Goldfish v2 - A super thin USB-C Pro Micro clone

[dr_derivative]

Goldfish v2

Goldfish is a Pro Micro compatible microcontroller board designed for use in mechanical keyboards. It is based on the same Atmel ATMega32U4 chip and is programmable using the Arduino IDE or a keyboard specific firmware such as TMK or QMK. Of course it is perfectly usable for any other electronics projects too, not just keyboards.



Github repo

Features

• Lower board profile with the mid-mounted USB-C connector
• Two internal pins make the USB data lines easily accessible
• USB-C is more durable, reversible and just plain cool
• 5 additional pins on the bottom edge of the board
• Pin-compatible with the original Pro Micro
• Sturdier through-hole USB connector
• On board ESD protection for USB lines

Changes compared to Goldfish v1

• Addition of on board ESD protection and fuse
• All 0603 resistors and capacitors for (slightly) easier hand assembly
• Castellated edge connectors similar to the Elite-C
• Less obscure USB-C connector
  • Use of more commonly available components in 2022
  • Choice between multiple compatible connectors and suppliers
  • Uses USB 2.0-only connector for easier and cheaper assembly

Disadvantages

• No onboard RX, TX LEDs
• No onboard voltage regulator (this makes no difference for keyboards; a regulator is only required when power supplies of over 5.5V are used)
• No onboard reset button

Vendors Selling Goldfish

Goldfish v1 rev. C

• BeeKeeb

Comet (modified design based on Goldfish v1; see related projects)

• Tokas' Kable Works

Note: These products are sold by 3rd party vendors and are not 'officially' endorsed by me. I'm simply listing them here for convenience.

(Also please let me know if anything is missing from this list)

Related Projects

Alvaro by Ariamelon

• A modified Goldfish v1 using 0603 components instead of 0402

Comet by Tokas

• A modified Goldfish v1 using a HRO TYPE-C-31-M-12 connector

Whale by Jia Geng Chang

• A modified Goldfish v1 using a Jing 918-418K2024S40000 connector

Goldfish-clone-JLCPCB by Jeremy J Starcher

• A modified Goldfish v1 designed to meet JLCPCB's assembly requirements

Elite-C from keeb.io

• An unrelated and closed source project with similar design goals

(Please let me know if anything is missing form this list)

Old Goldfish v1 info:

More

Introduction
During my free time over the past couple of months I've been playing around with KiCad designing this. I have no idea if anyone will be interested, but whatever.  )
For now I've named it 'Goldfish', mainly because I drew a cartoony goldfish when I was bored and have used that as artwork on the PCB. Also, like a goldfish, it's small.
It is pin compatible with a regular Pro Micro, uses the same ATMega32u4. It uses a mid-mounted USB-C connector to make the board thinner while making the connector more durable than the usual SMD connector.

Pics
I only have renders for now, I will order prototypes soon. Soldermask will probably be yellow to fit in with the goldfish theme.
The USB-C connector isn't shown since KiCad doesn't have a model for it, but it will look something like the picture below.





Advantages (over a Pro Micro)

• The through-hole USB connector is much less likely to break off compared to surface mount connectors.
• USB-C is reversible, more durable and just plain cool.
• Pin-compatible with the original Pro Micro and Pro Micro clones.
• Goldfish has five extra pins available along its bottom edge if more pins are required.
• USB data lines are easily accessible through two internal pins.
• A mid-mounted USB-C connector allows goldfish to be much thinner than a Pro Micro.

Disadvantages (over a Pro Micro)

• Fewer custom cable options for USB-C when compared to Mini-B/Micro-B.
• More expensive (depends on MOQ of course).
• No onboard voltage regulator (this makes no difference for keyboards; an external regulator is only required when power supplies of over 5.5V are used).
• No onboard RX, TX or Power indicator LEDs.

CAD Files
CAD file are on GitHub at https://github.com/Dr-Derivative/Goldfish.

