Build Your Own Linux Powered Pda

[Da_Blitz]

The chip i mentioned is 24Bit @ 192Khz, the other thing to note is that alot of audio codecs are about that size, i want one that requires few external components so we will see, open to sugestions if others find chips, and no FM kay thats it for today from me

[morrijr]

A minimal 'backup' OS which is always available or a hard-wired copy from [insert media type here] would be useful so the device isn't brickable.

Otherwise - nice device.  I'd certainly give it some thought (wrt buying one!).

[Da_Blitz]

I lied and read some documentation instead of sleeping:

Backup OS has been discussed, it is a kexec'ing kernel that bootloads the next stage for you (using a lin kernel as grub or lilo) you will hopefully be able to set it up to load only kernels that are signed with your private key (have your public key in flash), im doing this way because we can, the bottloader / will be Read only (enforced in hardware so you cannot stuff it up) and include as a minimum busybox, fsck for several FS gpg (for signed kernels) and a SSH server, that should be enough to keep you out of trouble

heres the low down on the sound chip:
Standby current 2mA
full power down 890uA
everything on (full 5.1, mic inputs and SPDIF) 218mA
all DACs 71mA (normal usage would be 1 of the 4 DACS so 40mA)

has bass and treble control, 24bit @ 192Khz, can do 7.1 but i plan to aim lower, supports SPDIF, built in volume control and mute (no clicks) and can be connected to various busses, it also can act as a analog audio switching matrix to route audio from other chips to the outputs, (ie sound from phone), the iMX3 can do this for digital as well

this is overkill and i will probelly use a smaller chip when i run out of board space (hahha) but i am checking the amount of PCB we will need' keep in mind we will have chips on the top and bottom if i can get it done so the board density is going to be huge

[speculatrix]

hdmi can do VGA and DVI so its a universal solution, heck it can do vide out as well for connecting to a

I might be wrong (has been known :-) but although DVI can carry both digital and analogue signals in the same connector, it doesn't have to - it was a compromise; if there's only digital, you'd need a D/A convertor.

I think HDMI is similar; I think the way forward is for digital flat panel interfaces, so analogue VGA is 2nd choice.

[speculatrix]

well fm audio is not really needed alot. for those who use it there are CF adapters for it or even plain radios that are really sinple and the size of a pen or so. plus think about how much space it along with all the extra components take up. useing the size of a 100 pin tqfg package that the chip comes in to figure out the size of the evaluation board ( i did not see and info on size so i "figured" it out) it seems like it is about 6x8 inched in size. even if  it was stripped of all unessesary stuff i can still see it taking up 5-6 sq inches. do we got enough room?
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FM radio is a dying standard in UK/Europe, where DAB and DRM (digital radio mondiale) are taking over, and pocket radios are very cheap, so I think this might be a distraction... also digital hash from the zaurus would probably make it quite hard to get a clean signal!

[Snappy]

btw, just saw this link ... wonder if its any useful ...

SLD PXA PCBoard - Small Linux Device
http://www.hw-server.com/hw_products/sld_hws.html

Let me know if its already in the thread and I'll delete it.

[speculatrix]

btw, just saw this link ... wonder if its any useful ...

SLD PXA PCBoard - Small Linux Device
http://www.hw-server.com/hw_products/sld_hws.html

Let me know if its already in the thread and I'll delete it.
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quite an interesting board, I think the PXA255 is now officially obsolete (and with Intel trying to sell their Xscale division) parts will become harder to find... a PXA270 or 275 is now the baseline, but in this thread better alternatives have been found more suited to the high peripheral integration of a PDA.

well done for finding it, it can give us inspiration... and also suggests that our motherboard could be commercialised and sold with support and fund future developments.

[speculatrix]

I found this and posted it in a different thread...
http://www.dspdesign.com/products/index_html?category_id=55

don't know how much it costs - they didn't answer my email!

the other aurora board has more to offer but is probably too big:
http://www.dspdesign.com/products/product_...?product_id=133

yes, they have a linux sdk for them.

[dhns]

impressive, amazing, exciting. but really feasible?

Everything is feasible - its just a matter uof how much money you want or can afford to spend (compared to xyz)...

-- hns

[desertrat]

Heh, one last note: The stylus: Anyone think they can make Laserpen styli?

If you mean a laser pen stylus that will fit into the existing pda silos then I don't think it's possible as there are no batteries that small (not sure how small the laser mechanism can be). If you mean something like the picture attached then these are pretty cheap, less than 2USD in bulk. This particular model is 15cm long, has a laser, an led torch, pen  and stylus.

