stlink/doc/tutorial/tutorial.tex

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\begin{document}

\title{Using STM32 discovery kits with open source tools}
\author{STLINK development team}
\date{}

\maketitle

\newpage
\tableofcontents
\addtocontents{toc}{\protect\setcounter{tocdepth}{1}}


\newpage

\section{Overview}
\paragraph{}
This guide details the use of STMicroelectronics STM32 discovery kits in
an opensource environment.


\newpage

\section{Installing a GNU toolchain}
\paragraph{}
Any toolchain supporting the cortex m3 should do. You can find the necessary
to install such a toolchain here:\\
\begin{small}
\begin{lstlisting}[frame=tb]
https://github.com/esden/summon-arm-toolchain
\end{lstlisting}
\end{small}

\paragraph{}
Details for the installation are provided in the topmost README file.
This documentation assumes the toolchains is installed in a \$TOOLCHAIN\_PATH.


\newpage

\section{Installing STLINK}
\paragraph{}
STLINK is an opensource software to program and debug the discovery kits. Those
kits have an onboard chip that translates USB commands sent by the host PC into
JTAG commands. This chip is called STLINK, which is confusing since the software
has the same name. It comes into 2 versions (STLINK v1 and v2). From a software
point of view, those versions differ only in the transport layer used to communicate
(v1 uses SCSI passthru commands, while v2 uses raw USB).

\paragraph{}
Before continuing, the following dependencies are required:
\begin{itemize}
\item libusb-1.0
\item libsg2
\end{itemize}

\paragraph{}
The STLINK software source code is retrieved using:\\
\begin{small}
\begin{lstlisting}[frame=tb]
git clone https://github.com/texane/stlink stlink.git
\end{lstlisting}
\end{small}

\paragraph{}
The GDB server is called st-util and is built using:\\
\begin{small}
\begin{lstlisting}[frame=tb]
$> cd stlink.git;
$> make ;
$> cd gdbserver ;
$> make ;
\end{lstlisting}
\end{small}


\newpage

\section{Building and running a program}
A simple LED blinking example is provided in the example directory. It is built using:\\
\begin{small}
\begin{lstlisting}[frame=tb]
cd stlink.git/example/blink ;
PATH=$TOOLCHAIN_PATH/bin:$PATH make ;
\end{lstlisting}
\end{small}

\paragraph{}
A GDB server must be start to interact with the STM32. Depending on the discovery kit you
are using, you must run one of the 2 commands:\\
\begin{small}
\begin{lstlisting}[frame=tb]
# STM32VL discovery kit
$> sudo ./st-util /dev/sg2

# STM32L discovery kit
$> sudo ./st-util
\end{lstlisting}
\end{small}

\paragraph{}
Then, GDB can be used to interact with the kit:\\
\begin{small}
\begin{lstlisting}[frame=tb]
$> $TOOLCHAIN_PATH/bin/arm-none-eabi-gdb
\end{lstlisting}
\end{small}

\paragraph{}
From GDB, connect to the server using:\\
\begin{small}
\begin{lstlisting}[frame=tb]
$> target extended localhost:4242
\end{lstlisting}
\end{small}

\paragraph{}
By default, the program was linked such that the base address is 0x20000000. From the architecture
memory map, GDB knows this address belongs to SRAM. To load the program in SRAM, simply use:\\
\begin{small}
\begin{lstlisting}[frame=tb]
$> load blink.elf
\end{lstlisting}
\end{small}

\paragraph{}
GDB automatically set the PC register to the correct value, 0x20000000 in this case. Then, you
can run the program using:\\
\begin{small}
\begin{lstlisting}[frame=tb]
$> continue
\end{lstlisting}
\end{small}

\paragraph{}
The board BLUE and GREEN leds should be blinking (those leds are near the user and reset buttons).


\newpage
\section{Notes}

\subsection{Disassembling THUMB code in GDB}
\paragraph{}
By default, the disassemble command in GDB operates in ARM mode. The programs running on CORTEX-M3
are compiled in THUMB mode. To correctly disassemble them under GDB, uses an odd address. For instance,
if you want to disassemble the code at 0x20000000, use:\\
\begin{small}
\begin{lstlisting}[frame=tb]
$> disassemble 0x20000001
\end{lstlisting}
\end{small}


\subsection{libstm32l\_discovery}
\paragraph{}
The repository includes the STM32L discovery library source code from ST original firmware packages,
available here:\\
\begin{small}
\begin{lstlisting}[frame=tb]
http://www.st.com/internet/evalboard/product/250990.jsp#FIRMWARE
\end{lstlisting}
\end{small}

\paragraph{}
It is built using:\\
\begin{small}
\begin{lstlisting}[frame=tb]
$> cd stlink.git/example/libstm32l_discovery/build
$> make
\end{lstlisting}
\end{small}

\newpage
\section{References}
\begin{itemize}
\item http://www.st.com/internet/mcu/product/248823.jsp\\
  documentation related to the STM32L mcu
\item http://www.st.com/internet/evalboard/product/250990.jsp\\
  documentation related to the STM32L discovery kit
\end{itemize}

\end{document}