Can we design the teensy alternative for keyboards?

[matt3o]

asked for a quotation for final design... I'll keep you posted

[matt3o]

okay, it seems the manufacturer is pushing really hard to make the boards on 5x4 panels. I don't like it but they say for large quantities it's the best (and possibly only) way... I'm not sure how they can do panels with our shape, but anyway we'll see. I should get a quote today.

[pomk]

Yeah, pnp machines usually take just one size of pcbs, so some form of panelization is necessary. The castellated edges are a nice place for some v-scoring and as long as some support is retained throughout the board it should work out fine.

[vvp]

Panels are the normal way to do it.

When I was ordering I was told that v-scorring discs are in sizes like a small or normal size CD disc. They can do only long straight cuts. And the cuts are still connected in the middle. One just breaks them away there when it is all finished. If the middle part also contains Cu-plated holes (as is the Elf board case) then I can imagine that breaking the PCB along v-score can rip some Cu plating from the castellated edge. Did you already break some PCBs with castellated v-scored edges? Just want to know whether v-scoring is really safe for them.

The side with the USB connector will definitely need milling since it is not straight.

[matt3o]

I got a preliminary quote, it is just a tad more than I wished. Basically to have decent pricing I would have to produce at least 500 possibly 1000, which is quite something.

I guess with a 200-ish batch they would cost around €15 each.

[derzemel]

I got a preliminary quote, it is just a tad more than I wished. Basically to have decent pricing I would have to produce at least 500 possibly 1000, which is quite something.

I guess with a 200-ish batch they would cost around €15 each.

can this teensy 2.0 alternative be used for other things than keyboards?
It could gather interest form other types of DYI people too, not only keyboards fans and the way it is build, with the USB connection on the side, could proove usefull to many people.
if yes, then you have a business on your hands

[matt3o]

yes, of course can be used for anything.

[derzemel]

yes, of course can be used for anything.

Then, a heads-up on the electronics forums could gather even more interest

[pomk]

The price feels a bit excessive. I'll get a quote from a place I use for my projects just to see if they are trying to rip you off.

[pomk]

I got an initial quote of under 500 usd plus the price of components for 200 boards.

[matt3o]

components is about $1400. if you add tax and shipping the cost for the end user is around €12-15

[pomk]

Yeah, I checked that as well. It looks like we chose an awfully expensive IC. Components at around 1300 USD, so PCB + components + manufacture + shipping to somewhere is about 10 USD per piece. VAT adds some 20% and so on. We could remove the reset button and save 1 USD per piece

[matt3o]

one button is to reset and one is to start the bootloader right?

the reset is more useful for development outside the keyboard scope I guess. not strictly needed if you already use a TMK firmware for example.

[pomk]

one button is to reset and one is to start the bootloader right?

the reset is more useful for development outside the keyboard scope I guess. not strictly needed if you already use a TMK firmware for example.

The bootloader is button is necessary in case the firmware you load is messed up. You can always reset the board by yanking the cable.

[Wodan]

If you hand-wire a keyboard, can't we safely assume you can hand-short two pads?

[pomk]

Sure. It's just annoying to keep the pads shorted while you plug a cable in. The board can be configured so that there is a timeout for the bootloader regardless if the bl button is pressed, so it would have to be shorted only once. In this configuration one would enter the bootloader by yanking the cable and then within the timeout send first command to the bootloader in order to force it to stay on. Still I think that the buttons are a more elegant solution, and true hand-wiring specialists can just buy the chip by itself at 3,5 USD and wire to its pins directly.

[matt3o]

The bootloader is button is necessary in case the firmware you load is messed up. You can always reset the board by yanking the cable.

of course we need the bootloader, what I'm saying is that I don't see the reset to be terribly needed. I mean you can just unplug the cable, but probably I'm missing something.

[Matt_]

You mention 12-15€ for 200 boards, and a decent pricing for 1000 of them — what would be the price at that quantity?

A Teensy 2.0 costs $16, more for Europeans, and has lesser capabilities (fewer pins, less powerful). A Pro Micro is a good cheap alternative but it's even more limited. With that in mind, 12-15€ should be acceptable for enthusiast builders, especially if it's easy to program/build a firmware. Not ideal "oh my god I'll get ten of them", but acceptable. Can't you run an interest check on DT and GH (perhaps on reddit too, I don't know if there are a lot of builders there) to see how many you could expect to sell?

[matt3o]

yeah it's not bad, it's totally reasonable for an enthusiast but would have been nice to stay lower than 10. I believe that at 1000 the price is at least 30-40% lower.

[vvp]

The board can be configured so that there is a timeout for the bootloader regardless if the bl button is pressed, so it would have to be shorted only once.

Won't this force windows to search for a driver for the bootloader at the moment the keyboard si connected?

[pomk]

yes, for the (user settable) timeout duration anyway.

[matt3o]

I got the final quote and I can confirm my initial estimate. About €15 all included per piece. To go under €10 I would need to make 1000, which is insane.

Unfortunately at this stage I can't do a pre-order because there's a slight chance that they won't actually be working, so the initial investment would be all on me anyway.

[Matt_]

Unfortunately at this stage I can't do a pre-order because there's a slight chance that they won't actually be working

Why not make a last small batch to check that everything works, before committing to larger quantities? Too costly?

[MrBishop]

following with great interest. i'd love to replace teensy's with these in my hand wired boards. would simplify alot of stuff for me. well done Matt3o you never disappoint

[matt3o]

Why not make a last small batch to check that everything works, before committing to larger quantities? Too costly?

a small run would be another $500 bringing the dev investment to $1000, I know it should be done, but the changes from the original design are small and the risk very low... so...

following with great interest. i'd love to replace teensy's with these in my hand wired boards. would simplify alot of stuff for me. well done Matt3o you never disappoint

thank you, man I'm not worthy

[matt3o]

before placing the order I was reviewing the board. I noticed that if you place the board between the PCB and the plate the buttons are really close to the plate and if the plate flexes I feel like the buttons could get pressed. Any comment?

[pomk]

The switch cutouts are only for attaching it to the bottom side. I guess you could attach it on the top side close to the spacebar or something. It would need holes for accessing the buttons anyway though?

[matt3o]

you would need to make two pretty big holes (not just like 1mm for accessing them but a hole able to fit the whole button), or maybe one rectangular hole that takes both.

[pomk]

I dont have calipers at hand, but with a basic ruler I'd say that the 1-2mm holes should suffice with 1,5mm plates. A rectangular hole for both switches should work just as well. I'll check the techical drawing.

[pomk]

The button head is 1,5 mm in diameter, so a 2 mm hole would be good. The button casing is 1,2 mm tall, so combined with the 1,6 mm PCB the total height without the button heads is 2,8 mm. From plate top to PCB the height for MX style switches should be 5 mm, so the plate could be even 2,2 mm tall before causing clearance problems if we assume all tolerances to be zero. In conclusion a basic 1,5 mm top plate should cause no issues with just holes for the button heads.

If the plate is laser cut, you could even scribe the functions around the holes.