Build Your Own Linux Powered Pda

[Nemuri Neko]

Well on reading the datasheet again, it appears that it will overlap transactions depending on the order that they appear, whilst it does overlap the SDRAM acceses to a large degree, the other acceses will complete before a new one is issued. This will only affect the system throughput if multiple masters are trying access differing resources. If the graphics subsystem is doing an access to SDRAM at the same time as the CPU wants flash, the CPU will stall until the SDRAM transaction had finished.

The arbiter will allow both the CPU and GPU to have queued transactions to SDRAM, but in the above case the CPU would still be stalled if the GPU was doing a transaction to SDRAM and then the CPU issued a transaction to SDRAM, but the impact would be less.

Perhaps we should stay on topic as this really doesn't affect the design too much  

[speculatrix]

maybe we should conference on skype sometime?

alternatively, if everyone was a subscriber to sipgate.de/sipgate.co.uk we could phone each other for free using our zauruses and kp/pi!

[lardman]

irc....

https://www.oesf.org/forums/index.php?showt...ndpost&p=135019

Si

[dhns]

kexec can execute any binary image regardless of what it is. as long as it runs on the hardware it can exec it (this is how tho openBSD peopel boot on the Z)
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That is good. I am thinking about porting a Darwin kernel to the ARM processor. Is challenging but appears feasible (sources of Darwin are very well structured).

And using kexec would be a really nice way to boot.

Where can I find more documentation (the ones I find with Google are not enough), e.g. kernel file format, where it is loaded to, where is the binary for the Zaurus Sharp ROM, etc.

-- hns

[Da_Blitz]

i keep getting "no such channel" when i connect on irc. probelly doing somthing wrong at my end

to some extent it does affect the design. it is intresting as it tells us what will take a performance hit and what wont. but does it apply when you stick the flash on an 8bit interface? from what i read doing that causes no shared pins at all. WEIM sounds great but it still sounds as if we need a bit of translation logic, i will have to break out a data sheet or two and look at how to wire it all up

can you give me a page number where it talks about which pins are shared and which are not as i remeber seeing one but cannot find the page anymore

kexec info should be on the arm linux website, i dont know tho full details but i assume its fairly simple. there wouldnt be a file format, only where you get loaded to and the location of the command line args

[Nemuri Neko]

i keep getting "no such channel" when i connect on irc. probelly doing somthing wrong at my end

to some extent it does affect the design. it is intresting as it tells us what will take a performance hit and what wont. but does it apply when you stick the flash on an 8bit interface? from what i read doing that causes no shared pins at all. WEIM sounds great but it still sounds as if we need a bit of translation logic, i will have to break out a data sheet or two and look at how to wire it all up

can you give me a page number where it talks about which pins are shared and which are not as i remeber seeing one but cannot find the page anymore

kexec info should be on the arm linux website, i dont know tho full details but i assume its fairly simple. there wouldnt be a file format, only where you get loaded to and the location of the command line args
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The problem is the data is spread over 3 documents. The pin sharing is in a document called MCIMX31 and is on page 56. The MCMX31RM also has a far more complicated version on page 16-14

NAND does have a dedicated io bus. If you have a look at the operation of NAND it does not have an address bus or data bus, but an I/O bus. This carries both commands and data. So you issue a read on the I/O bus, then wait, then do a read ( or write ) on the same bus, the same pins. It is easy to wire up if you have a nAND controller, but is really not efficient.

The WEIM doesn't really need much external circuitry. It might need a buffer on the low 12 address pins to de-couple the devices from the SDRAM so it doesn't add any additional capacitive load to the SDRAM.

DB: I'll do a full bandwidth comparison of the 2 busses if you like. Fancy having a go as well just to make sure we get it right

[Tom61]

Picking the keyboard now seems to be getting the cart before the horse (and when is the last tiem you saw a horse pushing a cart?), as you need a good idea of the handheld to fit the keyboard.

Anyways, here's an easy to pick up one that might work, and it's decently easy to get one as a normal person:
http://flickr.com/photos/tom61/160165223/

It's from a Sammy PS2 minikeyboard and gamepad (see the rest of the photoset), designed for games like Phantasy Star Online. It works like any other USB keyboard.

