Did I wire this properly? or is it going to explode and then swallow the ground from beneath me

[NoobKing]

I’m completely new to Kicad and was wondering if someone could lookover and make sure I wired my schematic properly, i’m trying to make a fighting keyboard with some RGB LED’s that i’ll hopefully be able to control through some software. Any help/tips/advice/explanations is greatly appreciate

Libraries used: Marbastlib, Keyswitch Kicad Library
Project File: Fighting Keyboard ver 1 - Google Drive

[devbisme]

I don’t know what a fighting keyboard is, but it sounds interesting. I can’t make out what is really going on with that color scheme. Is that the default now!? Yowza! You also need a bigger image than 1200px wide.

I assume some type of microcontroller attaches to that connector on the left-hand side?

On cursory inspection, it looks like it might work. Make sure the microcontroller never drives a row and column simultaneously since there are no current-limiting resistors. (Correction: I guess those diodes prevent that.) (Further correction: Maybe not if you drive a column high and pulled a row low, there could be a problem.)

Also, put some pull-down resistors on the row lines so they don’t float when no buttons are pressed.

Also, you might connect the serial output from your last LED back to pin 9 of the connector. Then your microcontroller can check the integrity of the serial connections by looking at that (I think).

Also, be prepared to hear “This forum is intended to answer questions about KiCad. General questions about electronics should be directed elsewhere. Closing this thread.” That should be coming in 3…2…1…

[devbisme]

Oh, one more thing: Can you just use a socket for something like a XIAO RP2040? It has 14 I/O pins and you only need 11. Then you would only need to build the board with LEDs and the switches. The USB-C is already included on the XIAO. And then you could program it using Python or via the Arduino IDE through the USB.

[NoobKing]

Thank you so much for the help, you’re a Godsend for a newbie like me . I’ll look into the XIAO RP2040 as that seems like a really great idea (along with all the other advice you’ve given me), and the website it links to seems to have a lot of other important info too.

[NoobKing]

I don’t know if this reply will reach you, but I have a quick question about the micro controller you recommended me. In the schematic, the micro controller has 3 GND pins on it, is it necessary to provide ground to all 3 pins, or are they just recommended GND areas (in the sense to just choose 1 of the 3)?

[paulvdh]

@NoobKing

is it necessary to provide ground to all 3 pins,

Yes, always connect all GND pins of a IC to each other, and do that on a good GND plane. Also combine it with decent routing of the power net and well placed decoupling capacitors. (Although the RP2040 likely already has decoupling capacitors.

[NoobKing]

@paulvdh

always connect all GND pins of a IC to each other

When you say this do you mean, connect all the GND pins by a wire leading them all to the same GND symbol, or should I give a GND symbol to each GND pin?

[paulvdh]

Oopsie, I missed the:

@NoobKing

In the schematic

part of your earlier post.
In the schematic it (technically) does not matter. You can use labels, GND symbols or wires, whatever suits your purpose or what you think looks best.
I was only referring to the PCB. PCB design needs to be done “properly”. There are folks who try to mimic the way the PCB should be designed in the schematic too, but that is something I do not agree with personally.

[NoobKing]

Thanks, I greatly appreciate it.

[Piotr]

@NoobKing

In the schematic, the micro controller has 3 GND pins on it,

I didn’t searched for this microcontroller but microcontrollers in cases without grounded thermal pad frequently have VCC,GND pin pairs located at their sides. And at each pair there should be blocking capacitor and GND and VCC should be connected to all of them.
It is because of EMC. The area surrounded by current pulses should be as small as possible. The shortest way back for return current of pulses at uC pins at right side is if there is (inside uC case) the GND wire from right case size to chip (imagine the chip as a small point in the case center). The same for other case sides. Also power pulse currents should have as small area as possible so it is best if VCC and GND wires (inside iC case) are parallel and close to each other. So next to each GND pin there is VCC pin and at each pair there should be blocking capacitor to let power supply pulses have as short way to IC chip as possible.
See the PCB I showed (for different reason) here:

Approaching PCB track routing for a newbie

Positioning for me is the main work in designing PCB. If each element is where it is needed than routing is simple. Till now all my PCBs are 2 layers and all of them have GND plane taking 100% of bottom layer. So except GND I design my PCBs as 1 layer. I use microcontrollers in QFP packages without thermal pad at bottom. This allows me to go with VCC under the microcontroller and go out through all corners and all VCC pins. That way GND and VCC don’t disturb my signal connections. At all digi…

At center is uC. You can find 6 pins connected to VCC (VC) and at each of them there are 0402 capacitor to next pin that is connected to GND (all vias at this picture are GND).