Understanding JCOP: memory dump

Some time ago I was struggling with JCOP smart card. The one I received as it turned out was not pre-personalized, which means some interesting features (like setting encryption keys and PIN) was still unlocked. Because documentation and all the usual helpers (StackOverflow) were not very useful (well, ok, there was no publicly available documentation at all), I started very deep search on Google, which finished with full success. I was able to make dump of whole memory available during pre-personalization.

Since it is not something that could be found online, here you have screenshot of it, colored a bit with help of my hdcb program. Without documentation it might not be very useful, but in some emergency situation, maybe somebody will need it.

JCOP memory dump made at the very beginning of pre-personalization

Small explanation: first address, I was able to read was 0xC000F0, first address with read error after configuration area was 0xC09600. I know that, despite of lack of privileges some data is placed there.

There are three configurations: cold start (0xc00123-0xc00145), warm start (0xc00146-0xc00168) and contactless (0xc00169-at least 0xc0016f). Description of coding of the individual fields is outside of the scope of this article. I hope, I will describe them in future.

Next time, I will try to describe the process of pre-personalization, that is making not pre-personalized card, easy to get from usual sources of cheap electronics, able to receive and run applets.

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A few words on everything daemon – systemd and power management overridden problem

For few weeks I had a strange problem with power management on my laptop. It is quite old Asus, really nicely supported by Linux community, so it was almost impossible to be any low-level problem. The problem was that, when I had lid of the laptop closed, system was always suspending, ignoring Plasma power management settings. This was really annoying, especially when I was leaving some background task and of course closing the lid to save power on turned off screen and then few minutes later realizing that the computer slept just after leaving it. Unfortunately I had not much time to investigate what was the reason.

Until today. It seems that systemd just started managing another part of my computer – power management. And was kind enough to ignore the fact that desktop environment is already managing it and set up its own configuration files. The effect was that it was intercepting lid close event and suspend the computer anyway.

So, if you encountered similar problem, then below are the details of what should be changed to turn that feature off.

  1. Open /etc/systemd/logind.conf with your favorite editor as root.
  2. Add following lines to [Login] section:
  1. Save and restart logind with:
systemctl restart systemd-logind.service

Now you should have gotten rid of systemd’s attempt to be the everything you need on Linux box (at least this time).

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Method for intercepting (lot of) files from website using burp

Burp exporting requests to file

Burp exporting requests to file

From time to time everyone has a need to download bunch of files from some website. Sometimes there exists one index where links to every file can be found. But sometimes not. Analysis of a website and/or figuring out a way the link is created (especially if it is something like http://some-cdn.io/directory/file-generator?param=5acae975-7784-e511-9412-b8ca3a5db7a1&ws=b0c491db-ae8b-e011-969d-0030487d8897&uid=66dba4ec-bb13-e211-a76f-f04da23e67f6&switch=1) could take months and success is not guaranteed. If this happens, downloading files manually is the only way to do it. But manual download can be optimized too.

Burp way

Burp is a sort of swiss army knife of penetration tester. Its main function is intercepting HTTP(s) traffic through built in proxy. It allows to decrypt traffic of any website or even Android app to third-party server. So this way you could configure web browser to use burp proxy and simply view every file you want to save. This would be ideal solution for backing up any image gallery including facebook galleries that can be viewed only by logged in users and uses weird links to facebook CDNs. But there is one problem. Burp does not allow to export many files at once (or at least its free license does not allow it). Or to be exact uses its own format to store both HTTP request, response and lot of metadata, we simply do not need, but we need to have directory filled with images, right?


To obey the problem, I have written simple bash script that extracts plain data from that exported data file. It gets XML file exported by Burp and unpacks plain responses, each to separate file. Usage is very simple.

  1. At first export files you want to save from Burp’s Target tab by selecting them, clicking on Save selected items and save file as whatever.xml.
  2. Then you just have to start the script with
    ./xtract-burp.sh whatever.xml

    and optionally appending desired file extension as second parameter.

Note that files will be named with iterator starting on 1 and going up and sorted the same way Burp had them exported.

As usual repo is available on github.

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CP210x (USB to TTL adapter) for Android devices

Few days ago, while searching for something interesting I can do with my Android phone I found out that Sony is publishing kernel source of all their (and old SE ones too) ROMs. Beside hacking the kernel itself I was wondering if it is possible to compile additional kernel modules (stock ROM provides only internal WiFi module’s drivers). Well.. it was. The first one I tried was driver of my cheap, Chinese USB to serial adapter based on CP2102 chip.


  • kernel source – it is important to be the same kernel as the one working on your device. Otherwise it would probably be necessary to boot your system with kernel compiled with source you have and it will not be described in this tutorial. The reason it is important is that between kernel version compatibility is not guaranteed. Different configuration could mess with functionality too (but not tried myself). I have Sony Ericsson device so I downloaded from its official repository.
  • cross-compiler – while compiling programs for Android you definitely should get special version of a compiler because Android is different than usual Linux box so compiler options are different too. The easiest way is to download official NDK which has built-in compilers and easy-to-use script to make standalone toolchain out of them. Same toolchain should also work as compiler for kernel but I haven’t tested it myself. In case it didn’t there is very powerful tool for making your own toolchain for any platform supported by GCC so in practice any you can imagine called crosstool-ng (on Arch available on AUR).
  • uucp source code

