DIY USB Keyswitch Keychain

[Cixelyn]

I've lately been working on a functioning keyswitch keychain. I finally got around to making a thread on gh about it with some details 



The original concept was to make a tiny keyswitch keychain that fits entirely within the profile of a keycap but still acts as a fully functioning keyswitch. I'm still working on the firmware, but I've got it to the point where it can emulate a standard keyboard; it also has some entertaining alternate modes such as morse code input.

I searched for quite a while for a controller that would fit in the space constraints, since everyone's favorite atmega328 is just too large, making routing difficult. The trick was to find the smallest USB controller without going to some unfriendly, wafer-level package. I ended up using an SiLabs 8051 chip with a 3x3mm QFN package. Honestly, it's quite nice; hopefully more people use it in the future for tiny builds.

There are some 0.1" headers exposed -- the plan is to allow daisy-chaining of multiple keychains via i2c/smbus so that wiring up a macropad/numpad is super simple. If anyone knows of any similar projects, please let me know so I can make the protocols compatible. Otherwise I'll try to come up with something simple and reusable.

Anyways, last time I posted about this, a ton of people expressed interest in buying one, so I'm hoping to run a small groupbuy through the friendly folks at crowdsupply. I still have a ton of work to do though -- planning on releasing the firmware+schematics as open-source once I finish up this next revision. I'm also hoping to integrate an rgb led on the pcb, as well as make it (somehow) matias compatible.

Let me know if you guys have any questions, happy to share notes! Also, does anyone know where to get Matias keycaps in singles?

[suicidal_orange]

Is that hand soldered 0.1mm?

I know I'm being lazy but how much memory does this have?  The only use I can think of for a functional keychain would be to type in a crazy secure password.  I guess if you strip out the morse code there would be enough...

That said most fun things in life aren't very practical and it's impressive that you managed this - good work!

[Data]

That...  What... How did you...  I can't even.

[Sifo]

lol very nice.

[Cixelyn]

Is that hand soldered 0.1mm?

Haha yeah, I did all the original prototypes by hand, but I've since wised up and just gotten my board house to assemble them for me. It's not quite 0.1mm, everything there is 0.5mm pitch. And all the passives are 0402, not yet ready to commit to the effort (and price) of 0201.

I know I'm being lazy but how much memory does this have?  The only use I can think of for a functional keychain would be to type in a crazy secure password.  I guess if you strip out the morse code there would be enough...

16KB memory for code. My current code (including USB stack) is only using about 6KB so I still got a fair amount of space.

That said most fun things in life aren't very practical and it's impressive that you managed this - good work!

Haha thanks so much! I've seen a lot of single key keyboard builds around here but they all use either a teensy (which makes it massive) or an attiny85 (which makes it kind of unreliable as it's bit-banged USB). I really just wanted to make a proper one, and it seems like people really seem to like the concept.

lol very nice.

That...  What... How did you...  I can't even.

Thanks so much for the support guys!

[xtrafrood]

Holy guacamole!

[QuincyJones]

really nice! and i love that kawaii key!

[SBJ]

I've lately been working on a functioning keyswitch keychain. I finally got around to making a thread on gh about it with some details 

(Attachment Link)

The original concept was to make a tiny keyswitch keychain that fits entirely within the profile of a keycap but still acts as a fully functioning keyswitch. I'm still working on the firmware, but I've got it to the point where it can emulate a standard keyboard; it also has some entertaining alternate modes such as morse code input.

I searched for quite a while for a controller that would fit in the space constraints, since everyone's favorite atmega328 is just too large, making routing difficult. The trick was to find the smallest USB controller without going to some unfriendly, wafer-level package. I ended up using an SiLabs 8051 chip with a 3x3mm QFN package. Honestly, it's quite nice; hopefully more people use it in the future for tiny builds.

There are some 0.1" headers exposed -- the plan is to allow daisy-chaining of multiple keychains via i2c/smbus so that wiring up a macropad/numpad is super simple. If anyone knows of any similar projects, please let me know so I can make the protocols compatible. Otherwise I'll try to come up with something simple and reusable.

