Author Topic: The Living PCB Design Thread  (Read 127031 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?


Online 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.

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Offline _haru

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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.
Quote from: My friend Ellie
It's not da bomb, it's A bomb.

Boards: AMJ60 (45g MX White), SMK-8851 (SKBM White Alps), Let's Split (Holy Greilh Red), XD64 LapBoard (55g Gateron Tactile Clear), Bleach60 (SMK White), GH60 Satan (Kailh Yellow)

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?

Online 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


Online 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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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


Online kamilakas

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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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Online kamilakas

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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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Offline Irlwizard

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Re: The Living PCB Design Thread
« Reply #622 on: Wed, 27 September 2017, 21:30:28 »
Found a PCB building guide. Nothing I can personally attempt but some of you might find it useful.

Link: https://github.com/ruiqimao/keyboard-pcb-guide

Online TalkingTree

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Re: The Living PCB Design Thread
« Reply #623 on: Thu, 28 September 2017, 08:51:40 »
I've seen this on quite a few PCBs but I need some help understanding how it works.

179201-0


Those are supposed to be stepped and regular caps lock so they share the same diode.

If the two switch pads are overlapped, how is this not shorting?

My projects: Skipad, Toad.

Offline Tiramisuu

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Re: The Living PCB Design Thread
« Reply #624 on: Thu, 28 September 2017, 11:53:58 »
A bit off topic but...

What do you use for staring at PCB's when working on them.

My little plastic 5x monocle lets me squint at a PCB but it won't be terribly comfortable
while placing smd parts with tweezer and cooking them on with a hot air gun.   I should probably buy a little toaster oven as well.

thanks,
t.
Keyboard error F1 to continue.

Poker 2, Gherkin, Lets Split, Planck, Filco

Offline bpiphany

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Re: The Living PCB Design Thread
« Reply #625 on: Thu, 28 September 2017, 23:16:25 »
I've seen this on quite a few PCBs but I need some help understanding how it works.

Those are supposed to be stepped and regular caps lock so they share the same diode.

If the two switch pads are overlapped, how is this not shorting?

The diode is probably connected to both the outer pads and the middle pad to the "other side" of the matrix. If the switch pins are A and B, current flows from A-B in one position and B-A in the other, the switch really doesn't care.


What do you use for staring at PCB's when working on them.

I find that the strongest reading glasses (+4) you find at the cheap places is enough for a lot of work. For inspecting stuff where I have a free hand anyway I use a 10X hand held loupe, I don't find that too inconvenient.

You can find "glasses" like these very cheap on ebay as well
« Last Edit: Thu, 28 September 2017, 23:21:10 by bpiphany »

Online TalkingTree

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Re: The Living PCB Design Thread
« Reply #626 on: Fri, 29 September 2017, 02:46:29 »
I've seen this on quite a few PCBs but I need some help understanding how it works.

Those are supposed to be stepped and regular caps lock so they share the same diode.

If the two switch pads are overlapped, how is this not shorting?

The diode is probably connected to both the outer pads and the middle pad to the "other side" of the matrix. If the switch pins are A and B, current flows from A-B in one position and B-A in the other, the switch really doesn't care.
That was so obvious that I feel dumb. Thank you so much for your clarification.
My projects: Skipad, Toad.

Offline Tiramisuu

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Re: The Living PCB Design Thread
« Reply #627 on: Fri, 29 September 2017, 16:29:09 »
... and thanks for the help...



V1 is slowly becoming something.
Keyboard error F1 to continue.

Poker 2, Gherkin, Lets Split, Planck, Filco

Online TalkingTree

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Re: The Living PCB Design Thread
« Reply #628 on: Fri, 29 September 2017, 16:35:11 »
... and thanks for the help...

Show Image


V1 is slowly becoming something.
So... ALPS or MX?
My projects: Skipad, Toad.

Offline Tiramisuu

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Re: The Living PCB Design Thread
« Reply #629 on: Fri, 29 September 2017, 17:00:11 »
... and thanks for the help...

Show Image


V1 is slowly becoming something.
So... ALPS or MX?

