RPICSIO - A C# I/O Library for the Raspberry Pi

Summary

RPICSIO is a free and open source .NET v4 library which provides a comprehensive C# input/output solution for the Raspberry Pi 2 Mono environment. Using RPICSIO, you can easily read and write to the GPIO pins (and trigger interrupt events from state changes) and launch and control SPI, I2C, PWM and UART devices. RPICSIO is intended to be a comprehensive solution for I/O on the Raspberry Pi 2. At the current time, RPICSIO has only been tested on the Raspberry Pi 2. Most things will probably work on the Raspberry Pi 3 - but it has not been verified and the functionality on the Raspberry Pi 0 is unknown. A list of the known outstanding issues can be found on the Known Bugs And ToDo List page. Besides the downloadable DLL library and source code the RPICSIO contains complete Help Files and Examples.

Note: In order to use the RPICSIO library, C# and Mono must be installed on the Raspberry Pi.

 

Example RPICSIO Code which Toggles a GPIO Pin at 1Hz

Capabilities

• Provides simple and transparent read/write access (including the triggering of events) to the GPIO pins of a Raspberry Pi 2. A maximum output frequency of about 2.4MHz is possible when using a memory mapped port class and about 1.1Khz when using the SYSFS class.
• The SPI port is fully supported. It is possible to use GPIO ports to provide a large number of SPI device select lines.
• The I2C port is fully supported.
• The Serial/UART port is fully supported.
• The Pulse Width Modulation (PWM) device is fully supported. The PWM duty cycle can be specified in nano-seconds or as a percentage of the base frequency.
• Developed on Raspbian Linux v4.4.32 freely available for the Raspberry Pi.
• Tested with the Mono JIT compiler v3.2.8 but is probably also compatible with other versions.
• The software is written in C# and a .NET project is included with the source code.

What RPICSIO Does Not Do

• The Raspbian Linux running on the Raspberry Pi is not a real-time operating system. This means, for example, although you might set a port to output a 100Khz square wave the actual timing of some of the pulses may vary (and there may be gaps) as the process is pre-emptively swapped in and out by the kernel.
• The SPI, I2C, PWM and UART devices are supported on the Raspberry Pi 2 as of version 01.00 but the RPICSIO software has not been tested on the Raspberry Pi 3 or the Raspberry Pi 0. There are no plans, at this time, to provide support for the original Raspberry Pi.
• The RPICSIO Library cannot do much in the way of I/O unless the process it is running in has root privileges. This is enforced by the Linux O/S and means that any code which incorporates the RPICSIO Library must run as root.
• The RPICSIO Library will adjust the GPIO's in order to set them as input or output (and to set the pull-up or pull down resistors). The other devices such as PI, I2C, PWM and UART must be specifically enabled in order for them to function. This must be done from by the user using a tool such as raspi-config. In addition, some of the devices (PWM and UART) require extra actions in order to make them function. See the extensive comments on their example help pages for more information.
• The InterruptPort functionality is a pseudo interrupt. It operates by monitoring the designated GPIOs out of band in a separate, continuously computable, thread. In concept, it is not dissimilar to the C Poll() call.

Help Files and Manual

The Help Pages discuss the usage of the RPICSIO software and calling conventions for the classes it contains. The RPICSIO software zip files (below) also contain these help files.

Sample Code

The RPICSIO help pages contain an Example Code section which illustrates the usage of the RPICSIO library.

Source Code

A web browsable version of the RPICSIO Source Code is available.

Installation

If you download only the RPICSIO.dll (rather than the source) you can use it like any other .NET dll library. Either place the RPICSIO.dll in the same directory as the exe file or copy the dll into the /usr/lib directory where it will be available to all programs that need it. Of course, you will need to reference it in the .NET solution just as you would any other library.

If you download the source code you can include the RPICSIO.proj into your .NET solution in the usual way and the software should compile.

License

The contents of the RPICSIO web pages, the help pages, the downloadable executables and the source code are are provided "as is" without any warranty of any kind and without any claim to being error free or complete. Please be aware that the documentation, executables or source code provided may be out-of-date, incomplete, erroneous or simply unsuitable for your purposes. Any use you make of the RPICSIO documentation, source code and executables is entirely at your discretion and any consequences of that use are entirely your responsibility.

All source code and executable libraries are provided under the terms of the MIT License.

Download

• The version 01.00.01 zipped binaries. (109Kb)
• The RPICSIO source code on GitHub (197Kb)
• A web browsable version of the RPICSIO Source Code is available.
• The Version Change Log.