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So now that the voting has completed, it's now time to actually decide on the exact parts to get! Smile

We have to decide on parts for these features:
- 3.5 mm link cable/port
- 192x128 screen
- Arrow keys for directional input
- AA battery (rechargeable if possible) for power
- Alpha lock for alphanumerical and symbol input
- Backlit screen for viewing in dark places
- Mini USB for file transfers between calc and PC (or calc to calc)

Oh, and don't forget the CPU! Wink OTZ80 will be using an eZ80 50 MHz CPU... but there's certain specs for each one.

Main eZ80 part site:
http://www.digikey.com/PTM/PTMPartList.page?site=us&lang=en&ptm=6200&WT.z_ptm_structured=Buy%2520Now%2520Button

List (I think):
http://search.digikey.com/scripts/DkSearch/dksus.dll?Selection&c=39&f=205&ptm=6200&site=us&lang=en&cshift_ck=null&client_id=5042

Also, a major priority is the screen. Why? For this resolution, it's a bit hard to find, plus they're really expensive sometimes.
If you find a good screen, make sure:
1) You can really trust the supplier. Others YOU KNOW (and/or other users on forums) can say "Yes, I've had no problems with this supplier." Otherwise, it's not a good thing to do.
2) It doesn't look ugly. The last thing we want is people saying that the calc's screen is ugly! Razz
3) The backlight can be turned on and off. Must have.
4) The backlight can change colors... (optional)

Note that they CAN be separate as well.

Happy hunting (and discussing)! Very Happy
Regarding the backlight, I'm gonna take the opposite stance and say that the colorful backlight idea would be bad. That would require an LED backlight, which sucks down a lot more power than an EL backlight, which is what I think we should try to get. I think we should definitely be willing to abandon the backlight in favor of a cheap, good-resolution screen if our best option otherwise lacks a baclight.

Quote:
- 3.5 mm link cable/port
That will be trivial. I don't think there's any point in getting one with a switch to detect when something is plugged in.
Quote:
- 192x128 screen
See above.
Quote:
- Arrow keys for directional input
Are we going to do PCB + membrane + discrete keys like TI? A membrane pad (bad idea imho)? Discrete buttons soldered on, an expensive and dual-PCB proposition? I think the first would be best.
Quote:
- AA battery (rechargeable if possible) for power
Bah. Case would have to contain the holder somehow, probably, the way the TI case is molded.
Quote:
- Alpha lock for alphanumerical and symbol input
See keypad comment.
Quote:
- Backlit screen for viewing in dark places
See first paragraph.
Quote:
- Mini USB for file transfers between calc and PC (or calc to calc)
Again, a trivial part.

What about Flash and RAM?
For the backlit screen, I agree, but only if it's really really necessary. Wink
For keys, probably like TI, but maybe prettier? Wink
And maybe the case is molded in, depends.

Flash and RAM... I was kinda referring to the CPU, since they have memory (I think) builtin.

Of course, we can always add a flash chip on top of that (reliable one, that is). Any thoughts on the CPU's memory and the external flash?
The ez80 has 16MB RAM built in? Can you cite a source for that information? Is there Flash?

Regarding the keys, what are you thinking re: "prettier"? And definitely the case will have to be molded, but probably with key apertures like the TI case.

You really love your backlit screen a lot, don't you? Smile

By reliable Flash, I suppose you mean high-wear-level? I don't know of a lot of chips offhand; I assume we'll have to deal with powers-of-two like 128MB, 256MB, etc. I think that 128 or 256MB is more than enough, personally.
KermMartian wrote:
The ez80 has 16MB RAM built in? Can you cite a source for that information? Is there Flash?

Regarding the keys, what are you thinking re: "prettier"? And definitely the case will have to be molded, but probably with key apertures like the TI case.

You really love your backlit screen a lot, don't you? Smile

By reliable Flash, I suppose you mean high-wear-level? I don't know of a lot of chips offhand; I assume we'll have to deal with powers-of-two like 128MB, 256MB, etc. I think that 128 or 256MB is more than enough, personally.


