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Linux Simple I/O Library

libsimpleio is an attempt to encapsulate (as much as possible) the ugliness of Linux I/O device access. It provides services for the following types of I/O devices:

Although libsimpleio was originally intended for Linux microcomputers such as the Raspberry Pi, it can also be useful on larger desktop Linux systems.

The C wrapper functions exported by libsimpleio all follow the same uniform pattern:

  • All C wrapper functions are proper procedures (void f() in C).
  • All input arguments of primitive types (int, float, etc.) are passed by value.
  • All output arguments of primitive types are passed by reference (int *, float *, etc.).
  • All composite types are passed by reference.
  • int32_t is used wherever possible for int and bool arguments.

All of the C wrapper functions are declared between _BEGIN_STD_C and _END_STD_C for C++. Binding modules are provided for Ada, C#, Java, and Free Pascal. Additional source code libraries are provided for Ada, C++, C#, Java, and Free Pascal that define OOP (Object Oriented Programming) classes for libsimpleio.

Quick Setup Instructions for the Impatient

Instructions for installing libsimpleio are found in UserManual.pdf, on pages 5 and 6.


  • 10 February 2021 -- Added support for GPIO output pins implemented using PWM outputs. This is useful for controlling an ON/OFF device such as an LED or solenoid valve driven by PWM output.

  • 18 March 2021 -- Modified the package building procedure to only install the absolute minimum files for the MuntsOS cross-compiled packages. An issue with dpkg installation script execution order may require you to run the following commands after upgrading to this version of libsimpleio:

    sudo find /usr/local -name '*-tmp' -exec rm {} ";"
    sudo apt install --reinstall munts-libsimpleio

    If you have previously installed the MuntsOS cross-compiled packages, you will also need to run one or more of the following commands:

    sudo apt install --reinstall gcc-aarch64-linux-gnu-muntsos-crosstool-libsimpleio
    sudo apt install --reinstall gcc-arm-linux-gnueabihf-muntsos-beaglebone-crosstool-libsimpleio
    sudo apt install --reinstall gcc-arm-linux-gnueabihf-muntsos-raspberrypi1-crosstool-libsimpleio
    sudo apt install --reinstall gcc-arm-linux-gnueabihf-muntsos-raspberrypi2-crosstool-libsimpleio
  • 25 March 2021 -- Added some rudimentary Python client support for the Remote I/O Protocol for raw HID servers (like this or this), in response to a request from a customer who wants to develop a Python Remote I/O Protocol client program that can run on Windows 10 64-bit. Accomplishing this requires a new Windows shared library libremoteio.dll, which was written in the Ada programming language. It also contains the latest hidapi code. Precompiled library files have been added to win/win64/. A few "proof of concept" Python3 programs are in python/.

  • 29 March 2021 -- The new libremoteio.dll also works with Visual Studio C++ programs. Added some Visual Studio C++ projects for creating Remote I/O Protocol client programs for 64-Bit Windows 10.


The user manual for libsimpleio is available at UserManual.pdf.

The man pages specifying the libsimpleio API are available at libsimpleio.html.

Git Repository

The source code is available at:

Use the following command to clone it:

git clone

Package Repository

Prebuilt packages for Debian Linux are available at:

Make With Ada Projects

Questions or comments to Philip Munts

I am available for custom system development (hardware and software) of products using ARM Linux or other microcomputers.


Linux Simple I/O library




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