Build Your Own Linux Powered Pda Options

[Tom61]

I've had the idea about rolling my own Linux powered PDA for some time, but I've been busy with another project of mine. So, I haven't posted about this idea, but recently Da_Blitz posted:

the iMX3 is a custom PDA idea as the 2700G chip is VERY hard to get. dont want to hijack this thread anymore so if you want more info then contact me direct or make another post

Definately looking for some more info on that!

Here's some interesting ideas to get the thread started:

GumStix ( www.gumstix.com www.gumstix.org ): Very small, proprietary, stackable modules. Very hobbyist friendly, but current models are still based around the Intel PXA255.

Colibri Module : PXA270 with most of the needed chips built in, and connections for most of the rest, in a formfactor of a DDR SODIMM. Moderately hobbyist friendly, with boards only 119Euros for the 520MHz version, but with a fixed handling fee for Hardware of 100 EUR and shipping of 45 EUR. You'll want to order more than one to be price effective with this supplier.

CM-X270 Computer-On-Module: I stubbled on to this site last night. No idea about this supplier's ablity to handle hobbyists, or even the cost of the module. However, you can configure a pretty impressive COM on that page. Up to PXA270 520Mhz, 128MB of RAM, Intel 2700G with 8MB of its own RAM, audio codec, and 512 MB of NAND flash!


Take a look at the Google Ads when you do a search for 'Arm development board', as quite a few Ads hit the mark for what we would want, if they could be had cheap, and single unit quanties (which most aren't ).

[stampsm]

[quote=speculatrix,Jun 19 2006, 02:08 PM]do you mind if I add a few comments to your geek-fest?[/QUOTE]
sure



[QUOTE]if possible, make everything modular to take advantage of commodity items... e.g. SD memory cards are falling in price and gaining in capacity, USB bluetooth dongles have allowed easy upgrade from bluetooth 1.0 to 2.0.

However, this generally increases size (connector), decreases reliability (connector) and increases power (interface/glue electronics).

So, with that provison, I'll stick my neck out...[/QUOTE]
modular is good but it has a drawback of size (big consern for a PDA), extra power draw(very big consern for a pda), external connections (the same thing will happen that happened to my wireless card. you keep in plugged in just once and you put the pda in your pocket and sit down..... snap goes the card )


[QUOTE]1) two SD slots - make sure they're full-speed; one will be the system disk, the other for removable storage. three would be better![/QUOTE]
planned two sd cards since they are small in size and the processor has two ports for them already.


[QUOTE]2) minimal flash memory - LOADS of ram (384 or 512M), a small boot rom and boot the device from an SD card. It's also much easier for people wanting multi-boot devices to switch or for developers to test their kernel/system builds. Even better, use a DIMM socket for RAM - benefit from commodity prices.[/QUOTE]
i agree on the use external memory idea, but ther is a problem. most NAND chip manufacturers have stopped or slowed making chips under 128MB in size. RAM IS GOOD that being said 256MB is about the most i think we can stuff into this as it supports 4 chips max (someone verify this) and the mobile DDR chips come in 512Mb (64MB) max that i have seen. hence we can only get 256MB max. socketed chips are bad for stuff like this since they are very large in comparison


[QUOTE]3) two CF card slots, or one CF + one PCMCIA.



NOTE! a PCMCIA interface doesn't have to be big - as long as you don't mind the card sticking out! make the slot *just* deep enough for a CF card with adaptor. These card slots can be used for wifi, gps, ethernet, GPRS or 3G card, high performance audio adaptor

this also opens up pcmcia sata adaptors and other interesting things! It also alleviated the need for a full backpack system?[/QUOTE]
the processor supports 1 ata/pcmcia slot and 1 CF slot. so the you can have one CF slot and possible another CF slot and have on the bottom a expansion port for the full pcmcia port (pcmcia backpack?) that that disconnects the second CF and takes over (must see if this is possible)



[QUOTE]4) mobile phones vary too much world-wide and suck too much current - rely on bluetooth link or a CF adaptor. as things move to 3G or 4G/Wimax/wibro, a gsm adaptor will become as useless as IRDA.[/QUOTE]
i slightly agree since the clamshell design is not very good for a phone and if you need mobile data connectivity...bluetooth to the resue... , but i have not had enough experience designing boards so da-blitz would be the final decision maker on this. note: if you did add a phone to this the cost would go up and it would make it a bluetooth only device most likely.