Kernel module

We will start with a kernel module. First of all we will unpack our kernel. In case of SE kernel need to be uncompressed and then unpacked so I did:

bzcat 4_1_B_0_431_tar.bz2 | tar -xv
cd kernel

And changed dir to kernel. Next thing I had to do was patching Makefile, because it complained about unused variables. If you are using Sony or SE kernel you probably need to do it too. If so create file named Makefile.patch with your favorite editor, i.e.

vim Makefile.patch

and paste following content:

--- Makefile	2012-05-25 12:07:05.000000000 +0200
+++ Makefile.new	2014-08-20 21:16:50.642703198 +0200
@@ -342,7 +342,6 @@
 KBUILD_CFLAGS   := -Wall -Wundef -Wstrict-prototypes -Wno-trigraphs \
-		   -Werror \
 		   -fno-strict-aliasing -fno-common \
 		   -Werror-implicit-function-declaration \
 		   -Wno-format-security \

Now you can patch it with:

patch Makefile < Makefile.patch

Then we can start the compilation process which should end in a second. I assume you have working toolchain in your $PATH and it is prefixed with arm-unknown-eabi- (arm-unknown-eabi-gcc, etc.). If its name is different change all occurrences of arm-unknown-eabi- below.

make mrproper
ARCH=arm CROSS_COMPILE=arm-unknown-eabi- make semc_iyokan_defconfig
ARCH=arm CROSS_COMPILE=arm-unknown-eabi- make prepare
ARCH=arm CROSS_COMPILE=arm-unknown-eabi- make modules_prepare
ARCH=arm CROSS_COMPILE=arm-unknown-eabi- make modules SUBDIRS=drivers/usb/serial CONFIG_USB_SERIAL=m CONFIG_USB_SERIAL_CP210X=m

If everything worked you should have your module compiled in drivers/usb/serial directory. It is worth to note you could compile any other module the same way. It is only important to change SUBDIRS to your module location and ensure it is configured to be built by issuing make menuconfig or setting appropriate CONFIG-* variable to ‘m’.

Now you can copy modules to your devices. With adb it will be:

adb push drivers/usb/serial/usbserial.ko /mnt/sdcard/others
adb push drivers/usb/serial/cp210x.ko /mnt/sdcard/others

We have two modules to copy here since cp210x (and any other serial device driver) depends on usbserial and without it being already in kernel it would be impossible to insert cp210x and furthermore it will give you strange error message (tested :). So now, again with help of ADB, we can insert our modules.

adb shell
cd /mnt/sdcard/others
insmod ./usbserial.ko
insmod ./cp210x.ko

After that you can connect your device and device you compiled module for and test if it works. Serial adapters should create new device file in /dev and, at least with CP210x, it uses ttyUSB* name so you can list it with:

ls -l /dev/ttyUSB*

You can also read from your port as simply as by typing

cat /dev/ttyUSB0

Now after you connect some device talking UART you should see its output.

Program to easily control our port – cu and the rest of uucp package

Warning: in the following steps I assume that you have directories like /data/local/bin and /data/local/etc already on your device. As far as I remember there is only /data/local by default.

At first we need to unpack our source and create some useful directories. Then we will configure our script in build-uucp so we won’t get garbage in source directory and could easily clean things when something goes wrong.

tar -zxvf uucp-1.07.tar.gz
mkdir build-uucp
mkdir install-uucp
cd build-uucp/

Then we will patch our program so it will work on Android out of the box. If we omitted following patch it would be necessary to create configuration file, configure program to read it before work and whole bunch of similar fun. So it is easier to let him know where he could store his files now. You can obviously use the one you want to. If you stay with my config you won’t be able to start cu as normal user which is no problem because by default you won’t have permission to use serial terminal.

Now the procedure is the same as with previous patch. I assume you used policy.h.patch name and the content is:

--- policy.h	2003-05-29 08:08:45.000000000 +0200
+++ policy.h.new	2014-08-20 12:03:45.595405893 +0200
@@ -297,7 +297,7 @@
    systems the lock files are placed in /etc/locks.  On some they are
    placed in /usr/spool/locks.  On the NeXT they are placed in
    /usr/spool/uucp/LCK.  */
-/* #define LOCKDIR "/usr/spool/uucp" */
+#define LOCKDIR "/data/local/etc/spool/uucp"
 /* #define LOCKDIR "/etc/locks" */
 /* #define LOCKDIR "/usr/spool/locks" */
 /* #define LOCKDIR "/usr/spool/uucp/LCK" */
@@ -572,7 +572,7 @@
 /* The name of the default spool directory.  If HAVE_TAYLOR_CONFIG is
    set to 1, this may be overridden by the ``spool'' command in the
    configuration file.  */
-#define SPOOLDIR "/usr/spool/uucp"
+#define SPOOLDIR "/data/local/etc/spool/uucp"
 /* #define SPOOLDIR "/var/spool/uucp" */
 /* The name of the default public directory.  If HAVE_TAYLOR_CONFIG is
@@ -580,7 +580,7 @@
    configuration file.  Also, a particular system may be given a
    specific public directory by using the ``pubdir'' command in the
    system file.  */
-#define PUBDIR "/usr/spool/uucppublic"
+#define PUBDIR "/data/local/etc/spool/uucppublic"
 /* #define PUBDIR "/var/spool/uucppublic" */
 /* The default command path.  This is a space separated list of
@@ -644,21 +644,21 @@
 /* The default log file when using HAVE_TAYLOR_LOGGING.  When using
    HAVE_TAYLOR_CONFIG, this may be overridden by the ``logfile''
    command in the configuration file.  */
-#define LOGFILE "/usr/spool/uucp/Log"
+#define LOGFILE "/data/local/etc/spool/uucp/Log"
 /* #define LOGFILE "/var/spool/uucp/Log" */
 /* #define LOGFILE "/var/log/uucp/Log" */
 /* The default statistics file when using HAVE_TAYLOR_LOGGING.  When
    using HAVE_TAYLOR_CONFIG, this may be overridden by the
    ``statfile'' command in the configuration file.  */
-#define STATFILE "/usr/spool/uucp/Stats"
+#define STATFILE "/data/local/etc/spool/uucp/Stats"
 /* #define STATFILE "/var/spool/uucp/Stats" */
 /* #define STATFILE "/var/log/uucp/Stats" */
 /* The default debugging file when using HAVE_TAYLOR_LOGGING.  When
    using HAVE_TAYLOR_CONFIG, this may be overridden by the
    ``debugfile'' command in the configuration file.  */
-#define DEBUGFILE "/usr/spool/uucp/Debug"
+#define DEBUGFILE "/data/local/etc/spool/uucp/Debug"
 /* #define DEBUGFILE "/var/spool/uucp/Debug" */
 /* #define DEBUGFILE "/var/log/uucp/Debug" */
@@ -669,17 +669,17 @@
 /* The default log file when using HAVE_V2_LOGGING.  When using
    HAVE_TAYLOR_CONFIG, this may be overridden by the ``logfile''
    command in the configuration file.  */
-#define LOGFILE "/usr/spool/uucp/LOGFILE"
+#define LOGFILE "/data/local/etc/spool/uucp/LOGFILE"
 /* The default statistics file when using HAVE_V2_LOGGING.  When using
    HAVE_TAYLOR_CONFIG, this may be overridden by the ``statfile''
    command in the configuration file.  */
-#define STATFILE "/usr/spool/uucp/SYSLOG"
+#define STATFILE "/data/local/etc/spool/uucp/SYSLOG"
 /* The default debugging file when using HAVE_V2_LOGGING.  When using
    HAVE_TAYLOR_CONFIG, this may be overridden by the ``debugfile''
    command in the configuration file.  */
-#define DEBUGFILE "/usr/spool/uucp/DEBUG"
+#define DEBUGFILE "/data/local/etc/spool/uucp/DEBUG"
 #endif /* HAVE_V2_LOGGING */
@@ -692,16 +692,16 @@
    be replaced by the system name (if there is no appropriate system,
    "ANY" will be used).  No other '%' character may appear in the
    string.  */
-#define LOGFILE "/usr/spool/uucp/.Log/%s/%s"
+#define LOGFILE "/data/local/etc/spool/uucp/.Log/%s/%s"
 /* The default statistics file when using HAVE_HDB_LOGGING.  When using
    HAVE_TAYLOR_CONFIG, this may be overridden by the ``statfile''
    command in the configuration file.  */
-#define STATFILE "/usr/spool/uucp/.Admin/xferstats"
+#define STATFILE "/data/local/etc/spool/uucp/.Admin/xferstats"
 /* The default debugging file when using HAVE_HDB_LOGGING.  When using
    HAVE_TAYLOR_CONFIG, this may be overridden by the ``debugfile''
    command in the configuration file.  */
-#define DEBUGFILE "/usr/spool/uucp/.Admin/audit.local"
+#define DEBUGFILE "/data/local/etc/spool/uucp/.Admin/audit.local"
 #endif /* HAVE_HDB_LOGGING */

If you prefer I have it on my gist so you can just issue one command and get it. Then we are patching as usually:

patch ../uucp-1.07/policy.h < policy.h.patch

As mentioned above you can change path of uucp’s files by issuing the following (remember to escape every occurrence of slash with backslash, otherwise it will fail):

sed -i "s/\/data\/local\/etc/[your-path]/" ../uucp-1.07/policy.h

Now you are ready to compile. It can be done with following commands. Your compiler should have same name (at least if you use NDK’s compiler). It is important to note that I had to switch off HAVE_SYSCONF flag since it was causing ugly errors. In my case makescript couldn’t also find a rule to make ftw.o so I had to make it myself. If you have no trouble here, just omit the line after make.

CC=arm-linux-androideabi-gcc AR=arm-linux-androideabi-ar RANLIB=arm-linux-androideabi-ranlib \
../uucp-1.07/configure --prefix=`pwd`/../install-uucp/ --host=arm-linux-androideabi
sed -i "s/#define HAVE_SYSCONF 1/#define HAVE_SYSCONF 0/" config.h
cd unix; make ftw.o; cd ..; make
make install
adb push ../install-uucp/bin/cu /mnt/sdcard/others
adb shell
cp /mnt/sdcard/others/cu /data/local/bin/

Finally you can test the program with the following and you should be able to talk RS232 with just a phone/tablet!

cu -lttyUSB0 -s115200

where 115200 is the speed the device you connect to transmits.

BTW: uucp have few other tools and by following this tutorial you compiled them all so you can explore them on your own.

