With the communication protocol clearly defined in chapters \ref{sec:tinyframe} and \ref{sec:units-overview}, respective \ref{sec:wireless} for the wireless gateway, the implementation of a client software is relatively straightforward.
Two proof-of-concept client libraries have been developed in languages C and Python; the Python library can be accessed from MATLAB scripts thanks to the MATLAB's two-way Python integration \cite{matlabpy}. Controlling GEX from MATLAB may be useful when additional processing is required, e.g. with data from the \gls{ADC}; however, in many cases, an open source alternative native to Python exists that could be used for the same purpose, such as the NumPy and SciPy libraries \cite{numpyscipy}.
With the communication protocol clearly defined in chapters \ref{sec:tinyframe} and \ref{sec:units-overview}, respective \ref{sec:wireless} for the wireless gateway, the implementation of a client software is relatively straightforward. Two proof-of-concept client libraries have been developed, in languages C and Python.
\section{General Library Structure}
@ -26,18 +24,66 @@ The structure of a GEX support library is in all cases similar:
Additional utilities may be defined on top of this basic protocol support for the command API of different GEX units, as described in \ref{sec:units-overview}. Those unit-specific ``drivers'' are available in the provided Python library.
\end{itemize}
\section{C Library}
\section{Python Library}
The full C API available to a user program can be found in the library header files. An example of a simple application built with the API is shown below:
The Python GEX library it implements both serial port and raw USB endpoint access, and includes support classes for each unit type. Its development has been proritized over the C library because of it's potential to integrate with MATLAB, and the general ease-of-use that comes with the Python syntax.
\todo[inline]{add the example}
The library is composed of a \textit{transport}, the core class called \textit{client}, and unit classes. Three transport implementations have been developed; the gateway is accessed by wrapping either of the transports in an instance of \mono{DongleAdapter}.
\section{Python Library}
\begin{itemize}
\item\mono{TrxSerialSync} -- virtual serial port access with polling for a response
\item\mono{TrxSerialThread} -- virtual serial port access with a polling thread and semaphore-based notifications
\item\mono{TrxRawUSB} -- similar to \mono{TrxSerialThread}, but using a raw USB endpoint access
\end{itemize}
The unit classes wrap the command and event \gls{API} described in chapter \ref{sec:units-overview}; all classes and methods are annotated by documentation comments for easy understanding.
An example Python program showing a pattern with the \gls{LED} matrix driver IS31FL3730 is presented below as an illustration of the library usage. A photo of the produced pattern can be seen in figure \ref{fig:pydemo}.
\caption{\label{fig:pydemo}GEX Zero with the Micro Dot pHAT add-on board showing a test pattern}
\end{figure}
\section{MATLAB integration}
The Python library can be accessed from MATLAB scripts thanks to the MATLAB's two-way Python integration \cite{matlabpy}. Controlling GEX from MATLAB may be useful when additional processing is required, e.g. with data from the \gls{ADC}; however, in many cases, an open source alternative native to Python exists that could be used for the same purpose, such as the NumPy and SciPy libraries \cite{numpyscipy}.
\todo[inline]{add a matlab example}
The Python library is more advanced than the C library, as it implements the raw USB access and includes support classes for each unit type.
\section{C Library}
The C library is more simplistic than the Python one; it supports only the serial port transport (\gls{UART} or \gls{CDCACM}) and does not implement asynchronous polling or the unit support drivers. What \textit{is} implement---the transport, a basic protocol handler, and payload building and parsing utilities---is sufficient for most applications, though less convenient than the Python library.
\todo[inline]{describe the API and add an example}
This low level library is intended for applications where the performance of the Python implementation is insufficient, or where an integration with existing C code is required. The full \gls{API} can be found in the library header files. A C version of the example Python script controlling a \gls{LED} matrix driver follows:
