[PD] Familiar + PDa on h5550: audio/hardware details

This mail sums up the hardware research I've been doing on the IPAQ 5550's audio/hardware capabilities using Linux over the last two weeks as part of a short residency at STEIM in Amsterdam. The aim was to set up PDa as a sound processing platform on the IPAQ: http://gige.xdv.org/pda/

__CONTENTS___________

• BASIC INSTALLATION NOTES
• GETTING THE FIRST BOOT
• SETTING UP POWER MANGEMENT
• AUDIO CONFIGURATION NOTES
• REMOTE X11 OVER SSH
• BLUETOOTH GPS
• PDa NOTES
• panDEV PROJECT PAGE

• BASIC INSTALLATION NOTES:

In general, the Familiar 0.8.1 distribution of Linux runs pretty well with the HP IPAQ 5xxx series. I am using the GPE version, but an OPIE version and a "barebones" developer version are also available.

A few tricks are employed to get it booting at first, power management needs to be properly set up and the audio needs some tweaking, but once everything has been done, you can use the Compact Flash slot, audio line-in, audio line-out, WIFI, Bluetooth and many external "jackets" without much difficulty.

Here are some older but helpful install notes: http://umbrella.sourceforge.net/article.php?story=20040311042139896

But make sure to get the latest installer files from here: http://handhelds.org/download/distributions/familiar/releases/v0.8.1/install...

Please read the release notes and installation instructions here completely before beginning as well!

It might be a good idea to take a few moments and learn how to run your terminal emulator [minicom, etc] before starting if you've never used one before, as the key commands can be tricky. Also make sure you have Ymodem installed, it's usually part of the "lrzsz" package (Debian, Gentoo, etc) and may not be installed by default with your terminal emulator package. You will get nothing but "upload failed" messages without this package!

• GETTING THE FIRST BOOT:

You may have to wait a long time for the first boot without knowing what's going on inside the IPAQ, so you might want to monitor progress with the following command in your terminal emulator after the "load root" command finishes installing the 0.8.1 image:

set linuxargs "mem=128M root=/dev/mtdblock1 init=/linuxrc noinitrd console=ttyS0"

Then type "boot" at the prompt. It may hang the first time on modprobing h5400_asic, but it should go through the next boot after that. Use the same command on the second boot as well to monitor progress.

• SETTING UP POWER MANGEMENT:

The first thing you will want to do after installing is set up the power management, otherwise the ipaq-sleep module will shut the IPAQ down every time you unplug from the charger! First do a "killall ipaq-sleep" as root, then disconnect from power and let the battery run itself out.

Then reboot with the power plugged in and don't unplug it until it's fully charged. This puts the IPAQ in Learning Mode, which will teach the power management how much time is in the battery. After this, you should be able to use the IPAQ normally.

The command "cat /proc/asic/battery" will give better battery info than the GUI if you need it. Battery "jackets", such as the Pitech MemPlug, appear to be plug-and-play, but make sure to leave them off when using Learning Mode. I use a USB Sych/Charge cable to recharge the IPAQ, as the cradle it came with doesn't seem to work at all for this purpose!

• AUDIO CONFIGURATION NOTES:

Out of the box with Familiar, the 5550 wants to play sound from the crappy built-in speaker, and record from the crappy built-in microphone.

The following binary executable switches to headphone-out and line-in:

http://hovland.org/familiar/hpswitch

Once it's downloaded, do a "chmod 755 hpswitch" as root and run it as "./hpswitch" to change the routing of the audio in and out. After this, all audio out will go the headphone jack and it will listen to the audio coming from line-in instead of the built-in mike. Other IPAQs may or may not have this speaker/jack routing problem, I think it's pretty specific to this model.

Sources of this app are available on the [h5400-port] list if anyone's interested:

http://article.gmane.org/gmane.comp.handhelds.linux.h5400/16

To use the mike jack, you will need to build the following audio adaptor:

http://web.it.kth.se/~maguire/iPAQ-photos/iPAQ-audio-adapter.html

Output is stereo, but input is mono due to the hardware. You won't get stereo input without an external card such as Core-Sound's PDAudio unit, which accepts digital sound from an outboard AD converter and can handle up to 24 bit 96 KHz stereo audio:

http://www.core-sound.com/HighResRecorderNews.html

In case any IPAQ 5xxx-series owners are *really* curious, there's a spec-sheet for the soundchip here:

http://www.handhelds.org/platforms/hp/ipaq-h5xxx/AK4535-MS0135-E-01-03-2002....

Note that "hpswitch" is used with the OSS drivers in Familiar 0.8.x for the h5xxx series. ALSA users have the alsamixer app which should do the switching for them fine. ALSA is not on the map for Familiar 0.8.2 yet AFAIK, only for the 2.6 kernel currently under development, but you can compile it from the Familiar CVS if you really want to use it. (Familiar people feel free to correct me here if I'm mistaken!)

• REMOTE X11 OVER SSH:

Patching in PDa with the IPAQ stylus is a real pain in the wazoo. I've been using a remote X11 session over SSH for this purpose in the following way:

First, edit the /etc/ssh/ssh_config file on the Host computer [i.e. your lap/desktop, not the IPAQ] and add the following line:

ForwardX11Trusted yes

I believe everything else should be commented out.

Then open a new SSH session from the Host to the Remote computer [i.e. IPAQ, webserver, etc] with the following command:

ssh -2 -X -C user@IP.address.of.Remote

Once you have a prompt inside the Remote computer, you can start X11 applications by command line:

pandev@h3900:~$ pd

Et voilà! The application's GUI will appear in the display of your Host computer, but it will be physically running on the Remote computer. YMMV as to how responsive the GUI is, as this is a function of available bandwidth IIRC.

• BLUETOOTH GPS:

When I first started working on this platform last year, one of my first questions was how to get GPS data into PDa. Have a look at the following link if you have a Bluetooth GPS to see how it can be read as serial device by GPSd in the IPAQ:

http://gpsd.berlios.de/bt.html

I'll be making a webpage on www.umatic.nl for all this info later, as Pall Thayer gave me some interesting PERL tips for GPS, and we'll be developing some Python GPS stuff as well as some WIFI tools here in Holland in the next few months.

• PDa NOTES:

A substantial bug report and comments list on the latest test version of PDa has already been submitted to Guenter Geiger and the PD-list earlier this evening, and can be viewed here: http://iem.at/mailinglists/pd-list/2005-03/026700.html I'll try running some of the objects I tested locally instead of over SSH later on and see if performance improves from what is noted already.

Perhaps this mail will be another chapter for the PDa FAQ?: http://gige.xdv.org/pda/faq.php

I'm very happy to be able to help Guenter develop PDa and to see it come further along so we all can use it. Big thanks go to STEIM for giving me the hardware, time and space to play around with! Thanks also to Jaap @ ASCII and Marc Boon for continuing programming support for the next phase of this project, and Koen Kooi and Rene Wagner on the Familiar list for expert help in a pinch.

• panDEV PROJECT PAGE:

This report was prepared as part of the development cycle of the panDEV project, a locative sound-gathering application for artists, cartographers and phonographers. More information on panDEV can be found here:

http://www.umatic.nl/projects_pandev.html