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How to bypass Secure Download Manager while downloading from Dreamspark

About a month or so ago I had an urgent need to download a copy of Microsoft Windows from Dreamspark. Unfortunately I haven’t Windows installed then so had to do this using Linux. After successful transaction I was given a link to SDX file and program called SDM. It looked that it would be easy. But it wasn’t. Program that I was encouraged to download was archive with .pkg extension. As I discovered few minutes later it was OS X application package. So the next step was to try to download Windows version and try to execute it with help of Wine. It failed. Then I tried to find some tips on the Net. I found a few other people having the same problem. Some of them could download using Wine and some not. For me there was only one solution: do it myself. As you probably guessed that way was a (almost) full success.


If you already have SDC file please do not skip since you probably still don’t have a key needed to unpack the file. The first step is to open SDX file in your favorite text editor. You will see a link. Open it in a web browser. Now you need to get to page source. The way it can be done depends on your web browser. Now we need to find few strange values in the code. The easiest way to achieve this is to search for keyword ‘edv*’ where * is the number of file you want to download counting from 1 (they are on ‘Items’ list on page you opened). Now you need to copy somewhere values of the following variables: ‘oiopu*’, ‘oiop*’, ‘fileID*’ (*-see above). The last one we need is ‘dlSelect*’ but for that one you need to search cause it is in a different place. Now you can build URL that will let you to file containing two interesting values: file URL and decryption string. This URL’s format is:


Now you should see XML file that looks similar to this:


The last step here will be downloading file from fileUrl and saving edv value in file. The important thing is that the file with a key should be named exactly as SDC file with addition of ‘.key’ suffix.


I’ve just discovered that things are getting a bit different when the file size exceeds 2.0 GB. In that case Dreamspark is splitting file in two or more files. That situation could be easily recognized, because sdc file name’s suffix is: ‘.01.sdc’. In that case you need to try to download file which URL differs by only that one digit, ie. ‘.01.sdc’, ‘.02.sdc’, ‘.03.sdc’. When you encounter last file it should have smaller size than the rest and incrementing that number by one should give you BlobNotFound error.

After downloading all the files they just need to be joined into one. It can be easily achieved with dd, ie.

dd if=pl_windows_7_professional_with_sp1_x64_dvd_u_676944.02.sdc >> pl_windows_7_professional_with_sp1_x64_dvd_u_676944.01.sdc

and then optionally

dd if=pl_windows_7_professional_with_sp1_x64_dvd_u_676944.03.sdc >> pl_windows_7_professional_with_sp1_x64_dvd_u_676944.01.sdc

After that you will get sdc file prepared to unpack.

Unpacking SDC

Now since you have SDC file you can start unpacking it. The previous part was, at least for me, very easy. The problem started when I tried to discover how the file is stored in that container. But don’t worry, I’ve written simple program to do it for you. As of now (1st June) it is still in really early alpha stage and have lot of constraints. It is able to unpack containers that contains only one file packed, doesn’t create any directories, cannot verify file’s checksum and probably few other problems I don’t remember or don’t know about.

If you were searching a bit in the Internet, you probably found out that someone cracked that container in the past. Unfortunately Microsoft changed format since then. It is also possible that in response to this article it will be changed again. To make it a bit harder for them to block my software I’m publishing source code on github and after the process of reverse engineering is finished will write second article describing how things works under the hood and describe sdc file format.

But let’s get back to unpacking. Now you need to download xSDM from github. The newest version can be downloaded by typing

git clone https://github.com/v3l0c1r4pt0r/xSDM.git

in your terminal (of course you need to have git installed). Nevertheless I advice you to download newest tagged release. You can do this by clicking on releases on project page and then choosing the one on the top (or first beta/stable if any) and clicking on “tar.gz”. tar.gz can be unpacked by typing

tar -zxvf xSDM-[tag-name].tar.gz

into console. Then get into xSDM directory by typing

cd xSDM

(or your release directory) and compile the program by standard

make install

where installation is optional. Now to unpack your file you just need to type

src/xsdm [path-to-your-sdc-file]

And that’s it, you should now be able to open file you downloaded. As mentioned above the program is in very early alpha so I cannot guarantee that it will work in any case. If you will encounter any problems feel free to open issue on project page at github.

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Graphic LCD based on ST7565 chip under Raspberry Pi

Hi, today I’d like to show you how to connect and use gLCD module with Raspberry Pi as host. The display I have is only bare display without any board not like the one in Adafruit’s offer. It can be powered by 3V3 Raspberry but the display itself needs a bit more power so we will need a few capacitors to build a circuit for that purpose. It will also make the connection a bit complicated (can be seen in the photo on the right). Nevertheless I think that the process is still rather easy.


Connected display

Connected display

As far as I know ST7565 based displays can be connected on two ways: parallel and serial. In case of serial connection, which I used to save few GPIO’s, it is possible to program it using SPI or just only GPIO’s. The display that I have is a bit different than most of the others because it has external backlight, which is additionally single LED so it is very power-saving (15mA). The only problem with that backlight was that the vendor didn’t told anything about parameters of that diode so I needed to figure it out myself.. The second problem while connecting the display itself might be amount of cables that need to be connected when using breadboard. Despite these two facts the whole process should be easy.