Disclaimer
I haven't tested this board yet. If you decide to have a few of these produced do so at your own risk!
Edit: Others have tested it and it looks like it works well

[synonzelra]

I would still say some regulator is required since there might be spikes when pluging or unpluging.

[suicidal_orange]

This looks great - compatible yet better as it has more pins

I don't think the missing LEDs are a disadvantage either, if you can see the power one under your keyboard you can see the cable is plugged in and TX/RX just complicate things when choosing pins for the matrix.

[dr_derivative]

I would still say some regulator is required since there might be spikes when pluging or unpluging.

I don't think this will be much of an issue; there are plenty of PCBs based on the ATMega32u4 without any form of voltage regulator. I can add some TVS diodes if transients do end up being a problem, but I doubt it's needed.

This looks great - compatible yet better as it has more pins

Thank you

[steinerlein]

I think this is a great idea! Would be interested in a couple of these, depending of the price of course..

[dr_derivative]

I think this is a great idea! Would be interested in a couple of these, depending of the price of course..

Price will be a bit more than the average Pro Micro clone on Ebay, but probably still under $10.

[ZayaCaps]

This is great! I would definitely buy these if the price is under $10.

[synonzelra]

Here's something up to me about type-c. How do you connect a usb2.0 interface into type-c module?

I mean, 32u4 has only a group of D+ and D- while type-c has two.

To make it reversible you need to connect to both groups in type-c.

But this won't work on a real type-c port from host.

[dr_derivative]

USB-C can be very complicated but for a USB 2.0 or 1.1 device (like a keyboard) it's actually not that much more complicated than Mini-B or Micro-B. You connect both D+ and D- pins together and just connect them like you would normally. All the VBUS pins are connected together as are all GND pins. Both CC pins are connected through 5.1k resistors to ground. All other pins aren't used and can be left open. Have a look at my github if you want to see schematics.

[MatchstickMan]

This is excellent! I'm definitely interested in a buy for these.

It might be equally interesting to match the pro-micro layout of pins, USB connector, and such for direct retrofitability with the Pro Micro.

[dr_derivative]

This is excellent! I'm definitely interested in a buy for these.

It might be equally interesting to match the pro-micro layout of pins, USB connector, and such for direct retrofitability with the Pro Micro.

Pin layout is identical, it can be used as a direct replacement for a Pro Micro. It just has a couple extra pins along the bottom for hand wired builds  .
 

[MatchstickMan]

Pin layout is identical, it can be used as a direct replacement for a Pro Micro. It just has a couple extra pins along the bottom for hand wired builds  .

Awesome, but if the USB location is different (top mounted vs center mounted), it could be an issue for existing cases. For instance, there are a number of Lets Split cases that may not be compatible with this configuration.

Of course, center-mount should be the default because the space savings is fantastic, but it may be worth having a second configuration that has the USB-C port top mounted just for retrofitability purposes.

Alternatively, the cases may have holes large enough that it doesn't matter. In which case IGNORE ME.

[dr_derivative]

Pin layout is identical, it can be used as a direct replacement for a Pro Micro. It just has a couple extra pins along the bottom for hand wired builds  .

Awesome, but if the USB location is different (top mounted vs center mounted), it could be an issue for existing cases. For instance, there are a number of Lets Split cases that may not be compatible with this configuration.

Of course, center-mount should be the default because the space savings is fantastic, but it may be worth having a second configuration that has the USB-C port top mounted just for retrofitability purposes.

Alternatively, the cases may have holes large enough that it doesn't matter. In which case IGNORE ME.

I think most let's split cases have a fairly loose fit around the connector since the Pro Micro attaches upside down on one half. Also, one of the main advantages of the slimmer controller is that the whole keyboard can be made slimmer, so a different, thinner case could be used anyway. That being said, it's not too difficult to adapt the design with a top mounted connector if there's demand. I guess we'll find out if this gets to IC phase  .

