added the python example and a photo

ch.conclusion.tex

@@ -1,3 +1,3 @@
 \chapter{Conclusion}
 
-bla
+\todo[inline]{xy was developed ... project works great ... possible future improvements ...}

ch.hardware_realization.tex

@@ -1,3 +1,3 @@
 \chapter{Hardware Realization}
 
-\todo{TODO}
+\todo[inline]{TODO schematics (maybe in appendix). photos of the PCBs. Links to this chapter from elsewhere}

ch.pc_software.tex

@@ -1,8 +1,6 @@
 \chapter{Client Software}
 
-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.
+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.
-
-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}.
 
 \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}.
+
+\begin{minted}{python}
+#!/bin/env python3
+import gex  
+with gex.Client(gex.TrxRawUSB()) as client:
+    bus = gex.I2C(client, 'i2c')
+    addr = 0x61
+    bus.write_reg(addr, 0x00, 0b00011000) # dual matrix
+    bus.write_reg(addr, 0x0D, 0b00001110) # 34 mA
+    bus.write_reg(addr, 0x19, 64) # set brightness
+    # matrix 1
+    bus.write_reg(addr, 0x01, [
+        0xAA, 0x55, 0xAA, 0x55,
+        0xAA, 0x55, 0xAA, 0x55
+    ])
+    # matrix 2
+    bus.write_reg(addr, 0x0E, [
+        0xFF, 0x00, 0xFF, 0x00,
+        0xFF, 0x00, 0xFF, 0x00
+    ])
+    # update display
+    bus.write_reg(addr, 0x0C, 0x01)
+\end{minted}
+
+\begin{figure}[h]
+	\centering
+	\includegraphics[width=.7\textwidth] {img/phatmtx.jpg}
+	\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:
 
+\todo[inline]{add the example}
 
 
 \todo[inline]{Measurement / evaluation examples here...}