[Question] Which controller should I use for a custom TKL

[help-14]

I'm new to kicad and PCB design, working on my first custom TKL keyboard. The problem is I don't know which controller should I use. The TKl have 6 rows and 17 columns, plus 3 pin for RGB led so I need at least 26 pins, ATMEGA32U4 is only have 20 digital pins

[suicidal_orange]

If you're making your own PCB the 32u4 has 26 I/O pins as stated on the Atmel webpage, the analogue inputs and pins with special features can be used as digital ones

[help-14]

Oh, thank for your answer. When googling ATMEGA32u4 I saw it said 20 digital pins, didn't know other pins can be use as digital too 

[Findecanor]

You could optimize the number of pins needed by making the logical matrix closer to a square.
A typical ANSI TKL has 87 keys. 9×10 or 8×11 would need 19 pins.
The downside is of course that it would make routing and programming a little bit more difficult.

[help-14]

Another question, can I use this to control the keyboard? I mean I'll use this design controller for GMK firmware.

[suicidal_orange]

I don't know what all that extra stuff is but Port B.1, 2 and 3 are three of the special pins you need for I/O and they're being used to connect to another chip, so you can't use this schematic.  Unless you just mean the USB part?  That should work...

[help-14]

Do you happed to have a schematic that I can use

[suicidal_orange]

The GH60 doesn't have anything extra, but it does have expansion headers at the top, bottom and on the left side.

[help-14]

Thanks, I'll study it.

[help-14]

@suicidal_orange : I did some research and write down the digital code to the pins, but I can only found 24 of them. You said some special port can be use too so which are the last two

[suicidal_orange]

I didn't say it, the datasheet did

Having just woken up inverting the pinout on a tiny screen is not going well, I've spotted 22 as one of them but can't see the other - figure 2 here has 26 pins labelled PAx so it's whichever of them you've not used.

[help-14]

It is the pin 22
Just done wiring all the stuff, re-check twice, now print and test https://github.com/help-14/tkl-mechkey

[suicidal_orange]

You said you'd only found 24 pins, plus pin 22 you're still missing one?

Also 'print and test', you're etching it yourself?!

[help-14]

I asked Moz and he said there are only 25 pin available. So I re-wiring the last column and made it a row, so I can have the last pin for RGB.
I'l send it to printing shop, can't do it myself :v

[suicidal_orange]

Ah that makes sense, a DIY RGB PCB would be quite something!

How do Atmel get away with that false advertising though, is that not a thing in the US?  I thought you'd have bought 100, found them unsuitable for purpose, then sued for emotional distress )

[help-14]

Haha, maybe it is 26, but Moz said I shouldn't use port 33  But who care, i'll call my lawyer