[monkeyplusplus]

These look super fun! Will these be flashable with dfu?

[dr_derivative]

These look super fun! Will these be flashable with dfu?

I'm not sure what I'll do about the bootloader since the QFN version of the ATMega32u4 comes without one pre-installed. I could flash the Pro Micro's default bootloader which uses AVRDude or LUFA DFU which uses DFU-programmer.

[monkeyplusplus]

Personally, I would prefer dfu, since it's a little easier to flash. That's my vote. Curious to hear what others would think

[dr_derivative]

I've updated the CAD files on Github to fix the split keyboard issue. I don't have any time at the moment to do any prototyping or testing, I'm far too busy with other things. But if anyone wants to order a few of these things to test themselves feel free.

Cartel have just started an IC for Pro Micros with various connectors including USB-C, so if you want a type-C Pro Micro you can have a look here. I'll probably still run a groupbuy for the Goldfish at some stage, but as I said I'm far too busy with other things at the moment  ) .

[concinnus]

Thanks for the update, mang.  It's far more than I expect from someone who's gotten too busy.

[Lbibass]

I really, really like this! Super excited for this. Do you know if it works?

edit: I am a fool, you haven't tested it yet.

[dr_derivative]

I really, really like this! Super excited for this. Do you know if it works?

edit: I am a fool, you haven't tested it yet.

Indeed, I haven't tested it yet. I have ordered prototype boards for rev 0 (not the latest rev B; I accidentally sent the wrong gerbers to the manufacturer )). There are only small differences between revisions, so if rev 0 works I'm 90% sure rev B will too.

After that I'll need to order components and assemble it and upload a bootloader and stuff before I can do any thorough testing.

But as I said earlier I'm very busy at the moment with work and getting XDA Oblique ready for GB. I'll get around to it eventually though

[ju6ju8Oo]

very cool - love it's open source.

[Lbibass]

I really, really like this! Super excited for this. Do you know if it works?

edit: I am a fool, you haven't tested it yet.

Indeed, I haven't tested it yet. I have ordered prototype boards for rev 0 (not the latest rev B; I accidentally sent the wrong gerbers to the manufacturer )). There are only small differences between revisions, so if rev 0 works I'm 90% sure rev B will too.

After that I'll need to order components and assemble it and upload a bootloader and stuff before I can do any thorough testing.

But as I said earlier I'm very busy at the moment with work and getting XDA Oblique ready for GB. I'll get around to it eventually though

Man, that XDA Oblique looks really awesome! I'm actually typing this on a 60% aek right now! I really like that set, can't wait!

[meanagray]

Yes please. ALso are you considering support for all variants of type-c because Macbooks have certain issues with resistance on data lines.

[AuthenticDanger]

Any room for a reset button?

[ju6ju8Oo]

Any room for a reset button?

second this! it will be very useful

[clee]

I would buy the **** out of this. I'd order at least a dozen.

[ju6ju8Oo]

Is there a Gerber file that includes max number of goldfishes  in 100 x 100mm?

[donut_sauce]

this looks awesome!

[ju6ju8Oo]

which version of ATMEGA32U4 should I get? Is it ATMEGA32U4-MU?
And what other components?

[dr_derivative]

Yes please. ALso are you considering support for all variants of type-c because Macbooks have certain issues with resistance on data lines.

I'm following the standard way of wiring up a USB-C port for a USB-2.0 upstream facing port. This is the first I've heard of MacBooks having issues with USB-C, do you have a source? I'd assume any issues have to do with USB 3.0 or 3.1 or another protocol over USB-C, or potentially even USB-C cables? USB 2.0 is such a simple protocol in comparison, so I think it should work on a MacBook if it also works on other devices

Any room for a reset button?

I don't think so, the board is pretty much full with the larger USB-C connector and the extra pins. A button is a pretty big component too when compared with the size of the board and goes against the whole 'super thin' selling point. Many keyboard PCBs that use Pro Micros have a reset button on the PCB anyway.