Physical connections

Connection scheme

Connection scheme

As said before the only step that may be a bit complicated is connecting so called step-up voltage circuit, made of 4 capacitors. The capacitors that we will use are 1uF electrolytic caps. Beside that we need to use another 5 caps (same as before) to connect parallel inputs to ground. So in sum we need 9 of them. Now we only need to connect VDD to 3V3 pin on Raspberry, ground from the schematic on the right with GND pin, SDATA to SMOSI on Pi, SCLK to SCLK and A0, RST and CS to any free GPIO. It is good to remember their numbers cause we will need it in a moment 🙂 It is important to use numbers used by Linux kernel, not wiringPi which has its own names. At last we need to connect the backlight. As said I have ECO backlight so I had to connect mine using 10 Ohm resistor. You can connect it to 3V3 or if you like to have control during runtime use GPIO, just like any other LED.

Configuring the program

Now I have to mention something about a program itself, because depending on how your vendor implemented the things your display will almost surely need a bit different settings. General procedure will look the same on every ST7565-based display. Main differences will be on particular commands during setup procedure.

uint8_t init()
  if (!bcm2835_init()) {
    return 0;
  bcm2835_gpio_fsel(LCD_BACK,BCM2835_GPIO_FSEL_OUTP);		//backlight
  bcm2835_gpio_fsel(LCD_A0,BCM2835_GPIO_FSEL_OUTP);		//A0
  bcm2835_gpio_fsel(LCD_RST,BCM2835_GPIO_FSEL_OUTP);		//RST
  bcm2835_gpio_fsel(LCD_CS,BCM2835_GPIO_FSEL_OUTP);		//CS
  bcm2835_gpio_write(LCD_CS,HIGH);				//set CS to high to indicate the bus as free
  bcm2835_gpio_write(LCD_RST,HIGH);				//hardware reset
  //setup SPI
  bcm2835_spi_chipSelect(BCM2835_SPI_CS_NONE);			//manual CS control
  bcm2835_spi_setClockDivider(BCM2835_SPI_CLOCK_DIVIDER_4);	//set speed to 62.5MHz (fastest supported)
  int i;
  for(i = 0; i &lt; sizeof(initcmd)/sizeof(uint8_t); i++)
  bcm2835_gpio_write(LCD_BACK,HIGH);				//turn backlight on
  return 1;

I think that the code above should be generally clear. The most important for us is for loop that is executing every byte from initcmd array. Its content will look like that:

const uint8_t initcmd[] = 
  0xa1,							//screen orientation
  0x41,							//set starting line
  0xc0,							//page count direction
  0xa3,							//1/7 bias
  0x2c,							//vc
  0x2e,							//vc+vr
  0x2f,							//vc+vr+vf
  0x24,							//voltage regulator (0x20-0x27)
  0xa6,							//do not reverse the display
  0xaf,							//display on
  0xa4,							//display from ram
  0x81,							//turn on brightness regulation
  0x18							//set brightness (0x0-0x40)

The most important values here are:

  • voltage regulator – 0x20 means the darkest, as seen above in my case 0x24 worked
  • bias – I saw displays that had 1/9 so you need to make sure how is in yours and set it according to chips documentation linked at the end

You may also want to play with commands like screen orientation, page direction, display reverse or brightness to fit them to your needs. Now you have tell the program which GPIO you used as backlight (if you weren’t using GPIO you will now need to comment out few lines that sets backlight up), CS, RST and A0.

The program itself

To compile the program you will need to use external library named libbcm2835. It can be installed on ArchLinux ARM by issuing pacman -S libbcm2835 as root. If you are ready you can compile the program by typing: gcc -o lcd lcd.c -lbcm2835 assuming you didn’t change the filename. The simple program I’ve written, basing on the one posted on Gist by tmeissner here and ST7565’s documentation supports transferring single byte (commands too), whole framebuffer, or writing 5×8 single ASCII character or character string. Basing on both codes: mine and Meissner’s I think it is possible to do anything you could think about with that display.

Font creation

Standard ASCII table and traditional 'Hello World!':)

Standard ASCII table and traditional ‘Hello World!’:)

Ending slowly it’s time to tell something about fonts. As I said it is possible to simply write characters on the screen. To understand how all that thing works you need to know how the pixels are transfered to the display. The best explanation of the ST7565 display’s work can be in my opinion found here. TL;DR: the whole pixel space is divided into eight, 8-pixel high, horizontal pages divided into 128 columns that are 8 pixels high. If you didn’t understand, try link above. Nevertheless single letter is 8-pixel high and 5-pixel long so we need 5 bytes to store one letter. Its pixel map starts at left, top corner so it’s our (0,0) point and setting LSBof the first byte lights highest pixel. The font that is available in the code is Fixed 5×8 if someone is curious, it’s one of the default fonts in Xorg. To speed up conversion of the font to the display’s format I made simple OpenGL program to do the job for me. The code is of course available to download (check out my github).


Traditionally, at last some downloads:

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Using GNU Radio Companion – simple FM radio tutorial

This post is the second part of the Instructable mentioned on the previous post. That’s tutorial on how to make simple FM radio using GRC. That task is in my opinion the simplest project that can be made using GRC so it’s in fact beginners guide to GNU Radio which is really capable software. I hope that it is only the first my project using that software.

It isn’t hard to find GRC projects that implements FM radio functionality, that’s a fact. But when it comes to reproduce them so they are working just like SDR# you’d realize it’s a bit harder task. At least I did. I found about a three such projects but there was never any included project file and the only materials was video or pictures. I admit the video has pretty good explanation but it still wasn’t enough. The rest was even worse. They were only blog posts with few screen shots and short description. So finally to reproduce functionality of SDR#’s FM radio I had to think on my own. And after few hours I did what I tried to do.

