Author Topic: Hotswap BLE Compact Pocket Sized Keyboard  (Read 3652 times)

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Offline pabile

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Hotswap BLE Compact Pocket Sized Keyboard
« on: Thu, 09 January 2020, 02:28:22 »
ola GH! i am trying to design a keyboard that is: 1) compact and small enough that a case can be printed using common 3d printers, i.e. within 220x220 sqr mm; b) bluetooth functionality; c) low cost / cheap; d) hotswap-able switches.

so far, i have this design:


PCB/plates length and width is within my requirements: ~215 x 79mm

...and here is where i wanted your thoughts/inputs...

a) thinnest battery i found online is 5mm thick and is only 500mA iirc. I can go bigger but will use up large area of the bottom of the board and will make this keyboard thick. How would you approach this? Settle with small capacity battery? How long do you think a 500mA will last for this setup?



b) I am also thinking of having an option to use mx switch instead of rotary encoder... or blank this area completely?

c) Micro controller is better placed on the right, correct? Easy access to on board battery port/jack.

The PCB is currently designed for 32u4 bluefruit feather https://www.adafruit.com/product/2829 but will also accept promicro. Battery is intended to be soldered at the bottom of the PCB (top left).

233270-2

TIA

Offline piit79

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Re: Hotswap BLE Compact Pocket Sized Keyboard
« Reply #1 on: Thu, 09 January 2020, 03:19:13 »
Nice project! If you wanted a really compact board you could use Kailh Choc switches and use smaller switch pitch (like the Pancake).

I have no estimate how long could the 500 mAh last but I would definitely go bigger - 1000 mAh at least. Thin is nice, but I prefer function over form ;) I got a 2000 mAh battery for my Pancake (also with Bluefruit Feather). I assume the 500 mAh battery is pretty small so as a workaround you could wire two in parallel. You could however possibly run into problems with unbalanced charging (or not, when in parallel? Not entirely sure).

Offline pabile

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Re: Hotswap BLE Compact Pocket Sized Keyboard
« Reply #2 on: Thu, 09 January 2020, 03:31:44 »
...

thanks, piit.

choc switches are currently out of my range but is definitely considering those. however, i think the battery thickness will still be the problem. i'll do some reading on parallel lipo batteries. are unbalance charging really a thing for these? i have not seem a Pancake. i'll check those as well. thanks again :)

Offline nevin

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Re: Hotswap BLE Compact Pocket Sized Keyboard
« Reply #3 on: Thu, 09 January 2020, 05:00:23 »
yes, LiPo charging is very different than other types of battery chemistries. do not use more than one cell unless you plan on using a balance charger (charges & monitors each cell individually). use a larger single cell. there are tons of battery manufacturers, you could search by size or capacity.

did a quick search.... here's a site with a ton under 3mm
https://www.lipolbattery.com/Ultra-Thin-LiPo-Battery.html
even if you don't buy from them, it will give you some idea of what's out there.
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Offline pabile

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Re: Hotswap BLE Compact Pocket Sized Keyboard
« Reply #4 on: Thu, 09 January 2020, 06:20:21 »
yes, LiPo charging is very different than other types of battery chemistries. do not use more than one cell unless you plan on using a balance charger (charges & monitors each cell individually). use a larger single cell. there are tons of battery manufacturers, you could search by size or capacity.

did a quick search.... here's a site with a ton under 3mm
https://www.lipolbattery.com/Ultra-Thin-LiPo-Battery.html
even if you don't buy from them, it will give you some idea of what's out there.

thanks for the inputs, nevin.
those sure are very thin batteries. nice to know that very thin ones exist. it may take some time and/or money but i'll keep an eye on these. thanks again :)

Offline equalunique

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Re: Hotswap BLE Compact Pocket Sized Keyboard
« Reply #5 on: Thu, 09 January 2020, 11:44:16 »
Amazing work! Glad to see Adafruit's bluetooth board getting more love.

Looks like a near-perfect board for me. Only thing I wish it could support is 2x2u space.

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Offline pabile

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Re: Hotswap BLE Compact Pocket Sized Keyboard
« Reply #6 on: Thu, 09 January 2020, 19:04:11 »
sweet! glad you liked it, equalunique!

2x2u seems pretty peculiar to me. I might take a look at that sometime.

Offline pabile

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Re: Hotswap BLE Compact Pocket Sized Keyboard
« Reply #7 on: Sun, 19 April 2020, 04:28:30 »
so... there have been a small detour and things had me a macropad produced instead. good thing i did this before sending my OP to production. i am errors and several things that should have been considered.

here's a look at the 18-key:

240210-0
240216-1
hotswap, encoder/switch option on the right, promicro or bluefruit for microcontroller.

240212-2

240214-3

more info of this build from my blog https://pabileonline.blogspot.com/search/label/p18

...still needs bluefruit to fully test through.