Is there a Gerber file that includes max number of goldfishes  in 100 x 100mm?

I don't have one since PCBWay doesn't require one, so you'll have to make your own if you need it.

which version of ATMEGA32U4 should I get? Is it ATMEGA32U4-MU?
And what other components?

Yep, it's an ATMEGA32U4-MU, just make sure not to get the RC version since they are configured to use an internal RC oscillator rather than the crystal on the board.

Here's a quick BOM:

Designator	Package	Value
C1-C5,C10	0402	0u1
C6	0603	4u7
C7,C8	0402	22p
C9	0402	1u
J1	Hirose CX70M-24P1
R1,R2	0402	5k1
R3	0402	10k
R4,R5	0402	22R
U1	QFN-44-EP	ATmega32U4-MU
X1	Epson_FA238	16MHz 18pF
D1	PowerDI-123	Schottky

[ju6ju8Oo]

Here's a quick BOM:

Designator	Package	Value
C1-C5,C10	0402	0u1
C6	0603	4u7
C7,C8	0402	22p
C9	0402	1u
J1	Hirose CX70M-24P1
R1,R2	0402	5k1
R3	0402	10k
R4,R5	0402	22R
U1	QFN-44-EP	ATmega32U4-MU
X1	Epson_FA238	16MHz 18pF
D1	PowerDI-123	Schottky

is this for rev B? Any plans for extra components in future ver? I want to grab those components in 1 shipment

[dr_derivative]

Here's a quick BOM:

Designator	Package	Value
C1-C5,C10	0402	0u1
C6	0603	4u7
C7,C8	0402	22p
C9	0402	1u
J1	Hirose CX70M-24P1
R1,R2	0402	5k1
R3	0402	10k
R4,R5	0402	22R
U1	QFN-44-EP	ATmega32U4-MU
X1	Epson_FA238	16MHz 18pF
D1	PowerDI-123	Schottky

is this for rev B? Any plans for extra components in future ver? I want to grab those components in 1 shipment

Yep, that's rev B. I have no planned future revisions at the moment, unless rev B doesn't work ).

[ju6ju8Oo]

Are there any alternatives usb type-c connector?

[concinnus]

Are there any alternatives usb type-c connector?

The type-C connector is this project's whole raison d'être.  There's plenty of pro-micro/clones with micro-B connectors.  If you need more pins, get a Teensy.

But anyway, USB-C is the future, maaan, and all you need for compatibility is an A-to-C cable.  The actual protocol is still USB 2.0, I think.

[iaso]

I made this BOM at Mouser. Could somebody be so kind to verify?

[ju6ju8Oo]

Are there any alternatives usb type-c connector?

The type-C connector is this project's whole raison d'être.  There's plenty of pro-micro/clones with micro-B connectors.  If you need more pins, get a Teensy.

But anyway, USB-C is the future, maaan, and all you need for compatibility is an A-to-C cable.  The actual protocol is still USB 2.0, I think.

sorry i wasn't clear. I mean if there're other type-c connectors that are recommended because the default one is hard to source for me

[ju6ju8Oo]

Will c-c cables work?

[concinnus]

It should be equivalent to connecting a micro/mini-B keyboard to a USB-C platform (for which cables exist), so I see no reason it shouldn't.

[voight-kampff]

Great, cant wait for this

Please add a third eye for the goldfish, also because it is usb 3

[concinnus]

Except it's USB 2.0

[FSund]

Just found this thread via a Google search, and found it very interesting. Any progress?

Is it feasible to order a fully assembled Goldfish in low volumes for a reasonable price, or will that end up crazy expensive?
I do not have the equipment to solder all those tiny components, so a fully assembled one would be best.

[mrbishop]

when's the prototypes coming in?

this needs to be a thing! i know of several stores that would carry this.

[xack]

yep i would totally use that over anything other 
Is this still under development?