A bit of theory

RTL-SDR Source Properties

RTL-SDR Source Properties

But let’s start at the beginning. The first thing that you need to do to start creating your own FM receiver using GRC is to find FM station that can be received without disruptions so you can check if your program works as well as i.e. SDR#. It can be done with help of SDR# and when you found one you are ready to learn some theory about FM signal processing. In fact it could be omitted, but in my opinion it is better to know a bit. I personally am not any specialist in radio theory so it will be really simple and I might be wrong somewhere so if you find any mistake in that what I will write here just let me know in comments.

The simplest FM radio consists of few elements:

  • signal source – in our case it would be RTL-SDR dongle
  • low pass filter
  • WBFM demodulator
  • audio output – your PC’s sound card

There can be few other elements depending on input and output sample rate, if it will be possible to match them using only above elements there won’t be any other. So our task will be getting signal using RTL-SDR, passing it through low pass filter and FM demodulator and outputting on PC’s sound card. Meanwhile we will also need to match the sample rate of the input to the one of the output (2 MHz in to 48 KHz out). All elements of this circuit can be found by writing part of its name while list on the right is selected. Element’s names are the ones used as section header below.

RTL-SDR source

Low Pass Filter Properties

Low Pass Filter Properties

Our signal input. We need to set its sample rate to 2M. It can be done by editing samp_rate variable and setting its value to 2e6. We need also to set the frequency of the station we want to receive. It is good practice to add every value that might be changed in the future as standalone variable. This can be done by adding Variable block from Variables category or, if you want to have possibility to edit it during the runtime block named WX GUI Slider or WX GUI Text Box and then just writing variable name as value in block’s properties.

Rational Resampler

Now we need to convert sample rate from 2M (samp_rate) to 500K which I realized is the best value for low pass filter’s input rate. To do that we need to add another variable, named i.e. quadrature, set its value to 500e3 (means: 500K). With that we need to add rational resampler’s block and set its decimation value to int(samp_rate/quadrature). Of course its input on the schematic should be connected to output of RTL-SDR Source (can be achieved by clicking on blue out on one block and then blue in on another).

Low Pass Filter

The next step is to filter out frequencies other than the one we centered in th previous step. In that task we will use a low pass filter block. We here set cutoff frequency to 100e3. This is because that’s standard band’s width. I don’t know what correct value for transition width should be, but trying to change that I found that the higher value the better so it’s finally set to 1M. Obviously it should be connected to resampler’s output.

WBFM Receive

Volume slider Properties

Volume slider Properties

Now we could do the nearly final and the most important step: placing the FM demodulator. In my case its quadrature rate equals 500k (that’s the same value as before so I set this to the value of quadrature variable). I don’t know if it could be changed to something else so if you are not sure just leave it as is. In that setting it should work.

Next Rational Resampler and Multiply Const

These elements’ job is to match the signal’s rate to the one supported by sound card and provide volume regulation. At first we need to convert rate from 500k to 48k so we need to decimate by 500 and then multiply by 48. In the second block we set const to volume. Now we can create variable or place WX GUI Slider with variable name set to volume. As you can see here color of WBFM demodulator is different than rational resampler’s and multiplier’s in and out. To change that you need to select them and use up and down arrows on your keyboard.

Audio Sink

That one’s function is to output signal on our sound card. Now its only required to edit its rate and choose 48k from a drop down list and that’s it! If you don’t have that option just choose the biggest value and edit value in rational resampler and it should work. Now you should be able to execute your program and test if it works. To hear anything it will probably be required to increase volume to about 50.

Finally: some links

If you don’t know how some part has been done or what value should have a particular variable below you can download projects that I’ve made first learning to use GRC myself and then preparing this tutorial. There is one project presented here and one made earlier.

Finished FM radio schematic

Finished FM radio schematic

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RTL-SDR under Arch Linux – getting started

First post about hardware was to be something different. Unfortunately it looks like that project already failed so it probably will never be published. Instead I’m starting, I hope series of posts, about cheap Software Defined Radio dongles based on RTL28xxU chips. This post will be short introduction to the topic of RTL-SDR and it will mostly be the same as my Instructable here.

If you get here I imply that you already know what SDR is. If you don’t take a look at Instructable linked above. Getting one is for yourself should be easy. There are lots of offers on ebay that have names of chips included in the title so you should just search for rtl-sdr and i.e. R820T. That chip is one of the most capable and cheap in contrast to E4000.


The only things we will need here is some Linux distro and of course a tuner. As Linux I recommend Arch, because of availability of packages required and simplicity of its installation. There would be good if you have better antenna for the tuner and in that case you should also have adapter to standard antenna connector.

If you are ready you can now connect your dongle to PC and check using dmesg | tail or journalctl if it is has been detected by your system and if it contains appropriate chips.

If you chose the one with R820T it is probably required to disable default dvb_usb_rtl28xxu drivers, because, at least in my case, after disconnecting the dongle system hangs and the reason is for sure fault of that particular driver. You can disable it by creating new .conf file in /etc/modprobe.d directory. It could be done i.e. by typing # nano /etc/modprobe.d/blacklist.conf in console. The file should contain one line: blacklist dvb_usb_rtl28xxu. You also need to add that file to FILES variable in /etc/mkinitcpio.conf so it looks like that:FILES=”/etc/modprobe.d/blacklist.conf” and generate new initrd file by using # mkinitcpio -p linux. Now after restarting your computer everything should be OK.

