Author Topic: The Living PCB Design Thread  (Read 115015 times)

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Offline ishtob

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Re: The Living PCB Design Thread
« Reply #600 on: Fri, 25 August 2017, 22:55:57 »
the resistors between the usb and the MCU should prob be closer to the USB, though in a low speed application like a keyboard it prob won't matter nearly as much.

the resistor and cap ground you go there should be fine.

Offline hasu

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Re: The Living PCB Design Thread
« Reply #601 on: Fri, 25 August 2017, 23:36:26 »
the resistors between the usb and the MCU should prob be closer to the USB, though in a low speed application like a keyboard it prob won't matter nearly as much.

the resistor and cap ground you go there should be fine.

Yes, I've saw the resisters placed close to USB receptacle in some keyboard PCBs, not a few.
I'm curious about what theory or reason behind that practice is. Do you know document or something about this?

I found contrary practice in one of Atmel app notes and I've followed this and I place the resisters on D- and D+ line close to MCU in my PCB.
I cannot find the app note now I'll post it here later if I find.
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Offline ishtob

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Re: The Living PCB Design Thread
« Reply #602 on: Sat, 26 August 2017, 00:06:24 »
 I guess I was under the mistaken impression that this resistor was meant to stop EMI from entering the device, therefor, placing it near the USB connectors made sense.

Looking through some papers online it isn't too much of an issue except for people using parallel terminations.
http://www.ultracad.com/mentor/mentor%20termination%20placement.pdf

Offline dead_pixel_design

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Re: The Living PCB Design Thread
« Reply #603 on: Sat, 26 August 2017, 00:25:57 »
Thanks guys! Gonna tune in the screw holes and send it out for prod

Offline hasu

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Re: The Living PCB Design Thread
« Reply #604 on: Sat, 26 August 2017, 01:19:54 »
I guess I was under the mistaken impression that this resistor was meant to stop EMI from entering the device, therefor, placing it near the USB connectors made sense.

Looking through some papers online it isn't too much of an issue except for people using parallel terminations.
http://www.ultracad.com/mentor/mentor%20termination%20placement.pdf

Thanks for clarifying.

So simple practice for us hobbyists is:

ESD/EMI protection deivces should be placed near USB receptacle while termination(impedance matcning) resistors should be placed near controller.

We already know empirically that it doesn't matter very much for keyboards, though, this simple design guide will be still helpful for us.


I couldn't find good reference for placement of termination resistors but these docs imply it.

EFM32 USB Hardware Design Guide p.5
https://www.silabs.com/documents/public/application-notes/AN0046.pdf

Atmel High Speed USB Design Guidelines p.3
http://www.atmel.com/images/doc7633.pdf
« Last Edit: Sat, 26 August 2017, 01:21:33 by hasu »
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Offline ishtob

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Re: The Living PCB Design Thread
« Reply #605 on: Sat, 26 August 2017, 11:44:29 »
I guess I was under the mistaken impression that this resistor was meant to stop EMI from entering the device, therefor, placing it near the USB connectors made sense.

Looking through some papers online it isn't too much of an issue except for people using parallel terminations.
http://www.ultracad.com/mentor/mentor%20termination%20placement.pdf

Thanks for clarifying.

So simple practice for us hobbyists is:

ESD/EMI protection deivces should be placed near USB receptacle while termination(impedance matcning) resistors should be placed near controller.

We already know empirically that it doesn't matter very much for keyboards, though, this simple design guide will be still helpful for us.


I couldn't find good reference for placement of termination resistors but these docs imply it.

EFM32 USB Hardware Design Guide p.5
https://www.silabs.com/documents/public/application-notes/AN0046.pdf

Atmel High Speed USB Design Guidelines p.3
http://www.atmel.com/images/doc7633.pdf

The atmel documentation did specify to have the termination resistor as close to the signal pin as possible (section 2.3)

Thanks for your awesome insight!


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Online feraphic

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Re: The Living PCB Design Thread
« Reply #606 on: Sat, 26 August 2017, 15:44:01 »
Do I need to connect two pads with traces if they're already overlapping each other, or is that just redundant?


Offline TalkingTree

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Re: The Living PCB Design Thread
« Reply #607 on: Sat, 26 August 2017, 17:36:06 »
Do I need to connect two pads with traces if they're already overlapping each other, or is that just redundant?
It's redundant because they are already connected, but it doesn't harm  to trace a wire.
My projects: Skipad, Toad.

Offline bpiphany

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Re: The Living PCB Design Thread
« Reply #608 on: Sun, 27 August 2017, 01:01:53 »
In some cases it may even be bad to create loops like that. Here it won't matter. You may still want to connect them with a short short trace between the center of the pads to let the ERC know they are connected.

And beef up the traces, that just looks silly...

