Practical Computer Matters

HTC P3470 (Pharos)

I've (not so recently) bought a HTC P3470 (Pharos) smartphone / PDA. This device combines combines mobile phone, satnav, and organiser functionality. However, the jack of all trades is a master of none... there are things that remain to be wished for. My current unresolved issues include:

• File transfer: I can use the obexftp program to transfer any file via Bluetooth from my Linux laptop to the P3470. However, getting files doesn't work, unless the files are .vcf or .vcx files.
• GPS logging: I'd like to create traces of my movements with GPS, e.g. to contribute to the Open Street Map project. However, I haven't found an application that works reasonably.

Probably I could have spared myself from these troubles by getting a Freerunner from openmoko. I'll seriously consider that if they release a model with GPS.

Setting up Bluetooth on Linux (Debian)

My main interest in bluetooth is for file transfer, I haven't tried using a mobile phone as a modem (for accessing the Internet), or as a speaker / headset etc. Setting up Bluetooth was relatively straightforward for me:

• get a USB Bluetooth dongle
• Debian packages I've installed and which I think are required to use Bluetooth:
  • bluetooth
  • bluez-hcidump
  • bluez-utils
  • libbluetooth2
• run tail -f /var/log/messages and connect the dongle to the computer. The message usbcore: registered new interface driver hci_usb indicates that the dongle has been recognised correctly.
• turn on Bluetooth on the mobile device, and make the device discoverable (on the HTC P3470, go to Settings -> Connections -> Bluetooth -> Mode for this). Then, run hcitool scan to find out the MAC address of the device.
• Debian specific: Compile the passkey agent, provided in /usr/share/doc/bluez-utils/examples. I've put the compiled program in /usr/local/bin for convenience. Then, run passkey-agent --default some key.
  • The bluetooth subsystem must be up for the passkey-agent to work.
  • The passkey agent is necessary to establish the first connection, but it may not be necessary subsequently.
• If the device allows file transfer (on the HTC P3470, use Settings -> Connections -> Bluetooth -> FTP), you can use obexftp to list files on the mobile and to transfer files -- if the mobile device cooperates. (The HTC P3470 doesn't, see above).

Bluetooth File Transfer

Files can be "pushed" from the HTC P3470 to the Linux box by running

 hciconfig hci0 piscan
 obexpushd -B

on the Linux box, and then choosing to "beam" the file.

Nokia N900

Recently I got myself a Nokia N900. I'm still in early stages of exploring it. So far I quite like it. Being able to ssh into my mobile is really neat and useful. X11 forwarding from the N900 to e.g. a laptop doesn't work, however, as there's no xauth program on the N900 (or I haven't found one yet).

Unfortunately it seems that the N900 does not currently work too well with external Bluetooth keyboards. Apparently there are some X11 keymapping issues.

Some useful links:

• GNU Emacs for the N900
• Maemo talk (user forums)
• Maemo SDK
• Writing Apps for the N900
• OpenJDK for ARM

Digital Images

The exiftran application enables lossless and EXIF aware rotation of JPEG images. Rotating images according to their EXIF orientation tag is particularly useful:

 exiftran -i -a *.jpg

The exif application displays the EXIF (Exchangeable Image File Format) information contained in JPEG images, and it can also extract thumbnail images from such JPEG files.

Encrypted File System Setup

• Encrypted Device Using LUKS