Now we will need to install few packages to make RTL-SDR up and running. rtl-sdr and sdrsharp-svn are needed for basic functionality. You probably also want to install gnuradio and gr-osmosdr-git to make more advanced things like analysis of digital signal transmitted at 433 MHz. rtl-sdr is the main driver and can be installed on Arch from community repo:

# pacman -S rtl-sdr
SDR# receiving FM station

SDR# receiving FM station

There is also its git version available on AUR as rtl-sdr-git. SDR# is the program that offers basic capability to decode FM and AM radio and have easy to learn GUI so using it is the best for beginners. It is available on AUR as sdrsharp-svn.

The most capable software for RTL-SDR is GNU Radio and its graphical tool: GNU Radio Companion. It is also available on AUR (name: gnuradio). It is also required to install package gr-osmosdr-git from AUR in order to use RTL-SDR dongle as source in GRC. Its usage tutorial is available in the next post and as continuation of Instructable mentioned at the beginning of this post.

Now if you already installed all the required software you can try to find a radio station at about 100 MHz to check if everything is working fine. As mentioned earlier you could be able to listen to only the strongest stations on the default antenna. Finding one good signal will be useful in the next tutorial. At the end I’m enclosing screenshot of SDR# with settings proper to receive FM station.

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[Android] Odblokowywanie kanałów 12, 13, 14

Jak wspomniałem w swoim pierwszym wpisie dotyczącym Androida na tym systemie niemożliwe jest połączenie się z siecią działającą na kanale wyższym niż 11 (a więc takim, który jest zabroniony w USA). Ja jednak nie mieszkam w Stanach i chciałbym, aby mój telefon miał dostęp przynajmniej do tego co nie jest w Polsce nielegalne. Na szczęście udało mi się znaleźć rozwiązanie tego problemu.

Użycie tej metody wymaga dostępu do roota, więc jeśli twój telefon nie został jeszcze zrootowany odsyłam do strony Zeely’ego. Kolejnym wymaganiem będzie zainstalowanie do folderu bin sqlite’a (nie wiedzieć czemu ten, który można używać prze adb przestaje działać gdy wpiszemy w konsoli su). Potrzebne też będzie SDK Adroida (będę używał go, aby przeklejać komendy do konsoli, nada się też każdy emulator terminala np. Terminal IDE, ale tu trzeba będzie wszystko pisać ręcznie). Radzę też żeby koniecznie wykonać backup systemu z użyciem CWM (mnie przy pierwszej próbie coś poszło nie tak i musiałem przywracać kopię z poprzedniego dnia).

  1. Podłączamy telefon do komputera w trybie debugowania USB. Wchodzimy w Ustawienia=>Aplikacje i zaznaczamy Debugowanie USB.
  2. Potem należy uruchomić konsolę Windowsa (lub terminal gdy używamy Linuksa) i przejść do folderu, w którym zainstalowaliśmy SDK. Wpisujemy adb shell. Gdy wszystko pójdzie dobrze powinniśmy być już w konsoli naszego telefonu (pojawi się znak $). Można teraz wpisać su, aby uzyskać uprawnienia roota (# oznacza sukces).
  3. Aby móc zmodyfikować folder /system należy zamontować go do zapisu. Używamy komendy mount, aby odnaleźć odpowiednie urządzenie:
    $ mount
    rootfs / rootfs ro,relatime 0 0
    tmpfs /dev tmpfs rw,relatime,mode=755 0 0
    devpts /dev/pts devpts rw,relatime,mode=600 0 0
    proc /proc proc rw,relatime 0 0
    sysfs /sys sysfs rw,relatime 0 0
    tmpfs /mnt/asec tmpfs rw,relatime,mode=755,gid=1000 0 0
    tmpfs /mnt/obb tmpfs rw,relatime,mode=755,gid=1000 0 0
    /dev/block/mtdblock0 /system yaffs2 ro,relatime 0 0
    /dev/block/mtdblock3 /data yaffs2 rw,nosuid,nodev,relatime 0 0
    /dev/block/mtdblock2 /cache yaffs2 rw,nosuid,nodev,relatime 0 0
    /dev/block/mtdblock1 /data/idd yaffs2 rw,nosuid,nodev,relatime 0 0

    Właściwa linia została pogrubiona. Wpisujemy więc mount -o remount,rw -t rfs /dev/block/mtdblock0 /system (uwaga! Wartość po /dev/block/ może być inna).

  4. Teraz przenosimy plik sqlite3 (dostępny do pobrania na końcu wpisu) do folderu, w którym zainstalowane jest adb. Otwieramy w tym samym folderze drugie okno konsoli i wpisujemy w nie adb push sqlite3 /sdcard/ czym kopiujemy sqlite3 na kartę pamięci (tutaj ważne jest, żeby karta pamięci NIE była zamontowana w komputerze tj. w trybie MSC).
  5. Wracamy do poprzedniego okna, w którym wpisujemy cp /sdcard/sqlite3 /system/bin oraz chmod 4755 /system/bin/sqlite3.
  6. Na koniec montujemy system znów do odczytu: mount -o remount,ro -t rfs /dev/block/mtdblock0 /system.
  7. Teraz możemy wpisać sqlite3 i sprawdzić czy wszystko poszło pomyślnie. Jeśli tak przechodzimy do modyfikacji właściwego pliku.
  8. Zostajemy w tej samej konsoli (tą drugą można już zamknąć). Wpisujemy: sqlite3 /data/data/com.android.providers.settings/databases/settings.db “INSERT INTO secure (name, value) VALUES (‘wifi_country_code’, ‘JP’);”. Gdybyś nie chciał odblokowywać bądź co bądź zakazanego w Polsce kanału 14 możesz zmienić JP na EU w powyższej linii.
  9. Restartujemy telefon. Gdy system włączy się kanały 12,13 i 14 powinny już zostać odblokowane i powinno być już możliwe połączenie się z siecią na tych kanałach.

