Android USB OTG HOST

Most modern Android based devices support USB OTG function [1]. USB is a Host centric bus that means there is only one Host device and many different Devices can be connected to it. Using inexpensive USB-OTG cable it is possible to swich smarphone USB port from Device to Host, and connect external devices, if chipset and OS build allows this. Google provides detailed information on how to code USB Host [2] in your application.

[1] http://www.usb.org/developers/onthego/
[2] https://developer.android.com/guide/topics/connectivity/usb/host.html

Joomla portal access recovery

In case you need to reset admin password for a Joomla install, you can do this by simply updating database record.

$ mysql5 -h <database_hostname> -u <database_username> -p <database_name>
Enter password: <database_password>
mysql> show tables;
(...)
mysql> UPDATE <database_prefix>_users SET password='d2064d358136996bd22421584a7cb33e:trd7TvKHx6dMeoMmBVxYmg0vuXEA4199' WHERE username='admin';

This will use mysql5 commadline client to connect to a given database. You will see if tables are in place. Then you will update password hash of user admin to secret which equals:

d2064d358136996bd22421584a7cb33e:trd7TvKHx6dMeoMmBVxYmg0vuXEA4199

You can also use any other database client of your choice, DBeaver is also nice utility with graphical user interface.

You can obtain necessary database access information from configuration.php file accessed by ssh/ftp on a web server.

public $dbtype = 'mysqli';
public $host = '<database_hostname>';
public $user = '<database_username>';
public $password = '<database_password>';
public $db = '<database_name>';
public $dbprefix = '<database_prefix>';

If you want to dump/backup a database into local file, use mysqldump5:

mysqldump5 -h <database_hostname> -u <database_username> -p <database_name> > dumpfile.sql

If you want to restore a database from a local file, use mysql5:

mysql5 -h <database_hostname> -u <database_username> -p <database_name> < dumpfile.sql

Google Android Nexus Device Un-Brick

GoogleNexus

If you happen to brick your Google Nexus device you can always use stock ROM images [1] to revert it to a default and operational state. Package contains not only OS but also bootloader and radio firmware images!

I have bricked my device by installing custom firmware that messed partitions layout inside a Flash Memory. I have seen lots of people having similar problem of endless bootloader-loop. There is no need to send a device to a service when bootloader is operational. All you need is a stock firmware image from Google [1], USB cable, and fastboot utility from Android SDK. If you happen to damage a bootloader, then hardware manipulation at low-level is necessary over JTAG, I can help to recover your device in that case.. no worries :-)

[1] https://developers.google.com/android/nexus/images

Android: dynamic string processing

There are two easy ways to replace text on-the-fly in Android. This may be required if you want to insert some text/values into displayed text, or construct a data packet of some sort. Both require some code to replace given part of the string.

First is to use HTML/XML tags and then handle them with your own implementation of Html.handleTag(). Unfortunately, String conversion removes the tag in the background, so you need to escape < mark with &lt; in the string resource. This approach is good when you want to put variables inside a string and then process them later in one place using tag handling – that is when you want to have a tag handled at processing time – so you only change tags and one processing routine.

Second is to use Format Strings instead of XML/HTML tags. It seems simpler, faster, and evades hidden conversion problems. getString(resource, ...) works like a well known printf(string, ...). This approach is good when you want to process each string manually at runtime, but strings and variables are hardcoded.

[1] http://stackoverflow.com/questions/7899563/android-converting-between-strings-spannedstrings-and-spannablestrings/34556513#34556513

Dualshock4 PS4 Controller Bluetooth Pairing

dualshock4-bluetooth-pair-cederom

There is one simple way I have discovered to pair with Dualshock4 Playstation4 controller using standard Bluetooth Pairing Procedure. Make sure controller is turned off, then press and hold SHARE button, then press and hold PLAYSTATION button until LED starts to blink (two short white blinks every few seconds). You can now discover and enjoy your Dualshock4 controller with any Bluetooth (HID) enabled device. No cables and no additional applications necessary! :-)

Dualshock4 is a really nice high quality and precise controller that can be used in many more interesting applications than only playing games. It is compatible with Bluetooth HID and USB HID standard. It contains 2 analog joysticks, 2 analog sliders, 13 buttons, touch-pad, accelerometer, vibrator, audio speaker with headset port, RGB LED, micro-USB port, and external expansion port..

Unfortunately, lack of self-compatibility seems to be a strong disadvantage of Playstation platform. Not only because PS4 does not run old software. Dualshock4 seems to have different way of handling button events as compared to Dualshock3 (default Playstation3 controller). It has some sort of auto-repeat feature (like PC BIOS keyboard) instead of button change events (like MIDI). This renders Dualshock4 unreliable on Playstation3 platform because of massive control glitches. Also DS4 PS button does not produce system menu on PS3, so you cannot use it as the main controller replacement. Sadly, it is impossible to use DS3 controller on PS4 as well. Hopefully, switching CPU to AMD64 and OS to FreeBSD could bring more self-compatibility to Playstation in future..