[Ferret-Simpson]

Ok, when I was looking at the keyboard I was basing it on the Nokia Mobile phone keypad style. Small SMD microswitches with a rubber keypad over the top, transparent so that light can pass through and sprayed with an opaque colour for the places where it's not meant to. This is held over the keyswitches by a frame of metal (or plastic in the nokia's case) that stops the keys falling out.

The good thing about this is that we could use denser rubber for a firmer keypress, as well as make the keys thinner, with a broader surface area, to get your larger keys and make the whole unit smaller.

And it makes the backlight easier. ^^

Edit: Stamp, we have a basic idea of the layout of the PDA, if not what shape the ends are. XD

[Da_Blitz]

mmm very nice keyboard you have there. does it work if plugged into a computer (joysticks and all) if so i would go and grab one (just what i need more stuff on my desk). it may seem silly to some extent to be chosing a keyboard this early however it helps me to specify the elctrical interface to the keyboard, do you want to have an adaptor or just plug it into the board, are they even elctrically compatible with the keyboard scanning matrix?

i like your camparison however if we know what horse we are buying or we already know the girth of the hourse and how strong it is then it would be safe to say that we can make a good estimite as to the cart we will need

i think we will have to get one made. i urge you all to go back and have a look at the linx i gave to see what type of capabilities they have.

mmm seems the problem i had is only refering to the RM, will take a look at the rest tonight. i didnt see that picture. things look good and i will have to study that a bit more. the CF card may go back on the CF controller depending on how much toruble it causes

yes things are finally starting te get technical  we really need real time chat, i will look into freenode to set up a room as it didnt work when i tried to connect. the other option is skype or IM. if its skype then i will put my x30 to good use

seems i can rig the thing to boot somehow from external mem. we will see how that affects what i have proposed in terms of boot security. it may effect the authentication part of the boot

i dont know if we really need a bandwidth comparison as it really comes down to te flash chips we use and if they do not share the data pins then we should be fine

ok looking at the docs the data pins for the FLASH and the sdram are on sepearate busses Wohoh!!!" the bad news (not really that bad) is that the NAND, WIEM and PCMCIA all share the same data pins (pg 16-21 in the RM) therefore i think it may be worth brininging back the CF slot over putting the CF on the ATA interface as this then gives us more options

the disadvantage of this is that copying from flash to CF or CF to flash will be slower as both are acsessed at the same time. also with the flash interface say we put the flash on the WIEM we can then go higher speed and wider (32bit anyone) however looking at it it does have a maximum area that each CS can handel (thereby limiting the amount of flash in the sytem).

i think we need to look at each CS and decide what we use each one for so we can then decide on the memory map oy the PDA (might as well do it scince we can) and then from that detirmine how much flash and RAM will go into the system and decide on which chips we will use

and last of all i would rather put the flash on the nand intergace, there seems to be some stuff for flash such as WP that makes it handy for the bootloader stuff. if it works how i belive it does we may be able to update the bootloader and then disable writing to the flash via a hardware register (the overview seems to indicate this)

[Ferret-Simpson]

I don't wanna slower CF! ;_;

heh, I'd prefer the CF over ATA because all I'm going to use it for is bootup.

External, hotswappable CF expansion is completely pointless for anybody except those who have cameras etc with CF. In that case I think you're likely to get a better data rate over a USB reader anyway.

16MB/s versus 66MB/s is a much bigger deal when my OS is going to be running of of it. Even if it IS just "Theoretical," I'd rather have a bigger bandwidth overhead for new, improved cards to be released.

Now that I understand the flash boot properly, I'm also going to vote for the original plan of a secure bootloader on 16MB RO flash.

Is the account for the kphone Zaurus VOIP free? If so then I'm happy to get one and use that, after al my 5600 has the inbuilt Mic/SPK, and the wireless card I now have should enable it. Skype was always temperamental on my linux box, and I've never used IRC.

Ferret_Simpson Iha4._te_Yu()MrSpammer@Sodarnmuch@hotmail.com for MSN

and FerretSimpson for my AIM account.