Offline Tiramisuu

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Re: The Living PCB Design Thread
« Reply #609 on: Thu, 31 August 2017, 23:50:08 »
Trying to layout my first PCB.

I am doing a very small layout; 26 keys
Going with a 16mm design so the switches will be very close together and using cut-down keycap and/or custom cap.
Planning on using a pro-micro



Installed Kicad and Eagle this evening then started thinking there is probably an easier way than doing everything from scratch... So here I am.

The layout is going to be the similar to a 16MM Edward or a shrunk down Gherkin only the bottom row will be offset 50% and 4 of the keys in the bottom row will be removed.

I can find gerber files for the gherkin and the 16mm Edward but no kicad/eagle project files.

I can create a layout with the keyboard-layout-editor with the layout I want but the wrong switch spacing then try to use kacelerator...   Which doesn't seem to be working properly with Eagle 7.6 or I have to hack something to actually get the scr to run to generate the initial schematic and board.

... I found the gh60 kicad project files ... I could use this as a starting point and then reduce it to my intended design.

I could start with a blank slate and work from tutorials and try to build the design from scratch using the other gerbers and kicad projest as reference.


My object is to end with a working PCB for my custom keyboard rather than learn everything there is to know about creating PCBs. (So quick and easy rather than an educational event)

What is the easy way to get to end of project on this?   


thanks,
T

« Last Edit: Fri, 01 September 2017, 00:21:42 by Tiramisuu »
Keyboard error F1 to continue.

Poker 2, Gherkin, Lets Split, Planck, Filco

Online linuxfanatic

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Re: The Living PCB Design Thread
« Reply #610 on: Sun, 03 September 2017, 02:53:16 »
Trying to layout my first PCB.

I am doing a very small layout; 26 keys
Going with a 16mm design so the switches will be very close together and using cut-down keycap and/or custom cap.
Planning on using a pro-micro

Show Image


Installed Kicad and Eagle this evening then started thinking there is probably an easier way than doing everything from scratch... So here I am.

The layout is going to be the similar to a 16MM Edward or a shrunk down Gherkin only the bottom row will be offset 50% and 4 of the keys in the bottom row will be removed.

I can find gerber files for the gherkin and the 16mm Edward but no kicad/eagle project files.

I can create a layout with the keyboard-layout-editor with the layout I want but the wrong switch spacing then try to use kacelerator...   Which doesn't seem to be working properly with Eagle 7.6 or I have to hack something to actually get the scr to run to generate the initial schematic and board.

... I found the gh60 kicad project files ... I could use this as a starting point and then reduce it to my intended design.

I could start with a blank slate and work from tutorials and try to build the design from scratch using the other gerbers and kicad projest as reference.


My object is to end with a working PCB for my custom keyboard rather than learn everything there is to know about creating PCBs. (So quick and easy rather than an educational event)

What is the easy way to get to end of project on this?   


thanks,
T

I know I might get a bit of hate for this but if your end goal is to have a working PCB, it might be easier to just etch your own PCB.
The LF60 project is dead. Please don't ask me to buy one etc.

Offline dead_pixel_design

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Re: The Living PCB Design Thread
« Reply #611 on: Thu, 07 September 2017, 05:40:55 »
Does it matter which way caps/resistors are attached? Do they have polarity?

Offline TalkingTree

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Re: The Living PCB Design Thread
« Reply #612 on: Thu, 07 September 2017, 06:17:30 »
Does it matter which way caps/resistors are attached? Do they have polarity?
Resistors and ceramic capacitors don't, electrolytic capacitors are polarized.
My projects: Skipad, Toad.

Offline jjanssen1

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Re: The Living PCB Design Thread
« Reply #613 on: Sat, 09 September 2017, 04:54:30 »
Two key ATTINY85 Osu/Macropad I designed :)

Silver KBD75 with Gateron Browns & GMK Monkey


Offline TalkingTree

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Re: The Living PCB Design Thread
« Reply #614 on: Sat, 09 September 2017, 05:44:40 »
Two key ATTINY85 Osu/Macropad I designed :)

Show Image

That looks cool. What are you using it for?
My projects: Skipad, Toad.

Offline jjanssen1

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  • Location: Melbourne, Australia
Re: The Living PCB Design Thread
« Reply #615 on: Sat, 09 September 2017, 07:03:55 »
Two key ATTINY85 Osu/Macropad I designed :)

Show Image

That looks cool. What are you using it for?

I will be using it for playing Osu!
Silver KBD75 with Gateron Browns & GMK Monkey


Offline kamilakas

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  • Location: Russia, Kazan
Re: The Living PCB Design Thread
« Reply #616 on: Wed, 13 September 2017, 11:24:14 »
Hi, guys! I'm bulding my own ergodox for school project as an innovative kbd layout. So, I found all sources of IC's version of ergodox. I have question - if I'll order PCBs and then will solder all the components, will there be an option to flash the keyboard via usb? Or I'll need some kind of programming device for microcontrollers?