Offline pabile

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Re: Hotswap BLE Compact Pocket Sized Keyboard
« Reply #8 on: Sat, 18 July 2020, 11:08:45 »
i am currently typing on this version. works well except for net issues with rgb and encoders. it is quite low, as i wanted it, but will definitely be bulkier if i choose to have it ble'd and a battery at the back.

247471-0

247469-1

pcb specs/compatibility: promicro x bluefruit LE compatible; ws1812 leds (untested/non-cascade-able); kailh hotswap sockets

i am thinking of redesigning the whole thing to keep my target, low and compact (choc switches aside), and the only way i see it is that it will look like the discipline, components on top. back to the drawing board...please share your thoughts. i need ideas.

Offline nevin

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Re: Hotswap BLE Compact Pocket Sized Keyboard
« Reply #9 on: Mon, 27 July 2020, 11:31:08 »
Take a look at keeb.io. a bunch of their early revisions used separate controllers like this and mounted under the pcb with minimal added height. Actually, pretty neat & tricky pcb work.
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Offline pabile

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Re: Hotswap BLE Compact Pocket Sized Keyboard
« Reply #10 on: Mon, 27 July 2020, 17:37:55 »
thanks, nevin. i wish you were my neighbor or at least live within the country. you have all my answers  :thumb:
take care!

Offline nevin

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Re: Hotswap BLE Compact Pocket Sized Keyboard
« Reply #11 on: Mon, 27 July 2020, 17:47:55 »
no prob.

will definitely pickup one of your 1st split boards when you get to that point. keep up the good work!

also, check out reverse_bias's mitosis
https://www.reddit.com/r/MechanicalKeyboards/comments/66588f/wireless_split_qmk_mitosis/
« Last Edit: Mon, 27 July 2020, 18:00:28 by nevin »
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Online coarse

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Re: Hotswap BLE Compact Pocket Sized Keyboard
« Reply #12 on: Mon, 27 July 2020, 23:08:39 »
if you wanna keep it compact, you should go and use a bluetooth module like the nrf52840.

if you dont wanna deal with lipo, you could use coin cell batteries like what the mitosis does. it adds height to the pcb but at least not as much compared to using a lipo cell. you also dont need to add a charging circuit for your board as well. if you want to, you could also remove the usb connector which should also remove the need for a voltage regulator and a circuit for switching between usb and cell power.

Offline pabile

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Re: Hotswap BLE Compact Pocket Sized Keyboard
« Reply #13 on: Tue, 28 July 2020, 05:05:40 »
if you wanna keep it compact, you should go and use a bluetooth module like the nrf52840.

if you dont wanna deal with lipo, you could use coin cell batteries like what the mitosis does. it adds height to the pcb but at least not as much compared to using a lipo cell. you also dont need to add a charging circuit for your board as well. if you want to, you could also remove the usb connector which should also remove the need for a voltage regulator and a circuit for switching between usb and cell power.

thanks coarse. these are out of my capabilities but will definitely look into it. tc

Offline AGmurdercore

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Re: Hotswap BLE Compact Pocket Sized Keyboard
« Reply #14 on: Tue, 28 July 2020, 05:40:12 »
Nice build! What is the maximum matrix size with the controller that you are using? I am planing on building a 75% wireless board in the future and I am wondering what controller should I choose for that.
What the hell am I even doing

Offline pabile

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Re: Hotswap BLE Compact Pocket Sized Keyboard
« Reply #15 on: Tue, 28 July 2020, 08:01:58 »
Nice build! What is the maximum matrix size with the controller that you are using? I am planing on building a 75% wireless board in the future and I am wondering what controller should I choose for that.

[removed]

edit: i think i am still a little disoriented with whats going on around... please see nevin's comment instead. as always, thank you, nevin.
« Last Edit: Tue, 28 July 2020, 08:47:50 by pabile »

Offline nevin

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Re: Hotswap BLE Compact Pocket Sized Keyboard
« Reply #16 on: Tue, 28 July 2020, 08:25:38 »
Adafruit Feather 32u4 Bluefruit LE has 17 available i/o pins. so for a 75% you'd probably have to add an i/o expander or something (for 87 keys)
Though if you get really creative with your key matrix, say, 8x9 it can support up to 72 keys, converting that key matrix into a usable layout may be a bit tricky if you don't watch what you're doing. (it's not as straight forward as using the physical placement of the keys as your key matrix. (6x17 for a TKL)
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Online coarse

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Re: Hotswap BLE Compact Pocket Sized Keyboard
« Reply #17 on: Tue, 28 July 2020, 12:03:00 »
thanks coarse. these are out of my capabilities but will definitely look into it. tc

in that case you might want to try and get your hands on an nrfmicro instead. https://github.com/joric/nrfmicro/wiki
much lower height compared to adafruit's boards but you will have to add your own battery connectors. if youre already familiar with making boards using a pro micro, then i think an nrfmicro would be a perfect.

Nice build! What is the maximum matrix size with the controller that you are using? I am planing on building a 75% wireless board in the future and I am wondering what controller should I choose for that.

you would need a controller with at least 18 pins available, but a controller with 21/22 pins is recommended for a 75%. you could use the nrfmicro since it has 19 pins, but making the pcb would be a bit difficult with just 19 pins.


