Concept Custom front panel IO

ninjanymo

Caliper Novice
Original poster
Jun 16, 2018
21
13
I've been considering building a custom front panel for my on going build and I was wondering if anyone had some experience in this.

Getting PCBs made is extremely cheap nowadays and designing the front panel from scratch gives that sweet sweet full design freedom.

The power and reset buttons are simple, just short the pins somehow and you are good.

For the LEDs I've always used current limiting resistors in series just to be sure. I've tried to figure out if these are required as the LED pins might already be current limited on the motherboard. Does anyone know? I guess asking the motherboard manufacturer might be a good place to start.

Then the USB ports. It's kinda weird that I can't seem to find any documentation on this, but it seems as if you can just connect the pins to a header and you should be good to go. Might be a good idea to add some TVS diodes for ESD events, but as with the LEDs, there might already be sufficient functionality implemented in the motherboard.

Also, with USB3 you are working with very high frequency signals where shielding and impedance control of the PCB is something to consider. Something tells me this is not as straight forward as it might seem.

Thoughts on doing fully custom IO, let's call it breakout boards?
 
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el01

King of Cable Management
Jun 4, 2018
770
588
I've been considering building a custom front panel for my on going build and I was wondering if anyone had some experience in this.

Getting PCBs made is extremely cheap nowadays and designing the front panel from scratch gives that sweet sweet full design freedom.

The power and reset buttons are simple, just short the pins somehow and you are good.

For the LEDs I've always used current limiting resistors in series just to be sure. I've tried to figure out if these are required as the LED pins might already be current limited on the motherboard. Does anyone know? I guess asking the motherboard manufacturer might be a good place to start.

Then the USB ports. It's kinda weird that I can't seem to find any documentation on this, but it seems as if you can just connect the pins to a header and you should be good to go. Might be a good idea to add some TVS diodes for ESD events, but as with the LEDs, there might already be sufficient functionality implemented in the motherboard.

Also, with USB3 you are working with very high frequency signals where shielding and impedance control of the PCB is something to consider. Something tells me this is not as straight forward as it might seem.

Great idea!
Would it have USB ports sticking up or sideways (in relation to PCB)?
 
Last edited:

owliwar

Master of Cramming
Lazer3D
Apr 7, 2017
585
1,081
thats something I'd like to know more as well.
I dont really care about the usb part, I was manly interested in the audio ports.

is really difficult to get a symmetric layout with power button on middle, and one audio port on each side or whatever.
 

ninjanymo

Caliper Novice
Original poster
Jun 16, 2018
21
13
Great idea!
Would it have USB ports sticking up or sideways (in relation to PCB)?

I would actually like to have the USB ports sticking down and then have a cutout in the PCB, but I can't seem to find any USB header that does that.

thats something I'd like to know more as well.
I don't really care about the USB part, I was manly interested in the audio ports.

is really difficult to get a symmetric layout with power button on middle, and one audio port on each side or whatever.

The audio signals is a completely different challenge as it's analog signals. I have generally steered away from front-panel audio as it's very susceptible to noise. You would have to get a shielded cable and then figure out how to properly terminate the shielding at the custom PCB. Things to consider would be having as little as possible copper trace on the PCB between the 3.5mm connector and the connector going to the cable to the motherboard. It would probably be best to have a 4-layered (only 3 layers needed but I don't think people make those) where you have the copper traces carrying the audio signals sandwiched between two solid copper planes (aka copper pours).

If someone with better understanding of analog signal integrity has something to point out here, please do.

As for USB3 I've done some research and it seems to be necessary to do proper impedance control and termination of the traces carrying the signals. It would probably be best to buy premade cables with headers on the other end.

USB2, power switch and LEDs are very straight forward stuff, although I haven't found out how you need to balance ESD protection and current limiting on your own PCB with what is already on the motherboard.
 
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