Offline yuktsi

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Re: The Living PCB Design Thread
« Reply #617 on: Wed, 13 September 2017, 11:42:42 »
Hi, guys! I'm bulding my own ergodox for school project as an innovative kbd layout. So, I found all sources of IC's version of ergodox. I have question - if I'll order PCBs and then will solder all the components, will there be an option to flash the keyboard via usb? Or I'll need some kind of programming device for microcontrollers?
You will need a programmer, at least for the first time. I think.
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Offline kamilakas

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  • Location: Russia, Kazan
Re: The Living PCB Design Thread
« Reply #618 on: Wed, 13 September 2017, 11:52:49 »
Hi, guys! I'm bulding my own ergodox for school project as an innovative kbd layout. So, I found all sources of IC's version of ergodox. I have question - if I'll order PCBs and then will solder all the components, will there be an option to flash the keyboard via usb? Or I'll need some kind of programming device for microcontrollers?
You will need a programmer, at least for the first time. I think.
So, PCB have some direct controller outputs. Will I have possibility with this pins?

Offline yuktsi

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Re: The Living PCB Design Thread
« Reply #619 on: Wed, 13 September 2017, 12:09:13 »
Hi, guys! I'm bulding my own ergodox for school project as an innovative kbd layout. So, I found all sources of IC's version of ergodox. I have question - if I'll order PCBs and then will solder all the components, will there be an option to flash the keyboard via usb? Or I'll need some kind of programming device for microcontrollers?
You will need a programmer, at least for the first time. I think.
So, PCB have some direct controller outputs. Will I have possibility with this pins?
I've no experience with ergodox, but I think you will need to have connection to the MISO, MOSI, SCK, RESET, VCC and GND
More
Poker 2 | LZ CE | Leopold FC700R | KMAC 1.2 | EXE | GON NS87 | GON Nerd TKL | Duck Poker | Duck Orion | Realforce 87u 55g | OTD 456GT | LZ B7 | OTD 360C | Ducky G2 Pro | Apple Extended | Apple M0116 | Apple M0116 | Cherry G80-1220HAD | Duck Octagon | HHKB Pro 2 | Duck Unicorn | LZ B8 | LZ RE | ENVKX | OTD 456GT | LZ FE | HHKB Type S | TX1800| Duck Orion V2 | LZ FE | KPad | KMAC Happy | ENVKX | LZ RV | KMAC 2 | Whale | Dolphin | EM7 | TGR Jane | VE.A | DK Saver | Matrix 103 | Whale | HHKB BT | Dolphin v2 | EM7 v2 | SSK | SSK (Blue Label) | LZ SQ | Duck Octagon v2 | TX84 | GON Mobik | TX-CP | LZ Ergo | KMAC Happy HHKB | TGR 910 | TGR Tris | Matrix 8xv1.2 | KMAC Mini | Mira | Fjell | 356mini | Dolphin GH | EM7 GH | TARO EXENT | Masterkey Pro L Crystal

Offline bpiphany

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Re: The Living PCB Design Thread
« Reply #620 on: Wed, 13 September 2017, 12:48:09 »
Which microcontroller is it? ATmega32u4? In that case it will come with a bootloader to enable flashing over USB.

Be careful not to get the ATmega32u4RC though. It doesn't come with the loader and will need serial programming.


Found out that it's something completely different.
« Last Edit: Wed, 13 September 2017, 12:55:08 by bpiphany »

Offline hasu

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Re: The Living PCB Design Thread
« Reply #621 on: Wed, 13 September 2017, 13:03:29 »
Hi, guys! I'm bulding my own ergodox for school project as an innovative kbd layout. So, I found all sources of IC's version of ergodox. I have question - if I'll order PCBs and then will solder all the components, will there be an option to flash the keyboard via usb? Or I'll need some kind of programming device for microcontrollers?
You will need a programmer, at least for the first time. I think.
So, PCB have some direct controller outputs. Will I have possibility with this pins?
I've no experience with ergodox, but I think you will need to have connection to the MISO, MOSI, SCK, RESET, VCC and GND

Seems like Kinetis K20 series don't have USB bootloader at factory shipment and you have to program it with JTAG, SWD or something. I think I:C use Segger J-Link with Tag-Connect cable via P1 pinouts in their fab but you can find cheaper alternative apparatus. You may want/have to check datasheet and appnotes for checking if pinouts(P3) has pins enough for program and program methods.
https://www.nxp.com/docs/en/application-note/AN4835.pdf
Kinetis K20_72
« Last Edit: Wed, 13 September 2017, 13:07:21 by hasu »
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