[QUOTE]5) built-in sound: mono speaker, microphone for voip or dictation.[/QUOTE]
of couse speakers are a must (mp3 ) and a microphone would be also. they would take up very little space and exery PDA have them now days



[QUOTE]6) audio connex: stereo headphone (combined with optical out), stereo line-in (with combo optical in)... think: portable recording studio, or even oscilloscope.[/QUOTE]
stereo headphones would be a must. microphone in is one of those nice but not a pass or fail feature. you could add an oscilloscope but is it really practical on a pda??????



[QUOTE]7) wireless: built-in bluetooth 2.0 with A2DP for stereo headphones!
wifi: built-in or module? I'd say rely on CF adaptor or usb, cheap, removable, offers choice of 11a/b/g/n without worrying about becoming a legacy interface like wifi.[/QUOTE]
i dont see bluetooth changing much in the future while maintaining it's stand on low power short range use, so integrating bluetooth should be no issue. a bluetooth chip capable of stereo audio is something that is a very good thing to work for. as for the 11g access i would see it staying around for a while with the large market it has already in infastructure. plus if something new came out in 3-5 years you could add it with the CF slot.



[QUOTE]8) USB: at least two USB2.0 full-speed host and one client (so can be used as slave for usb networking or mass storage). Consider also firewire as this allows connections to video devices as well as mass storage.[/QUOTE]
well the processor has 1 OTG USB (host and slave) and two host USB. the OTG would be external for sure, but the two just plain USB would most likely be used for internal connections such as USB and 11g. we could add doccumented contact points though so hardware hackers could have fun.



[QUOTE]9) serial: make a small module which can be for RS232, IRDA and JTAG, or even another bluetooth![/QUOTE]
serial is a must especially for debugging. i think the processor supports 5?? serial ports total (though some may be multiplexed) , so 1 serial external plus possibly a few with contact points on the board for hardware hackers




[QUOTE]10a) display. well, I think in a sense this is the easiest choice, and provided you pick the right driver chip and interface, means you can go for a range of devices with QVGA, VGA and higher (such as the Lifebook P7120). Must be daylight readable.

The key here is to allow video acceleration without sucking power, so the video accelerator has got to be capable of operating in a very low power mode.

You could also not have an LCD display but instead the new M1 connector and a head-up display!
http://www.presentersuniversity.com/visuals_visuals_PDA.php[/QUOTE]
VGA display is a definate goal. for size we are most likely looking at 3.5 up to max of 4 inches. i found two displays at 640x480. one 3.7 inch and another the same but it was a 4 inch model.(they have the same interface i think so you can design off of that and when we start doing the case design we can plug in the most appropriate display) some people were looking into an external display port of some sort but we will have to make sure that it is feasible. head-up display??? if you have that much money can i have some.





[QUOTE]10b) touchscreen... yes please.[/QUOTE]
yes and built into the lcd i was looking at.



[QUOTE]11a) keyboard. yes please. illuminated please![/QUOTE]
keyboad yes think clamshell zaurus design. illuminated hmmmm with some of the slim led's i have seen it is a definate possibilty. even if we could not put backlighting for the keyboard we could put a few led's on the display part so the could light up the keyboard.



[QUOTE]11b) trackball? maybe?[/QUOTE]
very small in size so it wont take up to much room. plus it is a unique feature i could see other pda's adopting in the future




[QUOTE]12) other peripherals:
12a) accelerometer - do microdrives have this built-in?
12b) camera?
12c) ethernet?
12d) math co-pro/ssl accelerator/dsp
12e) I/O expander module for industrial control (A/D, D/A, parallel I/O using I2C), monitoring and measurement.
12f) printer/floppy drive/geiger counter/microwave oven (just checking if you read this far :-)[/QUOTE]
a) nice feature and takes very little space maybe 8x8 mm if pc board space. we could add contact points with no issue and then decide latter if we want to populate in. this also give hardware hackers more fun.
camera nice since there is hardware built in to the processor to help this, but i have been trying to figure out where you would put it to be usable.
c)ethernet possible but wired connections are being superceeded by wireless and those few who need ethernet could buy a CF ethernet card
d)the processor has a built in 3d graphics chip plus floating point math, so i dont see this as much needed
e)io expander... well if we add a docking like port with the pcmcia line that really opens it up since it could include data lines to allow custom hardware for this and software to be added.
f)
printer, use USB(drivers needed) irda(drivers needed) bluetooth(drivers needed) 11g(drivers needed). basically we need drivers so existing USB drivers in linux are the most likely to be usable
floppy, use USB (drivers needed)
other stuff......well good luck stuffing that in





[QUOTE]13) backup-battery - use a small supercapacitor, just so you can switch batteries without losing work. this was a bug-bear with my 860. Also need a good battery control circuit (like Sony's infolithium), with good input protection so you can charge it from almost any power source![/QUOTE]
good idea using a supercap, or better yet use a 2032 battery or some other Li watch battery so you could "sleep" the pda and use it to keep ramother stuff powered while you change batteries.