Fixing corrupted GPT backup

When you setup system on a fresh disk you may encounter a problem of corrupted GPT backup. This will happen even more likely when you messed with MBR before on that disk. Free and Open GDISK utility will help you. GDISK will tell you current state of the disk and partition tables, also warn you on possible problems. When you print available partitions (‘p’) and they seem okay, you can simply write out (‘w’) the partition table, that would fix the GPT backup corruption problem :-)

Mac OSX USB installer

In order to create OSX installer on USB memory drive you need to:

  • Download the Mac OSX Yosemite installer from AppStore on you Mac.
  • Create installation media from Terminal by executing following command (remember to adjust YOURUSBVOLUME value):

    sudo /Applications/Install\ OS\ X\ Yosemite.app/Contents/Resources/createinstallmedia --volume /Volumes/YOURUSBVOLUME --applicationpath /Applications/Install\ OS\ X\ Yosemite.app --nointeraction
  • Boot target Mac from USB by pressing ALT/OPTION key while powering-on the computer.
  • Remember to format target drive first with Disk Utility if you want to perform clean installation.

Mac OSX Bluetooth Modem resource busy

In case you wonder why your device does not connect as Modem via Bluetooth to the Mac OSX, or you cannot see COM port on Windows, your mobile device may not simply support or provide DUN (Dial Up Network) and/or SPP (Serial Port Profile) profile.

On Mac OSX I got following error, until I tried another device and/or starting by hand DUN service on a mobile/client machine:

cannot open /dev/cu.Bluetooth-Modem: Resource busy

Notes:

  • Read Bluetooth specification for Serial Port Profile.
  • Read Bluetooth specification for Dial-Up Network Profile.
  • Modern mobile phones / USB 3G dongles, unfortunately, do not provide direct AT/Hayes access to the Radio Modem anymore.
  • You can install DUN application for your smartphone, but it will be only a simple dummy wrapper imitating modem for simple applications, but they do not provide full modem functionality, beware, its a fake.
  • Its only necessary for devices to be paired first in order to get SPP/DUN working. If device does not provide serial port over bluetooth when devices are paired and online, probably its just not there implemented.

OSX 10.10 Yosemite install/runtime problem

If you want to perform a fresh installation of OSX 10.10 Yosemite on an older MacBook(Pro) you can obtain the installer with AppStore and then create the USB installation media.

In case you encounter an Installer Verification Error that prevents you from installing the new system try the following. Its not the system date not bad download as internets says.

This may also help you when encountering problems (i.e. USB Mass Storage) after system upgrade to Yosemite.

Try these boot keyboard shortcuts until you hear boot sound two times:

  • Cmd+Alt+R+P when powering on the Mac (NVRAM Reset)
  • Alt+Ctrl+Shift+PowerON alltogether (SMC Reset)

No problem, you are wolcome :-)

FreeBSD + PPP + GSM/3G/LTE Modem

If you want to use GSM/3G/LTE modem on your FreeBSD box you need to use PPP and following configuration:

default:
 set log Phase Chat LCP IPCP CCP tun command
 ident user-ppp VERSION 
 set device /dev/cuaU0
 set phone *99\#
 set redial 5 10
 set speed 115200
 set dial "ABORT BUSY ABORT NO\\sCARRIER TIMEOUT 5 \
           \"\" ATH OK ATZ OK AT OK-AT-OK ATE1Q0 OK \
           AT+CFUN=1 OK-AT-OK \
           AT+CPIN? READY-AT+CPIN=\"1234\"-OK \
           AT+CGDCONT=1,\"ip\",\"internet\" OK \
           \\dATDT\\T TIMEOUT 40 CONNECT"
 set timeout 10
 enable dns
 set ifaddr 10.0.0.1/0 10.0.0.2/0 255.255.255.255 0.0.0.0
 add default HISADDR

GRUB2 default boot menu entry

Q: How to change the default boot menu entry in GRUB2 used widely on Linux systems?

A: You can do it easily as root in three following steps:

  1. Run update-grub program and copy entry name that you want to make default.
  2. Edit /etc/default/grub and add or modify existing GRUB_DEFAULT="your_menu_entry_here".
  3. Run update-grub program again to update the grub bootloader configuration.

Screenshots in Android 4

If you wonder where did the power menu option to make a screenshot go in Android 4 – you need to long press Power + Volume Down buttons together :-)

Still I don’t know how to disable screen inside ongoing call when my Power button is assigned to end call, or how to end call when screen is locked and Power button is assigned to lock screen ;-) Design Fail or hidden solution somewhere there deep inside..? Apple simply use one button to end/diall call and separate mechanical switch to lock the device – simple functional and elegant.. but hey why Android does not use this solution as well, is “button switch pair” already patented by Apple? ;-)

YouTube and HTML5

I have found very simple solution on how to access YouTube videos that require Flash using HTML5 player. Although front site may not support HTML5 video player, YouTube usually allows to embed videos to other sites, they also should use WebM codec developed by Google. If you have a video that does not work in HTML5 by default try to run it in embed player by URL modification – replace “/watch?v=” with “/embed/” and it should work! :-)

Example: http://www.youtube.com/watch?v=M84Y6VXAIaU -> http://www.youtube.com/embed/M84Y6VXAIaU