Anyways, last time I posted about this, a ton of people expressed interest in buying one, so I'm hoping to run a small groupbuy through the friendly folks at crowdsupply. I still have a ton of work to do though -- planning on releasing the firmware+schematics as open-source once I finish up this next revision. I'm also hoping to integrate an rgb led on the pcb, as well as make it (somehow) matias compatible.

Let me know if you guys have any questions, happy to share notes! Also, does anyone know where to get Matias keycaps in singles?

That is amazing. Well done!
So could you in theory use it as some sort of password access device, where you'd hook it up to your pc, press the button and it would unlock something? (like a hidden drive)

[Cixelyn]

That is amazing. Well done!
So could you in theory use it as some sort of password access device, where you'd hook it up to your pc, press the button and it would unlock something? (like a hidden drive)

Yeah that could be possible. Might also be able to use it as a U2F token for two-factor authentication as long as you're ok with the hardware not being tamper-resistant.

[QuincyJones]

That is amazing. Well done!
So could you in theory use it as some sort of password access device, where you'd hook it up to your pc, press the button and it would unlock something? (like a hidden drive)

Yeah that could be possible. Might also be able to use it as a U2F token for two-factor authentication as long as you're ok with the hardware not being tamper-resistant.

The problem with having something like this as a password device is if you get arrested because you're in the wrong place at the wrong time, or because you're just black/indian/ethnic minority, then the police will normally go through and mess about with this and you may be asked a lot of questions or get the "OMG UR TERRORIST U HAVE DETONATOR - OFF 2 JAIL DON'T PASS GO" type crap.

[Cixelyn]

Maybe? Plenty of people have USB thumb drives and other techy things on their keychains these days, I don't think it'll really pose any problem.

[CPTBadAss]

Ha I love projects that are just done for funsies. It'd be cool to have the switch activate an LED and be a little flashlight as well. Not keyboard related I know but might be functional.

[mrhead]

Ha I love projects that are just done for funsies. It'd be cool to have the switch activate an LED and be a little flashlight as well. Not keyboard related I know but might be functional.

This. You've given me a purpose.

[Cixelyn]

Ha I love projects that are just done for funsies. It'd be cool to have the switch activate an LED and be a little flashlight as well. Not keyboard related I know but might be functional.

I'm currently trying to fit a universal RGB LED that should work with any switch footprint. I guess you could connect up the key to a USB battery pack and use it as a flashlight or ravelight.

[MacGruber117]

I want this so bad! Will there be a small case, or has it been determined that it will be durable enough on its own?

[Cixelyn]

I want this so bad! Will there be a small case, or has it been determined that it will be durable enough on its own?

I've had a copy on my keychain for a few weeks now and haven't really seen any structural damage or issues. As someone said in the last thread, the bare PCB has a fairly geek-chic sort of look which is kind of appealing. I'll definitely provide files for people to 3D print their own cases if they want... not sure if an actual case option will be provided in the group buy.

Anyways, as a teaser, here's a small update which I put on twitter but forgot to post here:



Currently waiting for the new rev2 of the boards to get back. I've made a large number of layout changes for structural integrity, esd resistance, and aesthetics. Will be in a much better state to launch the project once I confirm everything works.

[Hydra04]

Interest check: +1.

[xtrafrood]

I want this so bad! Will there be a small case, or has it been determined that it will be durable enough on its own?

I've had a copy on my keychain for a few weeks now and haven't really seen any structural damage or issues. As someone said in the last thread, the bare PCB has a fairly geek-chic sort of look which is kind of appealing. I'll definitely provide files for people to 3D print their own cases if they want... not sure if an actual case option will be provided in the group buy.

Anyways, as a teaser, here's a small update which I put on twitter but forgot to post here:

(Attachment Link)

Currently waiting for the new rev2 of the boards to get back. I've made a large number of layout changes for structural integrity, esd resistance, and aesthetics. Will be in a much better state to launch the project once I confirm everything works.

Retweeted!

[Arokai]

is this still in progress? i'm really looking forward to this!

[mrhead]

Just checking to see if anything new has developed.  My project went absolutely nowhere.  By that, I mean that I didn't do anything.