[bakageta]

Any updates on testing, or has this been back-burnered? I may get a batch of these produced myself to test, they'd go great with a project I'm working on.

[dr_derivative]

Sorry about the lack of updates on this project in the last half year, it's sort of fallen by the wayside for me. I always intended to work on this some more, but as time went on I just kinda lost interest in this project

I know a lot of people have been asking about a groupbuy for this board, but since way cooler projects like the QMK Proton C are just around the corner I don't see much of a place for this in the market any more. On top of that, to be able achieve a reasonable price/unit in a GB, we'd need to sell a lot of these. This means I'd have to QC and flash bootloaders for all those boards or find a factory to do that for me on top of all the usual organisation that goes into a groupbuy, and at the moment that's not something I see myself doing.

That being said, the design is open source for a reason. If anyone else wants to put in the work to develop it further or run a groupbuy or whatever, feel free.

[Findecanor]

Since this project hasn't had a group buy, I hope you don't mind me posting this other board that does the same thing (for those who had this thread on their watch-list): Elite-C.

It is not as low-profile as the Goldfish (different USB-C connector) but it also exposes more ATmega32U4 pins on the short edge (two of which are mapped the same as Goldfish) and D+/D- (for USB breakout board), and it has a reset switch.
It has the RAW pin remapped as B0 however, so it would be incompatible with any mother-PCB which relies on it for power (but there shouldn't be any...).

[equalunique]

Nice to know there is an open source alternative to the Elite-C

[piit79]

Since this project is apparently shut down, I hope you don't mind me posting this other board that does the same thing (for those who had this thread on their watch-list): Elite-C.

The Elite-C is nice, I got a couple for my Quefrency. I just wish it was cheaper - $18 _on sale_ seems overpriced. It's even more expensive than the QMK Proton C which has STM32... (Although not available nearly anywhere atm.)

I might look into having a few of these made,get them priced and perhaps try an IC.

Sent from my OnePlus 6T with a rubbish gimmicky bloody annoying unreliable in-display fingerprint reader using Tapatalk

[dr_derivative]

Since this project is apparently shut down, I hope you don't mind me posting this other board that does the same thing (for those who had this thread on their watch-list): Elite-C.

The Elite-C is nice, I got a couple for my Quefrency. I just wish it was cheaper - $18 _on sale_ seems overpriced. It's even more expensive than the QMK Proton C which has STM32... (Although not available nearly anywhere atm.)

I might look into having a few of these made,get them priced and perhaps try an IC.

Sent from my OnePlus 6T with a rubbish gimmicky bloody annoying unreliable in-display fingerprint reader using Tapatalk

IIRC I did some back-of-the-envelope calculations back when I was working on this and if you hit high enough MOQs the manufacturing cost should be around $8-$10 (don't quote me on that though). If you're serious about running a GB I can have a look at changing the pinout at the bottom to match the Elite-C if I have time.

Just bear in mind that I haven't done any prototyping or testing on this board; I didn't want to spend money on a project I wasn't really interested in any more. So test it first before running a big GB

[piit79]

IIRC I did some back-of-the-envelope calculations back when I was working on this and if you hit high enough MOQs the manufacturing cost should be around $8-$10 (don't quote me on that though). If you're serious about running a GB I can have a look at changing the pinout at the bottom to match the Elite-C if I have time.

Just bear in mind that I haven't done any prototyping or testing on this board; I didn't want to spend money on a project I wasn't really interested in any more. So test it first before running a big GB

Thanks for the reply! That would be great. I'm generally profficient in electronics but I haven't done any PCB prototyping yet so would appreciate any help you could provide.

I'd love to run the GB - if there's still interest of course. Trouble is I'm in EU and the vast majority of the mk scene seems to be in the US, so not sure how many orders I could get. Plus PCB manufacturing is probably more expensive here. Will see about that.

Sent from my OnePlus 6T with a rubbish gimmicky bloody annoying unreliable in-display fingerprint reader using Tapatalk