MX - Kailh Speed Silvers with custom 15cN springs @ 2MM.   
The speed silvers have a 1.1mm activation point so I am hoping for about 12cN activation.

I may look at the Cherry Speeds as well 1.2mm activation point but I'd like to see if the manufacturing tolerances are better.

...  I'm also going to try the Kailh Low Profile switches on one of the prototypes if they are willing to send me some keycaps.

... I have a gherkin with the gat whites and a planck with the Matias reds here and when my spring order comes in from China I will be trying them on all the different switches here to see how they feel. 

I will be assembling 5 prototypes to send around for steno folks to try so I will likely do 5 different switch configurations for them to try.   The Matias have the advantage of being dead easy to swap springs on but the higher activation point of the speeds and the low profiles with their decreased travel and higher activation points are also appealing.

It is a shame that the newest kailh (2017) low profile switches are't being manufactured in a linear version.

Keycaps wise... I will start with dremelled down G20's but I would love to find a nice solution both for 16mm steno keycap and full size steno keycaps.    Home row position is between the rows in steno and you press many keys at a time (chording) ... So this means a Flat Key to with close edges and enough thickness that it doesn't catch your finger tips is desirable.
 


Keyboard error F1 to continue.

Poker 2, Gherkin, Lets Split, Planck, Filco

Online dr_derivative

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Re: The Living PCB Design Thread
« Reply #630 on: Thu, 02 November 2017, 13:05:11 »
Does anyone know where I can find a footprint for SMK 2nd gen switches?

I have a bunch of those switches incoming but I want to be able to start the PCB design before they arrive.

Online TalkingTree

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Re: The Living PCB Design Thread
« Reply #631 on: Thu, 02 November 2017, 15:04:05 »
Does anyone know where I can find a footprint for SMK 2nd gen switches?

I have a bunch of those switches incoming but I want to be able to start the PCB design before they arrive.
These gentlemen made a 60% PCB for those switches, they are likely to have what you're looking for.
My projects: Skipad, Toad.

Offline _haru

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Re: The Living PCB Design Thread
« Reply #632 on: Thu, 02 November 2017, 22:37:14 »
Does anyone know where I can find a footprint for SMK 2nd gen switches?

I have a bunch of those switches incoming but I want to be able to start the PCB design before they arrive.
These gentlemen made a 60% PCB for those switches, they are likely to have what you're looking for.

There's also an XD64/HHKB JP layout version coming with support for SMK and MX switches.
Quote from: My friend Ellie
It's not da bomb, it's A bomb.

Boards: AMJ60 (45g MX White), SMK-8851 (SKBM White Alps), Let's Split (Holy Greilh Red), XD64 LapBoard (55g Gateron Tactile Clear), Bleach60 (SMK White), GH60 Satan (Kailh Yellow)

Online dr_derivative

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Re: The Living PCB Design Thread
« Reply #633 on: Fri, 03 November 2017, 06:19:12 »
Does anyone know where I can find a footprint for SMK 2nd gen switches?

I have a bunch of those switches incoming but I want to be able to start the PCB design before they arrive.
These gentlemen made a 60% PCB for those switches, they are likely to have what you're looking for.

Thanks, I'll send them a PM

Offline farhai

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Re: The Living PCB Design Thread
« Reply #634 on: Sun, 05 November 2017, 17:41:48 »
sorry sir i want to ask about the atmega32u4

i look the datasheet and there is two variant atmega32u4 and atmega32u4RC
what should i choice?

thanks

Offline bpiphany

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Re: The Living PCB Design Thread
« Reply #635 on: Mon, 06 November 2017, 03:16:00 »
sorry sir i want to ask about the atmega32u4

i look the datasheet and there is two variant atmega32u4 and atmega32u4RC
what should i choice?

thanks

The RC version is pre-programmed to use the internal 8MHz oscillator. You most probably don't want that one. You would need a programmer to change the fuse settings to be able to use it (easily) with USB. I also believe the none-RC version is more readily available anyway.

Edit: I forgot that the RC version comes without a bootloader, since it's not intended to be used for USB anyway.
« Last Edit: Tue, 07 November 2017, 02:37:26 by bpiphany »