So, apparently TI did something nice by accident. It just so happens that the nspire has 20 data pins in its keypad connector. Right now, they are occupied with detecting keys, but I think that could easily be reduced, leaving lots of room for modifications!

The easiest method of reduction, of course, being a PS/2 keyboard slot. that only takes 1 data pin, leaving 19 more. (And think of how much easier it will be to type on!)

Now, it's a given that those pins are hard to reach by any standard with a keypad in, which limits their usefulness, so I was thinking of this: Instead of using the connectors with a current keypad, what about modifying it so that it has these features built in? It could include various things, such as:

PS/2 Connector (obviously Razz)
SD card slot
84+ link port
Audio port
Joystick port (maybe with an included ADC for the analog)
Plug-in Leads (like your voltmeter's)
And, of course, .1" pin headers to the surface for the rest, or including above

I was thinking of these replacing the keypad front face. That way your calculator pad isn't simply empty: It has the feel of another keypad option!

Also: The CAS touch's pad isn't different from the regular nspire's in any way, it's just got a different shaped, completely unnecessary lip on the top. remove the lip and they're interchangeable.

I am also aware of the fact that the OS will not recognize a PS/2 keypad without modification (like ndless can achieve) Wink
That sounds like an awesome idea!
The biggest problem I forsee at this point is a good way to make the front of the pad. my soldering skill is sufficient to solder to the connector, and I can just trim the rest of the PCB off, but I don't really have any decent materials for it, except maybe my half-finished vacuum-forming table. (The table works, but I have no heating element or plastic clamps)
hhmm. Frankenstien an Nsipre keypad? reroute keys to use a PS2 port, then use the other features from inside the keypad. So just modify the keypad to do what you want.
ehh, rerouting the keys through the PS/2 port means rerouting them through a keyboard chip. Also, I would have to disconnect their current connections. Also, That PCB being gone was where I planned to get room for the features from Razz I am thinking, though, that I could gut a pad and remove keys and pcb, then make a vacuum-formed mold that clips over the top (or is glued) which houses all the connectors.

I'm not afraid of ruining keypads since they're so cheap. $10 isn't bad for making an awesome keypad. Very Happy
Sounds good, I would almost pay you to make me one. haha
only almost? Razz I think I would make them for a price, depending on how much I hate doing the first. Wink Any features you think it needs? I'm leaning towards not putting in the ADC joystick though, considering the size of those connectors. I could easily put in an Atari-compatible one though, they're really easy.
I meant almost pay you, meaning I would almost pay money for it, not that I wanted one for free. A mouse, would be rather nice. 1 more PS2 port of 1 pin. Even if it had like a laptop internal mouse type thing.
Aes_Sedia5 wrote:
I meant almost pay you, meaning I would almost pay money for it, not that I wanted one for free. A mouse, would be rather nice. 1 more PS2 port of 1 pin. Even if it had like a laptop internal mouse type thing.
The literal PS/2 spec requires two data pins (data and clock), a 5V power supply of a few dozen mA at least, and a common ground. Is that what you mean?
Yeah, ben corrected me on that in IRC (I missed it on the pinout somehow Razz), but there are power pins available on said connector. They're 3.3v though, so it'll need a level shifter for any data, and some way of getting 5v (I believe there's a 5V line in the dock connector, I'll have to check again)

Where did you get the power from for your 'Ultimate Calculator' series?
AFAIK, the pins on the bottom are only 3.3v. But I can be wrong.
Wouldn't it be better to use the pins on the dock connector? I'm sure there will be some gpio pins there, and is more easy to use than the ones of the keypad.
But the dock connector is harder to make a good connector for. I've tried. The keypads are actually buyable for a reasonable price. Plus, there's fewer pins on the dock connector.

There is the advantage of not excluding any calcs though, except for the CX-M or whatever it was that has no dock.
*three-year necrobump* I wasn't actually sure where to post this, but I recently bought a set of 24 TI-Nspire keypads for about $5, so I sacrificed one to science. Here's what's inside the Nspire keypad: from left to right, the front cover with the larger keys, the membrane with the small alphabetic and secondary math keys, the mainboard, and the back cover. Note the metal plate that the latching mechanism latches into to hold the keypad securely. The PCB in the keypad appears to have four test points, three of which are labelled SP1-SP3 and one of which is unlabelled, but since they don't appear to connect electrically with any traces, I believe they're used for aligning the keypad PCB in some test jig. The edge connector has an intriguing number of unused pins, as willrandship mentioned. I also found it interesting that the directional pad actually has contacts and corresponding plastic pins for eight directions, rather than simply reading the combination of two cardinal directions as a diagonal.

I also posted a real topic about this and about what I should do with 24 Nspire keypads.

Click for full-sized image
That's amazing. I'll keep my longer responses in the other topic.
  
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