I might be reading specs wrong, but from what I see:
64KB (64K x 8 ) FLASH
4K x 8 RAM

Source: http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=269-3874-ND

As for keys, maybe better shapes and color? Wink Definitely should look MUCH better. Wink

And yes, I love the backlit screen. Wink Pretty nice to have. The Casio has a very pretty, blue backlit screen that's very crisp. Where's that youtube vid when I need it... Razz (Omnimaga site is 403ing at the moment)

And 128/256 MB? This isn't a flash drive Razz We could use that, if there's a good price/reason. Wink
This is what i could find from a google search. also seen here. i realize i have no idea how large the screen is and that it only has 4 level grayscale. yeah... um. i know it doesn't meet the criteria on our list. but to be frank, when i tried looking for a 192x128 4 bit grayscale LCD, i got a ton of links to omnimaga and cemetech talking about some OTZ80 calculator. go figure. i tried.
Hahaha nemo, that's awesome. Thanks for trying. Smile That seems like it might help.

@Alberthro: Consider that the RAM address space is 16MB, I think we shouldn't skimp on flash. That Digikey data is very confusing, perhaps they're talking about the boot code.
nemo wrote:
This is what i could find from a google search. also seen here. i realize i have no idea how large the screen is and that it only has 4 level grayscale. yeah... um. i know it doesn't meet the criteria on our list. but to be frank, when i tried looking for a 192x128 4 bit grayscale LCD, i got a ton of links to omnimaga and cemetech talking about some OTZ80 calculator. go figure. i tried.


It depends. Can I trust a Chinese company? Wink
From some info, likely. If they go to the Shanghai Tech Expo, then they must be an official vendor.

And LMS195-F is interesting Smile EL backlight and such... but I still have no idea what grayscale they offer for this model.
lol, i was just looking for anything i could. personally, i think we should redo the screen resolution poll. we should find a large batch of possible screen models, and have several polls to lower it down to one. rather than saying "it has to be 192 x 128 4 bit grayscale backlit LCD", why don't we go out and find loads of LCD's going from 96x64 BW no-backlight to 320x240 8 bit grayscale backlit? that way we get a broad spectrum of models, and then have the community vote on them. the reason the processor voting was so easy is because there was a unanimous, pre-existing choice. in the LCD's case, we had no idea what was out there, we just assumed we would find what we were looking for.
nemo wrote:
0x5, i was just looking for anything i could. personally, i think we should redo the screen resolution poll. we should find a large batch of possible screen models, and have several polls to lower it down to one. rather than saying "it has to be 192 x 128 4 bit grayscale backlit LCD", why don't we go out and find loads of LCD's going from 96x64 BW no-backlight to 320x240 8 bit grayscale backlit? that way we get a broad spectrum of models, and then have the community vote on them. the reason the processor voting was so easy is because there was a unanimous, pre-existing choice. in the LCD's case, we had no idea what was out there, we just assumed we would find what we were looking for.
I absolutely agree with this; it's sorta what I was trying to suggest in the first place. Smile Nemo, any preferences what we include in such a poll?
I definitely agree that basing such a poll on that information would be a good idea. In the case of backlights you should also check the datasheet to see how much current it will require and (if possible, though this is rarely mentioned) whether the screen is usable with the backlight disabled. Power consumption is rather important on a battery-powered device! You should also check to see whether the LCD has a controller on board or not; those without are cheaper, but you'd need to find a way to drive them.
benryves wrote:
I definitely agree that basing such a poll on that information would be a good idea. In the case of backlights you should also check the datasheet to see how much current it will require and (if possible, though this is rarely mentioned) whether the screen is usable with the backlight disabled. Power consumption is rather important on a battery-powered device! You should also check to see whether the LCD has a controller on board or not; those without are cheaper, but you'd need to find a way to drive them.
Excellent points all around, Ben. Personally I'd be in favor of getting one with a built-in controller to save us some trouble in interfacing the LCD with our own controller, but I'd be willing to see what others have to say.
KermMartian wrote:
benryves wrote:
I definitely agree that basing such a poll on that information would be a good idea. In the case of backlights you should also check the datasheet to see how much current it will require and (if possible, though this is rarely mentioned) whether the screen is usable with the backlight disabled. Power consumption is rather important on a battery-powered device! You should also check to see whether the LCD has a controller on board or not; those without are cheaper, but you'd need to find a way to drive them.
Excellent points all around, Ben. Personally I'd be in favor of getting one with a built-in controller to save us some trouble in interfacing the LCD with our own controller, but I'd be willing to see what others have to say.