[QUOTE]well, that's my dreaming over with! wake me up when I can buy one.




actually, seriously, I think it's perfectly doable... the hardest part of all? Making it PDA sized.




The flybook is an example of what can be achieved, but then it's GBP1500 or over US$2500! I often ponder that it's too big for a PDA, too small to be a laptop (and the Zaurus would be a better PDA, and the Lifebook 7120 would be a better laptop).[/QUOTE]

the goal is to have hardware cost about c3000 range or less but give more


ok i am done for now

[speculatrix]

[quote=stampsm,Jun 20 2006, 01:05 AM]
[QUOTE]if possible, make everything modular to take advantage of commodity items... e.g. SD memory cards are falling in price and gaining in capacity, USB bluetooth dongles have allowed easy upgrade from bluetooth 1.0 to 2.0.

However, this generally increases size (connector), decreases reliability (connector) and increases power (interface/glue electronics).

So, with that provison, I'll stick my neck out...[/QUOTE]
modular is good but it has a drawback of size (big consern for a PDA), extra power draw(very big consern for a pda), external connections (the same thing will happen that happened to my wireless card. you keep in plugged in just once and you put the pda in your pocket and sit down..... snap goes the card )
[/quote]

erm, you agreed with my "however" there.

[quote]
i agree on the use external memory idea, but ther is a problem. most NAND chip manufacturers have stopped or slowed making chips under 128MB in size. RAM IS GOOD that being said 256MB is about the most i think we can stuff into this as it supports 4 chips max (someone verify this) and the mobile DDR chips come in 512Mb (64MB) max that i have seen. hence we can only get 256MB max. socketed chips are bad for stuff like this since they are very large in comparison
[/quote]

yeah, sockets are not practical. many of the latest memory devices are BGA, which makes it much harder to retrofit memory expansion... hence why I thought an SODIMM socket might be better than on-board RAM. Also, there are sodimm sockets which raise the memory up high enough so there's room for chips on the PCB underneath, so you actually gain PCB real estate.
example:
http://www.crucial.com/store/partspecs.asp...PN=CT64M64S4W75

[QUOTE]
the processor supports 1 ata/pcmcia slot and 1 CF slot. so the you can have one CF slot and possible another CF slot and have on the bottom a expansion port for the full pcmcia port (pcmcia backpack?) that that disconnects the second CF and takes over (must see if this is possible)
[/quote]

does anyone remember Handspring - their add-on modules were virtually pcmcia modules with a slight tweak to allow them to charge a price premium - people found out how to take a pcmcia/cf adaptor and use non-proprietary memory cards etc.

[quote]
[QUOTE]4) mobile phones vary too much world-wide and suck too much current - rely on bluetooth link or a CF adaptor. as things move to 3G or 4G/Wimax/wibro, a gsm adaptor will become as useless as IRDA.[/QUOTE]
i slightly agree since the clamshell design is not very good for a phone and if you need mobile data connectivity...bluetooth to the resue... , but i have not had enough experience designing boards so da-blitz would be the final decision maker on this. note: if you did add a phone to this the cost would go up and it would make it a bluetooth only device most likely.
[/quote]
adding a phone also massively increases getting the device approved for sale in many countries - I think the flybook uses a Siemens GSM module rather than a custom GSM tranceiver made from discrete components - but this adds more bulk and battery load.

[quote]
[QUOTE]5) built-in sound: mono speaker, microphone for voip or dictation.[/QUOTE]
of couse speakers are a must (mp3 ) and a microphone would be also. they would take up very little space and exery PDA have them now days
[/quote]
speakers small enough for a PDA are worthless - a mono speaker is fine for telephony. Oh yeah, need to be able to remote-control the PDA from the headphones. This remote control circuit can have other uses too.

[quote]
stereo headphones would be a must. microphone in is one of those nice but not a pass or fail feature. you could add an oscilloscope but is it really practical on a pda??????
[/quote]
microphone in IS imperative for VOIP headset - as you said, clamshell is not the right shape for holding up to your ear. Analogue input without DC blocking allows basic oscilloscope functions - sure, not high bandwidth, but even a megahertz is useful for students.


[quote]
[QUOTE]13) backup-battery - use a small supercapacitor[/QUOTE]
good idea using a supercap, or better yet use a 2032 battery or some other Li watch battery so you could "sleep" the pda and use it to keep ramother stuff powered while you change batteries.
[/quote]
a supercap is fine, trust me, and doesn't need replacing like a 2032.