[Da_Blitz]

sorry forgon ta adress ferret's keyboard post

i said next to each other with no gap however for tactile feedback i assemed the dome stylu keys that the c3000 uses, even when these are next to eachother with no gap due to the rounded bevel nature there would be a tactile feedback of the boarders of each key

the other advantage would be larger keys as in the cold my hands dont work nearly as well  this would easily allow us to iouble the size of each key and would mean we could just cut a rectangular area out to insert the key which means easier case manufactuer

next we have to decied, plastic keys over the membrane or rubber membrane keys. with the first the light would come from the inside of the letter and would be harder to make, however in some ways it is nice as it makes it easier to change keyboard layouts (remeber i am a dvorak user). just let the user glue the keys in whatever location they please

with membrane the letters would be "lettery" and darkened with the light coming form around the letter (see the treo for an example) the rubber is nice for some people but i know that some dont like the tactile feedback it gives

to do both would mean differing key hights which is not nice. however the LED's are inuversal between the two and the mebrane defuses the leds over the entire area

the first way i mentioned is how nokia tends to implemnt thier "hard button" keys (the plastic ones) while the second way is the same as the first but we dont add the plastic tops

anyway i want to go with the metal dome as it gives the tactile feedback we all want (i presume its universal?)

keyboard links from ealier: http://www.melrose-nl.com/membraneswitch.html
http://www.newenglandkeyboard.com/

[Da_Blitz]

dont expect a new CF format to be specified any time soon and even if it is i dont think i could make the exsisting hardware compatible

the speed is actually kind of a joke, its sort of like Hard drives at the moment. they all say 300MB/s for SATA 2 however not one drive can reach that speed and all can work just as fast on SATA (150MB/s) it does reduce the latency for transfer of all tho data however

for this i belive i will ask the only one with experince on how to solve this (neko you there ) he might have some input aon an issue like this however if you feel  strongl about it post here and tell me why

remeber this is not YOUR PDA but OURS (to no person in piticular, i must say that to myself once in awhile)

[Ferret-Simpson]

I just think there should be a slightly more "visible" split between the keys, even if it's just grooves in the one-piece keyboard. The harder the keys, the better the feedback, right?

And colour of the keyboard? Same as the colour of the unit. If we use alu casing, alu keytops. And the advantage of the nokia design is that the keypads are removeable, so that if you wanted to change to Dvorak, or GB, or US, or FR, or whatever you want at a later date, you can. Seems a bit against our design plan to make a completely upgradeable, replaceable PDA, except for the keypad which is glued down.

o.o

I guess it's for simplicity of manufacture, right?

If we look at the XDAE, (Jasjar, Qtech 9000 Yada yada Yada. . .) They seem to have what you're talking about. Fixed dome keys, but with grooves between them. I've tried it, and it's a nice keyboard. Perhaps it would be better to just glue the entire chosen keypad onto the membrane, rather than individual keys. Just have a few different layouts. . . US, GB, DVORAK. . Anyone here want any other keyboard layout? If so, say now. XD

[speculatrix]

next we have to decied, plastic keys over the membrane or rubber membrane keys. with the first the light would come from the inside of the letter and would be harder to make, however in some ways it is nice as it makes it easier to change keyboard layouts (remeber i am a dvorak user). just let the user glue the keys in whatever location they please

the 6000 keyboard is about as small as possible to be used (the lack of number keys is its biggest problem), albeit I have medium sized hands but someone with chunky fingers would have a real problem. It's reasonably tactile, so somethign similar but with all the shift/control and number keys would be the smallest sensible keyboard.

the 860 keyboard was, for me, pretty much perfect in terms of size/spacing, and was merely "ok" tactile-wise

I find the Nokia hard plastic keys to be quite pleasant, I've got a 6310i still going strong

so my vote would be for a keyboard that combines these three characteristics

[speculatrix]

Is the account for the kphone Zaurus VOIP free? If so then I'm happy to get one and use that, after al my 5600 has the inbuilt Mic/SPK, and the wireless card I now have should enable it. Skype was always temperamental on my linux box, and I've never used IRC.
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sipgate is free to sign up, and best of all unlike other VOIP providers you get a "real" telephone number (geographic one) unlike many where you get one which costs callers a premium rate - so it can be free for people to call you. It confused people when I rang them and they saw the number and thought I was home, despite explaining I was in a hotel in Phoenix Arizona!