Having it built in is easier for us and probaly will have a smoother and highest-as-possible read and write cycles. A external controller may be cheaper though. it really depends on how expensive everything turns out to be(come). We really need to have low costs because there is going to be some money in actually producing a batch of these calcs. Sorry if I am getting ahead of matters but I think when choosing parts it's good to have cost vs quality in mind.

If we want to sell for about $90 then all the parts together should be about $60-70 and $10-20 production costs (really making PCB's is very expensive). Actaully I am hoping someone has a uncle or nephew in PCB making so we can get it done at a low price and greater reliability (and no troubles with sending it from country to country)

/offtopic, KermM, did you recieve my PM? Sorry for being impatient but I need to make sure you recieve it, once again, no pressure.
Quality vs. cost is absolutely important, and I also think we need to weigh saving a few dollars by having an external controller against our pain and suffering in choosing and especially coding software for such a controller.

Haha, PCB nepotism, I'd be happy to know if someone has PCB-making connections too. And yes, I got your PM, I'm mulling it over.
Kerm, i'm not really a hardware guy... i don't know what soldering is. when you say "PCB" i just kind of hope i'll get the context. so i don't really have many specific suggestions, but i think when choosing a screen these should be some main criterion:

- resolution
- grayscale level or BW
- backlight/no backlight

i think we should google and look around for anything that falls within 96 x 64 - 320 x 240 resolution, BW to 4-bit grayscale, no backlight to high power, always-on backlight, and everything in between. (excluding a 96x64 BW no-backlight.. cause that'd be pointless to the project.) of course, we would have to measure the power needed by each backlight, if it can be turned off. although i don't know how to measure the power needed, i'm sure someone else can.
nemo: PCB == printed circuit board. Nemo, it sounds like your Google-fu is strong; do you have any other suggestions in additions to the ones you mentioned earlier in the thread?
nemo wrote:
Kerm, i'm not really a hardware guy... i don't know what soldering is. when you say "PCB" i just kind of hope i'll get the context. so i don't really have many specific suggestions, but i think when choosing a screen these should be some main criterion:

- resolution
- grayscale level or BW
- backlight/no backlight

i think we should google and look around for anything that falls within 96 x 64 - 320 x 240 resolution, BW to 4-bit grayscale, no backlight to high power, always-on backlight, and everything in between. (excluding a 96x64 BW no-backlight.. cause that'd be pointless to the project.) of course, we would have to measure the power needed by each backlight, if it can be turned off. although i don't know how to measure the power needed, i'm sure someone else can.


PCB stands for Printed Circuit Board. Roughly said those are the green computer chips like so: http://www.bestdistilled.com.au/CompletedPrintedCircuitBoard.jpg

In a printed circuit board components can be placed closely together to save space and fit better in their final cases without having a tremendous bunch of wires hanging around. Heat is a side effect of PCB's because the great density means greater heat production...blablabla ( I noted I am getting off topic...)

I agree on sort of 'revoting/researching' the LCD's better, to fit our needs and financial capabilities better.
Now that we're doing more research it seems like other than initial case costs, the LCD is going to be the single largest money drain of the finished product. I wonder if that's the case for TI as well.
well.. besides thinking we should have a 128 x 64 screen after looking at Casio's webpage, or a 192 x 192 because there were an awful lot of pages for 192 x 192 LCD's. also, i'm suggesting no backlight. really. it's like throwing away money and power for something you won't need in school. i have to go, but when i'm back i'll have a list of potential 96 x 64 LCD's.
It's definitely a good idea for a revote if needed.
Backlight is something I like. It's in the Casios, so why not ours? Smile
If there is a solid, justifiable reason for not including them, then we'll remove that feature.

I think we should at least aim higher than 96x64, not repeat it again.
But as I've said, it's changeable in the future if needed. For now, let's try finding some parts for it. Wink
  
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