no offence but i see you as misintrperting alot of the stuff i have said (leave the keyboard out of this
) personally your personal needs dont bother me, alot of it has helped push the platform into somthing other than "PDA". there are a couple of unseen motivations driving this board that i have not mentioned, for example this board has 3 I2C busses but i dont intend to have I2C devices in the project but run them to headers for one of my other projects where you need 3 busses (5 would be better)
there is good reason for splitting that way, logical design is one of them (or the zen of design). battery packs would use the same case as the keyboard, brining down the cost of such item
it allows for very easy hotswap of batteries. designing a battery holder for a removebale battery is not easy and not somthing i would look fowrd to, by making the battery unit semi self contained it allows me more internal room and to cut much neede thickness off of the design.
it also assists in heat managment. at the moment if the cpu and the battery were in the same case the battery would be over the top of ethier the bluetooth chip, power supply, cpu or wifi chip. these all generate heat. heat causes lithium battries to explode (lithium bieng the second most volitile element known to man after potassium, actually i wonder how much power you could get from a potasium battery
it really makes changing a battery easy, just slide it off and slide a new one on.
there are problems with the design, i am aware of that. one is multiple battery packs, that would mean you would have to purchase multiple IO boards. this needs thinking i can see several solutions but each has advantags and disadvanteges
with no battery in the CPU board the thickness of the base unit is about 4mm plus lcd screen thickness (4mm) plus case (about 2 mm) for comparison i mesure the c3000 screen at 8mm and the keyboard at 18mm
the battries i am looking at are 3.6v. at the current size i am looking at they cover 2x the area of a c3000 battery and are 1/2 as thick and are 2200maH. this relates to a power rating of 7.92W which is a bit more than a Z. the reason for calculating power and not beothering with voltage and current is that i am using a power converter in this design to reduce wasted power/losses
eg if you use a normal regulater to drop 5v @ 1A to 3v @ 1A you "lose" 2W ((5V-3V)*1A) now considering that the input power is 5W and the optput power is 3W you can see a loss of 40% of the power.
now before you start looking at the Z and wondering if thats where your battery life is going let me say its more complex than that and that the Z is probelly using the same tecnique as me to get a bit of extra power.
anyway back on topic, if i can get a battery as big as the screen then i would be happy, sure it will be pushed up againston IO board that produces heat as well but at least in the event of faliure you only lose the battery pack, the risks are minimised as well by the fact that the IO board should generate less head
ethier way i think i will push for usb audio if i can get it, it means more flexibility in design. i do intend to include sound on board if i can and i bileve that there is a good chance it will be however the modular bays are somthing that could make the customisation asspect easier and alot cheaper for all of us.
i did say audio but perhaps thats a bad thing as its a feature that everyone expects to have. but wifi and to a lesser extent bluetooth may be good choses for this. GPS is another as well as supprise suppries the phone. by making the phone a module it means that the sparkfun modules make it to my "to be considered list"
might add that i bought a HP rw 6828 pda pdone. its good but the one problem i have with it is that the that the headphones jack has alot of noise from everything else on the PCB, by modulrising everything in a common bay configration it allows me te come up with better RF shielding as i only have to do it for one cage and apply it to the rest.
IO boards are designed like PCI, ie just slot in no soldering required. i was thiing between a matchbox size and a 1/2 matchbox size unit.
also want to run this by you guys because its intresting, some new phones/pdas use the usb port as the headphone jack. what do you think. is this a good idea?