 [ Invalid Attachment ]

[Ferret-Simpson]

heh, Lithium-Ion cell sheets are 23 microns thick, and appear to work like a parallel plate capacitor (This morning, discovery channel) No-one think we can't build a 2 inch long spiral LION cell? Doesn't have to be a HUGE power to power a laserpen. XP

It was a JOKE, anyway.

Anybody who dislikes cats:
http://ars.userfriendly.org/cartoons/?id=2...08&mode=classic

Hey, 7.1 chip would be good, It would give 5.1 as well as internal stereo. Not to mention 24/192 is insane!

One idea would be to have either a 2.5mm nokia-type output, or (If room fits) a pair of 3.5's for Stereo and Mic, and have a small connector to an external hot-pluggable breakout box for the other speakers? Would make it possible to use all channels with standard equipment while taking a minimum of board and case real estate. The SP/DIF could be on the box too. (I'm an MAUDIO Delta 66 user) Just a thought. But remember, we'll need two separate outputs for internal speakers to do it properly, otherwise we'll need to disconnect the headset to get speaker-use on phone or music. Which is technically unsatisfying as a solution.

Also, I was thinking about it, and a system like this, is going to have alot of sound interfaces. External 5.1, Internal phone, internal speakers, internal mic, Bluetooth headset. . . Hell to manage that number of interfaces. And since we're probably going to be using GPE and pdaXrom, why not port the Jack server and QjackCTL? It handles high sample rates, is pretty interconnectible, and  QJCTL has the cool "Connections" window to link Inputs to Outputs.

What would the system drain from it be like? I'm guessing not too big, compared to say KDE services.

As soon as sound is working on Poodle2.6, I'll betatest it on OZ/GPE! (Obviously that being if someone wants to port it. I can;t code to save my life.)

Ferret.

[Da_Blitz]

I have always wanted to try Jack but never really understood what its for and why i should use in over an alsa.conf file in my home dir

the chip can do 5.1 out with the extra outputs as a seperate interface (eg speakers) however this chip only has 2 ADC's that can be sourced from 8 diffrent locations external to the chip.

this chip has limitations that need to be addressed if we use it but i cant get an acurete picture of the sound chip until i know whta other parts we will be using, still need a bluetooth chip, wifi, gsm, hdmi transmitter.... if you want to help start looking for those parts as i can only do about 1 part per 2 days plus my searches turn up the same thing again and again whereas some people have found things i hvent seen yet

spdif is supported by the chip but its inclusion will depend on how much space we have aroud the side of the case, if there is none i will try and put it on the docking station

[speculatrix]

One idea would be to have either a 2.5mm nokia-type output, or (If room fits) a pair of 3.5's for Stereo and Mic, and have a small connector to an external hot-pluggable breakout box for the other speakers?

Sorry to repeat myself, but I think one of those 3.5mm stereo jacks which is ALSO an optical s/dif connector would be better. have two, one for headphone and digital out, one for line input/digital in.

A third connector could be (stereo?) microphone input with remote control functions like the Nokia four-ring-tube headsets?

plugging in the headphones could mechanically disable the onboard speaker, or better, the mixer to speaker driver can be turned off by software.

[speculatrix]

this chip has limitations that need to be addressed if we use it but i cant get an acurete picture of the sound chip until i know whta other parts we will be using, still need a bluetooth chip, wifi, gsm, hdmi transmitter.... if you want to help start looking for those parts as i can only do about 1 part per 2 days plus my searches turn up the same thing again and again whereas some people have found things i hvent seen yet

there are various tiny bluetooth modules; here's a Mitsumi WML-C09 against a millimetre scale ruler:

http://www.zaurus.org.uk/images/wml-c09-measured.jpg

the VITAL thing is to ensure the product is fairly new otherwise it could be discontinued; this is particularly significant since [a] lead-free regulations have caused a lot of older modules to be dropped change from bluetooth 1.0->1.1->1.2->2.0?? means older ones are being dropped. At least with a module there's  a good chance of being able to find a pin-compatible one.

Here's the prism2/3 usb module from the 6000:
http://www.zaurus.org.uk/images/6000_wifi_lifted.m.jpg
(in this next pic it's shown in the screen mount cutout)
http://www.zaurus.org.uk/images/6000_under_screen.m.jpg

Hope this helps,
Paul

[Snappy]

Actually, if given a choice, I would go for a PXA255 or maybe 270 and a ATI accelerator video chip. If the drivers can be setup properly, the acceleration can overshadow a faster cpu in performance.

And in any case, performance in most scenarios that we use our Zaurus for requires processing of multimedia. I really don't hear much folks doing intensive mathematics on their Z ...