Nie jestem w stanie tego teraz sprawdzić, bo już zainstalowałem sqlite3 powyższą metodą, ale najpewniej, aby dokonać jego instalacji wystarczyłoby użyć jakiegokolwiek menadżera umożliwiającego modyfikację folderu /system. Potem wystarczyłoby tym samym programem zmienić chmody tak, aby możliwe byłoby wykonywanie pliku. Tym samym możnaby wtedy pominąć punkty 3-6.

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Niedziałający mod_rewrite – rozwiązanie

Ostatnio pisząc nowy skrypt strony (tego obecnego nie można już w żaden sposób uratować bo to jeden wielki śmietnik, praktycznie uczyłem się dopiero PHP pisząc go) natrafiłem na dość poważny problem. Obecna strona używa z powodzeniem mod_rewrite, więc aby nie cofać jej w rozwoju użycie tego modułu było jednym z podstawowych celów kolejnej wersji skryptu. Niestety już po napisaniu kilku regułek okazało się, że niektóre z nich działają a niektóre nie. Początkowo próbowałem radzić sobie w możliwie najprostszy sposób używając REQEST_URI zamiast korzystać z GETa. Po napisaniu kilku podstron kontynuowanie takiego obejścia okazało się niemożliwe. Zauważyłem, że problemy sprawiają te reguły, w których jako wzorzec zawarty jest ciąg występujący również w pliku na serwerze np.

RewriteRule ^projekty/([0-9]+)$ projekty.php?strona=$1

To już dało mi do myślenia i zacząłem kombinować co jest źródłem problemu. Jak przypuszczałem zmiana projekty we wzorze na dowolny inny ciąg powodowała, że problem znikał. Trudno jednak, aby użytkownik chcąc obejrzeć moje projekty wchodził na podstronę nazywającą się blablabla lub jakkolwiek inaczej. Zmiana nazwy pliku projekty.php też nie wchodziła w grę, bo utrudniałaby tym razem moje życie. W takiej sytuacji zacząłem szukać sposobu na podejrzenie co robi serwer oraz jakie dane dostaje. Możliwe to było do osiągnięcia jedynie dzięki logom. Jako, że serwer stoi na localhoście nie stanowiło to problemu. Do konfiguracji Apache’a dopisałem:

RewriteLog [sciezka do serwera]/logs/rewrite.log
RewriteLogLevel 5

Zresetowałem i otworzyłem log. Po bardzo szybkiej analizie (większości wpisów nawet nie trzeba rozumieć, wystarczą ścieżki) zauważyłem, że moduł rewrite zamiast projekty/1 dostaje projekty.php/1. Niestety nie wiedząc jaki jest powód takiego zachowania serwera odpuściłem sobie przez co straciłem dwa dni nie pisząc ani jednej linii nowego kodu.

Kiedyś jednak musiałem do niego wrócić. Wróciłem więc dzisiaj i zacząłem analizować konfigurację Apache’a. W pliku httpd.conf nie znalazłem nic co mogłoby powodować ten błąd. Jako, że wykorzystuję WAMP’a jako platformę testową (i nie tylko, bo screeny użyte we wpisie Kilka ciekawostek z bazy whois (i nie tylko) także pochodzą z mojego localhosta tylko z zupełnie innego skryptu, którego nie mam zamiaru teraz omawiać) miałem utworzony alias do skryptu (tego od bazy whois) a strona znajdowała się dodatkowo w podfolderze (co wcześniej uważałem za przyczynę błędu, okazało się jednak, że leży ona gdzie indziej). Zajrzałem więc do konfiguracji aliasu. Wygląda ona mniej więcej tak:

&lt;Directory "x:/system/htdocs/"&gt;
    Options Indexes FollowSymLinks MultiViews
    AllowOverride all
        Order allow,deny
    Allow from all

Nie wklejam całości, żeby nie zaśmiecać wpisu. Od razu rzuciły mi się w oczy dwa elementy: MultiViews oraz AllowOverride all. Alias został wygenerowany przez WAMPa a dodatkową konfigurację pobrałem z Internetu. Trudno powiedzieć skąd wzięła się akurat ta część. W każdym razie zacząłem szukać informacji o MultiViews dzięki czemu trafiłem tutaj. Pomijając problemy jakie mógłbym mieć z Googlebotem gdyby taka konfiguracja była na serwerze dostępnym z Internetu autor wyjaśnia co robi ta dyrektywa:

Multiviews allow substitutions of file extensions, so you can call an URL like www.somehost.org/mypage.php using www.somehost.org/mypage.

Po przeczytaniu tego zdania od razu jasne stało się, że właśnie znalazłem źródło swojego problemu. Oczywiście dodając Options -MultiViews na początek pliku .htacces regułki zaczęły działać dokładnie tak jak powinny. Wniosek z tego jest taki, że gdy nie wiesz dlaczego coś nie działa zawsze czytaj logi!

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