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geekhack Community => Keyboards => Topic started by: Greywolf on Tue, 10 December 2019, 16:55:41

Title: Recommended microcontroller for 100+ keys? Looking at Teensy models.
Post by: Greywolf on Tue, 10 December 2019, 16:55:41

Greetings and I apologise profusely if this is a repeated topic, but the search function does not seem to narrow down my query very well.

In order to keep things (relatively) simple, I'm looking into using a Teensy for my DIY board.  I have > 100 keys (105) so 20 pins of matrix are insufficient, therefore a Teensy 2.0 won't work, so I'm looking at the Teensy 2++.

Question I have is:  Should I just upgrade to one of the Teensy 3 models, or is a 2++ sufficiently stable, or should I be looking at a different uC altogether?  Pros/Cons if you have them to offer.

Shade and Sweet Water,
--*greywolf;

Title: Re: Recommended microcontroller for 100+ keys? Looking at Teensy models.
Post by: suicidal_orange on Tue, 10 December 2019, 17:19:20

The 2.0++ is supported in all firmwares and is the go-to for big boards, I've been using one in my reincarnated Ducky for five years with no problem so I think it's safe to call it stable.  Just don't buy a fake or strange things may happen (https://geekhack.org/index.php?topic=102719.0)!

Title: Re: Recommended microcontroller for 100+ keys? Looking at Teensy models.
Post by: Findecanor on Tue, 10 December 2019, 17:28:06

The Teensy 2.0 has 25 pins. Do you really need 5 LEDs?

The Teensy++ 2.0 is enough. Of the Teensy 3 series, only Teensy 3.2 and Teensy LC have firmware support. The Teensy 3.2 has 24 actual pins + 10 SMT pads.

Because only one column (or row) is strobed at a time, you could also use a "shift register" or a "decoder" chip. Turn a 22×6 matrix into 11×12 and you would need only 11+4 = 15 microcontroller pins if you'd use a 4-to-16 decoder.

Title: Re: Recommended microcontroller for 100+ keys? Looking at Teensy models.
Post by: gipetto on Tue, 10 December 2019, 17:34:19

I have a teensy 2.0 driving a 110 key full size board and 3 indicator leds, although scroll lock doesn't work because of a bug. I could have even dedicated the last pin to a backlight. it's fine. learn how to route. I didn't use a single via on my pcb traces because i used through hole diodes.

Title: Re: Recommended microcontroller for 100+ keys? Looking at Teensy models.
Post by: Tom_Kazansky on Wed, 11 December 2019, 00:53:12

how about QMK Proton-C (http://"https://olkb.com/parts/qmk-proton-c") ? there are 23 pins. You can route with 11x10 (21 pins, 110 keys total) and have 2 pins for indicator/backlight led.

Title: Re: Recommended microcontroller for 100+ keys? Looking at Teensy models.
Post by: Greywolf on Wed, 11 December 2019, 03:07:29

DANGER! DANGER! RABBITHOLE!  ABORT!  ABORT!

Good to know about the Proton!  Backlight LED could be sweet, too, once I figure that out.

I've ordered a Teensy 2++ but will order a Proton as well and...well, let's see what happens.  The USB-C is a fair draw for me.

[I don't even have the PCB plotted yet.]