Offline pabile

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Re: Hotswap BLE Compact Pocket Sized Keyboard
« Reply #18 on: Tue, 28 July 2020, 17:42:18 »
wow! that's something, coarse. i am about to read the whole docs and will surely grab/build one of these! thanks!

Online coarse

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Re: Hotswap BLE Compact Pocket Sized Keyboard
« Reply #19 on: Tue, 28 July 2020, 19:56:34 »
if you live in the same country as i do, you can checkout packetworx if youre near pasig. https://www.packetworx.com/Iot-technology-hub/ you could use their tools to easily build the nrfmicro.

they have a makerspace meant for electronics, so they have pick and place machines, reflow ovens, soldering tools, and even cnc equipment. im not sure if theyre open now, though.

Offline pabile

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Re: Hotswap BLE Compact Pocket Sized Keyboard
« Reply #20 on: Tue, 28 July 2020, 22:53:50 »
if you live in the same country as i do, you can checkout packetworx if youre near pasig. https://www.packetworx.com/Iot-technology-hub/ you could use their tools to easily build the nrfmicro.

they have a makerspace meant for electronics, so they have pick and place machines, reflow ovens, soldering tools, and even cnc equipment. im not sure if theyre open now, though.

waah! sino ka?
this is awesome information, coarse! i'll do some reading first. we'll see where it'll take me.

Offline AGmurdercore

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Re: Hotswap BLE Compact Pocket Sized Keyboard
« Reply #21 on: Wed, 29 July 2020, 01:47:25 »
thanks coarse. these are out of my capabilities but will definitely look into it. tc

in that case you might want to try and get your hands on an nrfmicro instead. https://github.com/joric/nrfmicro/wiki
much lower height compared to adafruit's boards but you will have to add your own battery connectors. if youre already familiar with making boards using a pro micro, then i think an nrfmicro would be a perfect.

Nice build! What is the maximum matrix size with the controller that you are using? I am planing on building a 75% wireless board in the future and I am wondering what controller should I choose for that.

you would need a controller with at least 18 pins available, but a controller with 21/22 pins is recommended for a 75%. you could use the nrfmicro since it has 19 pins, but making the pcb would be a bit difficult with just 19 pins.
Thank you guys (nevin as well!). I will probably keep on looking to find the best controller for my needs as this will be a little too small it seems. I am also intending to go the cheap way and spare me some money from creating a PCB by hand wiring the whole thing.
What the hell am I even doing

Online coarse

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Re: Hotswap BLE Compact Pocket Sized Keyboard
« Reply #22 on: Wed, 29 July 2020, 06:54:13 »
Thank you guys (nevin as well!). I will probably keep on looking to find the best controller for my needs as this will be a little too small it seems. I am also intending to go the cheap way and spare me some money from creating a PCB by hand wiring the whole thing.

i was also checking out similar controller boards and found out about the nice!nano. uses the same chip as the nrfmicro but it has 21 pins easily available. definitely usable for your build  ;)

Offline AGmurdercore

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Re: Hotswap BLE Compact Pocket Sized Keyboard
« Reply #23 on: Wed, 29 July 2020, 08:25:34 »
Thank you guys (nevin as well!). I will probably keep on looking to find the best controller for my needs as this will be a little too small it seems. I am also intending to go the cheap way and spare me some money from creating a PCB by hand wiring the whole thing.

i was also checking out similar controller boards and found out about the nice!nano. uses the same chip as the nrfmicro but it has 21 pins easily available. definitely usable for your build  ;)
That sounds amazing, I will check it out. Thank you!
What the hell am I even doing

Online coarse

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Re: Hotswap BLE Compact Pocket Sized Keyboard
« Reply #24 on: Wed, 29 July 2020, 09:01:11 »
the maker of the bluemicro controllers also messaged me and told me he has a shop for selling pre-assembled controllers. if anyone wants to try them out, you can check their store here

Offline nevin

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Re: Hotswap BLE Compact Pocket Sized Keyboard
« Reply #25 on: Wed, 29 July 2020, 10:32:47 »
nice find @course will definitely check them out.

for larger (wired) boards, the Teensy++ 2.0 is one of the most common with plenty of i/o pins

for handwired boards, the Postage Board Mini is a godsend (not wireless) but made for handwired boards (25 i/o pins). the board attaches to the bottom of 3 switches, so no need to find a place to mount the controller.
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Offline pabile

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Re: Hotswap BLE Compact Pocket Sized Keyboard
« Reply #26 on: Thu, 30 July 2020, 11:14:00 »
the maker of the bluemicro controllers also messaged me and told me he has a shop for selling pre-assembled controllers. if anyone wants to try them out, you can check their store here

cool stuff! i find it quite pricey though.
i read most of the nrfmicro docs and that controller looks pretty amazing. especially the programming kit.. always wanted to learn those.