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 ).

[speculatrix]

do you mind if I add a few comments to your geek-fest?

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 proviso, I'll stick my neck out...

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!

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.

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?

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.

5) built-in sound: mono speaker, microphone for voip or dictation.

6) audio connex: stereo headphone (combined with optical out), stereo line-in (with combo optical in)... think: portable recording studio, or even oscilloscope.

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.

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.

9) serial: make a small module which can be for RS232, IRDA and JTAG, or even another bluetooth!

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


10b) touchscreen... yes please.

11a) keyboard. yes please. illuminated please!

11b) trackball? maybe?

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 :-)

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!

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).

[dhns]

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?

IMHO, you should forget about CF or PCMCIA. Most interesting CF cards are no longer in production. E.g. there is no more Audiovox GSM/GPRS or compatible to buy (besides eBay). Even Prism-based 802.11b CF cards are getting rare (others raises driver issues). GPS cards are also harder to get.

Why? Because the standard PDA or Mobile phone has one or several of them integrated. So, it is no more interesting for this accessory industry.

Finally, it makes the device unneccesarily large - IMHO.

-- hns

My first home-built PDA approx. 1985: http://www.quantum-step.com/wiki.php?page=Z80-Photos

[speculatrix]

IMHO, you should forget about CF or PCMCIA. Most interesting CF cards are no longer in production. E.g. there is no more Audiovox GSM/GPRS or compatible to buy (besides eBay). Even Prism-based 802.11b CF cards are getting rare (others raises driver issues). GPS cards are also harder to get.

Why? Because the standard PDA or Mobile phone has one or several of them integrated. So, it is no more interesting for this accessory industry.

There are still new CF things coming out - for example, Enfora only just produced a quad-band GSM/GPRS device (I didn't know audiovox dropped their gsm module). There are also CF gps units, although things are moving towards SDIO (which is useless for linux at the moment).

CF still leads the pack for flash capacity - 16GB at the moment in flash, 20GB in microdrive.

[dhns]

There are still new CF things coming out - for example, Enfora only just produced a quad-band GSM/GPRS device

Good to know a replacement for Audiovox!

There are also CF gps units, although things are moving towards SDIO (which is useless for linux at the moment).

That is what i mean to take care of. CF is leading in memory capacity and microdrives but is falling behind in I/O. And more and more I/O is being integrated.

-- hns