the interviews with Robert von Burg and Tom Aarts.

All changes: 2.5.1...2.6.0

Correct native code for GpioD

21 Mar 09:02
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Sorry! Because of a configuration error, the wrong native code is included in 2.5.0 for the new GpioD Provider. But thanks to the lightning fast action of Robert von Burg we have a fixed version for you to enjoy :-)`

For all other info about the changes in 2.5, see the release notes of 2.5.0.

A lot of changes and... support for Raspberry Pi 5!

18 Mar 13:19
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With over 100 commits from multiple branches, this is a major release with many improvements! With many thanks to the core team (Robert von Burg, Tom Aarts), and a major addition of Alexander Liggesmeyer, Pi4J is again lifted to a higher level!

Warning, the new GpioD Provider needs the latest Raspberry Pi OS version (Debian GNU/Linux 12 (bookworm))

Changes in 2.5.0

  • A new GpioD Provider adds support for the Raspberry Pi 5.
    • Issues #321, #320, #317
    • This new GpioD provider interfaces directly with the Raspberry Pi's gpiochip device, located at /dev/gpiochip.... It leverages the native libgpiod library, which is developed as a part of the Linux kernel. Libgpiod is currently the recommended way to control GPIO pins. Therefore, using this provider is also recommended.
    • This new provider can be used without the need to start a Pi4J application with sudo, so also fixes #212 when you only need DigitalInput and/or DigitalOutput.
  • Better handling of mock Plugins: Plugins can now define if they are mocks, and these are not auto-detected anymore. The default target for the Pi4J library is the Raspberry Pi, and thus auto-detecting mocks on the Pi, which are only for tests is counterintuitive.
  • Extended Providers with a priority: this priority helps to determine which Provider should be loaded, when multiple Providers with the same IOType are being loaded by different plugins. This change enforces that a given IOType can only have one Provider loaded at runtime preventing errors when, for instance, two I2C providers are loaded at the same time, concurrently writing to the I2C bus.
  • Fix for: LinuxFile reused scratch buffers ensuring size was usable. But the limit value cannot be modified so later usage failed as an intended overwrite. Pull request #331, commit ed208f2.
  • Fix for: I2C interface should use a restart between the write and read operation. Pull request #333.
  • Fix for: Shutting down pool executor too early. Commit 7909a2d.
  • ProviderProxyHandler got removed, simplifying provider loading, thus no more reflection on the instances.
  • You can now add and remove IO instances at runtime.
  • You can now easily switch a GPIO from output to an input and vice versa, see issue #26, extending on the work by @MEBoo, in pull request #1.
  • A race condition got fixed in the default runtime registry.
  • Proper life cycle management got added for of all threads in Pi4J.

All changes: 2.4.0...2.5.0

Known Issue

  • Remote I/O error java.base/ Method). Using linuxfs-i2c, dependent upon i2c operations this exception can occur: If the program initially uses read or write, and later uses readRegister or writeRegister there is no exception. However, if the program initially uses readRegister or writeRegister subsequent write or read may encounter this exception. For more info and the temporary fix, check #335.


24 Oct 07:45
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  • Extended LinuxFS plugin
    • PWM provider
    • First set of implementations for Digital Input and Output
    • To be further extended, see #307
  • Don't re-initialize pigpio twice, thus use singleton
  • Implement blink method in DigitalOutputBase
  • Added testcases for I2CRegisterDataReader, I2CRegisterDataWrite
  • Fix I2C write register: multi byte register may fail with large data
  • Fix mock SPI.transfer() functionality
  • Add readEntireMockBuffer() method to class MockSpi
  • Fix for data read over I2C becomes out of sync over a slower wireless network
  • Use Socket#setSoTimeout to timeout read requests of GPIO socket implementation

Thanks to @GeVanCo, @MMMMMNG, @IAmNickNack, @savageautomate, @eitch, @taartspi, @FDelporte


2.3.0 - SPI and PiGPIO Improvements

06 Feb 12:59
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  • Improvements for PIGPIO.gpioCfgInterfaces by @bwaldvogel
  • New i2c interface to support multibyte register address by @taartspi
  • Fix in LinuxFsI2C byte array offset by @harlanhu
  • Remove unused JNA references by @taartspi


2.2.1 - SPI improvements

17 Oct 07:43
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Multiple fixes by @taartspi

  • Better error message when mixing 32- and 64-bit artifacts
  • SPI improvements:
    • Add missing initialization in constructor
    • Track weather the user set the mode or bus config values to improve the use of SPI flags



29 Aug 08:52
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Thanks to all contributors, multiple improvements were added:

  • by @taartspi to improve SPI initialization, see #229
  • by @haumacher regarding the use of ByteBuffers, see #185
  • by @savageautomate regarding the polarity of digital output, see #93
  • by @gugrim to ensure positive values are returned from reading unless at end of file, see #164
  • by @eitch to also export LinuxFS I2C in
  • by @eitch to also copy native libs to distribution zip
  • by @hagen to be able to configure sample rate and peripheral in PiGpio
  • by Saskia Bikle to add an implementation of deregistration/shutdown for IO's
  • by @savageautomate to add a new value "flags" too SPI implementation



10 Dec 15:40
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[Fix] Also export linuxfs i2c in makes it possible to add the LinuxFsPlugin provider when not loading using autocontext


26 Oct 12:29
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  • Build improvements
  • #141: Sort Interfaces When Creating Proxies

The first release of the totally renewed Pi4J V2

26 Aug 08:50
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Yoohoo it's here! After a lot of work we present you the totally renewed Pi4J library!

For the full documentation, please check

Most important info on V2:

  • Java 11 and up
  • Breaking change with V1 as the framework has been completely rearchitected (see
  • No longer include support for peripheral devices and add-on chipsets/boards as part of the core project
  • Easier to extend, maintain and test
  • Uses PiGpio as the native library (WiringPi which was used in V1 got deprecated in 2019)
  • Builds as modules to fully support future evolutions in Java
  • Uses minimal dependencies (only SLF4J)
  • Different examples how to get started (also with JavaFX) are available on
  • And more as described on