224 lines
8.1 KiB
TeX
224 lines
8.1 KiB
TeX
This section describes how to implement Efsl on a AVR $\mu C$ connected to
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an SD-Card (SPI). For getting efsl to compile, the avr-gcc compiler and
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avr-libc library are required. On Windows you should install WinAVR
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(http://winavr.sourceforge.net/), on Linux you can install the packages
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separately (see http://www.nongnu.org/avr-libc/user-manual/install\_tools.html
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for a nice howto).
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\subsubsection{Hardware}
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First, you need set up a prototype in which you connect the CD, CMD, DAT0
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\& CLK lines from the SD-Card to /CS, MOSI, MISO \& SCK from the Atmega.
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\newline
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\includegraphics[scale=0.65]{pics/sdcard.eps}
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\newline
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%\parbox[c]{.4\textwidth}{\begin{center}\includegraphics[width=.4\textwidth]{pics/sdconnection}\end{center}}
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\parbox[c]{.5\textwidth}{
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Connect the following lines on the SD-card:
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\begin{itemize}
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\item{Pin 9 (DAT2) - NC\\(or pull-up to 3.3V)}
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\item{Pin 1 (CD) - Any pin on the Atmega128}
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\item{Pin 2 (CMD) - MOSI\\(pin 12 on the Atmega128)}
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\item{Pin 3 (Vss) - GND}
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\item{Pin 4 (Vdd) - +3.3V}
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\item{Pin 5 (CLK) - SCK\\(pin 11 on the Atmega128)}
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\item{Pin 6 (Vss) - GND}
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\item{Pin 7 (DAT0) - MISO\\(pin 12 on the Atmega128)}
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\item{Pin 8 (DAT1) - NC\\(or pull-up to 3.3V)}
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\end{itemize}
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}
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\parbox[c]{.5\textwidth}{\begin{center}
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\includegraphics[width=.5\textwidth]{pics/sdconnection}
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\newline\newline
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Remark: this schematic includes pull-up's to 3.3V, which
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can be left off.
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\end{center}}
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\newline
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Remark 1: Make sure that your $\mu C$ is running on 3,3V, so you don't
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damage your SD-Card.\newline
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\newline
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Remark 2: CD is currently static set to PB0, but will become variable
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in future releases.
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\subsubsection{Download \& Compile}
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Let's get started:
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\begin{enumerate}
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\item{Get the latest release of efsl on http://www.sf.net/projects/efsl/}
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\item{Unpack the library (on Windows, you can use WinACE or WinRAR)}
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\item{Copy in directory \filename{conf} the file
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\filename{config-avr.h} to \filename{config.h}}
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\item{Copy in directory \filename{conf} the file
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\filename{config-avr.makefile} to \filename{config.makefile}}
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\item{Compile the library (\code{make avr})}
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\end{enumerate}
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Now you should have the following files in a directory called {lib}:
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\begin{itemize}
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\item{\filename{libefsl-base.a}}
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\item{\filename{libefsl-fs-vfat.a}}
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\item{\filename{libefsl-prot-sdspi.a}}
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\item{\filename{libefsl-hwd-atmega\_spi.a}}
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\end{itemize}
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\subsubsection{Example}
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Since Efsl itself is only a library, it's not supposed to do anything out of
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the box, than just compile. To get started, we'll show here a small example
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program that opens an existing file and writes the content to a new file.
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\newline\newline
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First, create a new directory in which you put the compiled efsl-library
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(\filename{libefsl.a}) and create a new file called \filename{avrtest.c} containing:
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\lstset{numbers=left, stepnumber=1, numberstyle=\small, numbersep=5pt, tabsize=4}
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\begin{lstlisting}
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#include <efs.h>
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#include <sd.h>
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#include <atmega_spi.h>
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void hang(void);
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void main(void)
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{
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efsl_storage_conf storage_conf;
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efsl_fs_conf fs_conf;
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efsl_storage storage;
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efsl_fs fs;
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File file_r;
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File file_w;
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atmegaSpiInterface spi_interface;
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SdSpiProtocol sd_protocol;
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char buf[512];
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unsigned short e;
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/* Init */
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spi_interface.pinSelect=0x01;
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sd_protocol.spiHwInterface=&spi_interface;
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sd_protocol.spiHwInit=(void *)atmega_spi_init;
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sd_protocol.spiSendByte=(void *)atmega_spi_send;
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storage_conf.hwObject=&sd_protocol;
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storage_conf.if_init_fptr=(void *)sd_Init;
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storage_conf.if_read_fptr=(void *)sd_readSector;
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storage_conf.if_write_fptr=(void *)sd_writeSector;
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storage_conf.if_ioctl_fptr=(void *)sd_ioctl;
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storage_conf.ioman_bufmem=0;
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fs_conf.no_partitions=0;
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fs_conf.storage=&storage;
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if(efsl_initStorage(&storage,&storage_conf)){
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hang();
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}
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if(efsl_initFs(&fs,&fs_conf)){
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hang();
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}
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if(file_fopen(&file_r,&fs.filesystem,"orig.txt",'r')!=0){
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hang();
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}
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if(file_fopen(&file_w,&fs.filesystem,"copy.txt",'w')!=0){
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hang();
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}
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if(file_fopen(&file_r,&efs.myFs,"orig.txt",'r')!=0){
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hang();
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}
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while((e=file_read(&file_r,512,buf))){
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file_write(&file_w,e,buf);
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}
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file_fclose(&file_r);
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file_fclose(&file_w);
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fs_umount(&fs.filesystem);
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hang();
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}
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void hang(void)
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{
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while((1))
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_NOP();
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}
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\end{lstlisting}
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$ $\newline
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Some extra information on the code above: TODO
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%\begin{itemize}
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% \item{Line 1: The header file for efsl is included here. When using the
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% basic efsl functions, \filename{efs.h} is the only header file on the
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% efsl library that needs to be included.}
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% \item{Line 7: The object efs is created, this object will contain
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% information about the hardware layer, the partition table and
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% the disc.}
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% \item{Line 8: The objects \code{file\_r} and \code{file\_w} are created, these objects
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% will contain information about the files that we will open on the
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% efs-object.}
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% \item{Line 9: A buffer of 512 bytes is allocated. This buffer will be
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% used for reading and writing blocks of data.}
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% \item{Line 12: Call of \code{efs\_init()}, which will initialize the efs-object.
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% To this function we pass:
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% \begin{enumerate}
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% \item{A pointer to the efs-object.}
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% \item{A pointer to the file that contains the partition table /
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% file system (in this example, we select a device as file).}
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% \end{enumerate}
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% If this function returns 0, it means that a valid fat partition is
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% found on the SD-card connected.
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% If no valid fat-filesystem is found, or the file does not exist, the
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% function returns a negative value. In this example we then go to an
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% infinite loop to prevent the program to continue.}
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% \item{Line 16 \& 20: Call of \code{file\_fopen()}, which will initialize the
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% file-objects. To this function we pass:
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% \begin{enumerate}
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% \item{A pointer to the file-object.}
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% \item{A pointer to the filesystem-object.}
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% \item{A pointer to the filename.}
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% \item{A char containing the the mode (read, write, append).}
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% \end{enumerate}
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% If this function returns 0, it means the file has successfully been
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% opened for reading / writing / appending.
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% If the file could not be opened (because for example a file already
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% exists), a negative value is returned.}
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% \item{Line 24: Call of \code{file\_read()}, which will read a given value of
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% bytes (in this example 512) from a file and put it's content into
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% the buffer passed (in this example called buf). This function returns
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% the amount of bytes read, so the while-loop will be executed as long
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% as there are bytes left in the file.}
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% \item{Line 25: Call of \code{file\_write()}, which will write a given value
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% of bytes (in this example, the amount of bytes that was read
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% by \code{file\_read()}) from the buffer passed to a file. This function returns
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% the amount of bytes written.}
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% \item{Line 28 \& 29: Call of \code{file\_fclose()}, which will close the
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% file-objects.}
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% \item{Line 31: Call of \code{fs\_umount()}, which will write all buffers to
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% the the SD-card.}
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%\end{itemize}
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\subsubsection{Testing}
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So now let's test the program:
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\begin{enumerate}
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\item
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{ Compile the program:
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\begin{itemize}
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\item{On Linux (with avr-gcc): avr-gcc -I/home/user/src/base/include -I/home/user/src/include -I/home/user/src/fs/vfat/include -I/home/user/src/hwdrivers/atmega\_spi/include -I/home/user/src/protocols/sdcard\_spi/include -I/home/user/conf -ffreestanding -mmcu=atmega128 -Os -o avrtest.o avrtest.c -L/home/user/lib -lefsl-base -lefsl-fs-vfat -lefsl-hwd-atmega\_spi -lefsl-prot-sdspi}
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\item{On Windows (with WinAVR): replace all slashes with backslashes}
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\end{itemize}
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}
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\item{Generate a hexfile
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(avr-objcopy -j .text -j .data -O ihex avrtest.o avrtest.hex)}
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\item{Connect an SD-card to your Atmega128 with a file called
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\filename{orig.txt} on it.}
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\item
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{
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Flash the hex file into your $\mu C$.
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\begin{itemize}
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\item{On Linux: avrdude -P /dev/ttyUSB0 -c stk500 -p m128 -Uflash:w:avrtest.hex}
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\item{On Windows: use Atmel AVR-Studio}
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\end{itemize}
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}
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\item{Reset your $\mu C$ and wait some time (depending on how big
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the file \filename{orig.txt} is).}
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\item{Disconnect the SD-card, so you can put it in your card reader
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and find out if the file \filename{orig.txt} is copied to
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\filename{copy.txt}.}
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\end{enumerate}
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