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

[dr_derivative]

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

I'm afraid I can't help much with the GB since I'm EU too.

If you want to chat about the board feel free to PM me on Discord, my name is in my signature.

[ju6ju8Oo]

Is the rev C production ready?

[dr_derivative]

Is the rev C production ready?

I don't think anyone has tested Rev. C, but it should be OK.

 The only major change from Rev. B is that the pins at the bottom are reordered to match the Elite-C. And I know other people have used Rev. B without problems.

[ju6ju8Oo]

I want to give it a try. Any tutorial for hand soldering the goldfish? I’m a complete newbie in SMT soldering

[dr_derivative]

There's nothing specific for the Goldfish, but there are lots of SMT soldering guides and stuff on youtube if you search for it.

[ju6ju8Oo]

How does goldfish compare to elite C, other than the mid mount type C?

[Findecanor]

* The Elite-C repurposes the RAW pin for PB0, which makes it incompatible with a couple of keyboard PCBs out there that expect it to be VBUS power. Goldfish does not.
* It has a physical reset switch, which is almost as thick as the USB-Type C port. Goldfish is thinner here.
* Has a power LED like the Pro Micro (Version 2 onwards). Goldfish has no LED.
* The current version: version 3, has a bug that makes auto-detection of Master/Slave on split keyboards not work. Previous versions worked, and the bug is supposed to be fixed in version 4. (Edit: Fixed in version 3.1)
Goldfish should support this auto-detection with revision B onwards.

[ErgoMacros]

Re:Soldering...
There are also a lot of SMT practice boards at Amazon and eBay. Couple buck a piece.

[ctrlshiftba]

* The current version: version 3, has a bug that makes auto-detection of Master/Slave on split keyboards not work. Previous versions worked, and the bug is supposed to be fixed in version 4.
Goldfish should support this auto-detection with revision B onwards.

They mentioned on off the clack they did find a software fix for this. Not sure if you need a branch of QMK or it’s in master.

[ju6ju8Oo]

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

Show Image

the number of 0u1 should be 6?

[Findecanor]

They mentioned on off the clack they did find a software fix for this.

It's a workaround, not a fix. The workaround disables suspend-mode, and a USB device that does not suspend is not USB compliant.

[ju6ju8Oo]

The schematic is referencing goldfish-rescue. But it's not included in the repo. 

[ju6ju8Oo]

Do I need a hot air gun for the atmega32U4 QFN? Or is it easier to switch it to QFP?

[yui]

in theory you could reflow it in a toaster oven, i never tried but there is quite a few videos of peoples doing it successfully (i would try on cheaper components 1st), and the very cheap e-bay hot air guns have some issues with temperatures and mine had it's heater filament melt at a weak spot and some peoples also manage to do it with soldering irons. so depending on budget and if you already have the controller you could go that route, if you do not the QFP should be easier but you should check if it is compatible, with it being wider than QFN.

[dr_derivative]

The schematic is referencing goldfish-rescue. But it's not included in the repo. 

Sorry about that, I just pushed a fix

Do I need a hot air gun for the atmega32U4 QFN? Or is it easier to switch it to QFP?

QFP won't work because it's quite a bit bigger than the QFN.

With some patience and a lot of flux you should be able to solder the QFN with a regular iron. You can look up videos of drag soldering if you're unsure of the technique.

The only exception is the grounding pad on the bottom, but you can get away with leaving it disconnected. There's plenty of other ground pins and an atmega is never going to generate enough heat to really need thermal relief. If I were running a GB or something I'd make sure they were connected properly of course, but I've always done it this way for prototyping and never had any problems.

[ju6ju8Oo]

first time making the BOM list..no confidence
please give me some feedback on the BOM list. thank you!!

Samsung   CL05B104KO5NNNC
Samsung   CL05A475MP5NRNC
Samsung   CL05C220JB5NNNC
Samsung   CL05A105KQ5NNNC
UNIOHM   0402WGF5101TCE
UNIOHM   0402WGF1002TCE
UNIOHM   0402WGF220JTCE
Schottky   DFLS1100Q-7
Microchip   ATMEGA32U-MU
Epson Timing      FA-238 16.0000MB-C3
Hirose   CX70M-24P1

[dr_derivative]

first time making the BOM list..no confidence
please give me some feedback on the BOM list. thank you!!

Samsung   CL05B104KO5NNNC
Samsung   CL05A475MP5NRNC
Samsung   CL05C220JB5NNNC
Samsung   CL05A105KQ5NNNC
UNIOHM   0402WGF5101TCE
UNIOHM   0402WGF1002TCE
UNIOHM   0402WGF220JTCE
Schottky   DFLS1100Q-7
Microchip   ATMEGA32U-MU
Epson Timing      FA-238 16.0000MB-C3
Hirose   CX70M-24P1

Looks good to me

[Findecanor]

... atmega is never going to generate enough heat to really need thermal relief.

BTW. I noticed on the Teensy 2.0 that there is a ground pad on the bottom with 16 vias spaced in a grid connecting it to the top under the µC. I suppose that was meant for cooling, but maybe it is superfluous.

[vvp]

BTW. I noticed on the Teensy 2.0 that there is a ground pad on the bottom with 16 vias spaced in a grid connecting it to the top under the µC. I suppose that was meant for cooling, but maybe it is superfluous.

Maybe it was meant to allow soldering with iron (instead of hot air or oven). I have seen a video of heating the centre pad from the other side of PCB. The idea was that heat will travel  through vias to the centre pad. I did not try it myself though. I tried other approach: I placed a "huge" through hole pad under the QFN centre pad so that I can reach to it directly from the other side (using a tip thin enough to fit into the through hole pad).

[dr_derivative]

... atmega is never going to generate enough heat to really need thermal relief.

BTW. I noticed on the Teensy 2.0 that there is a ground pad on the bottom with 16 vias spaced in a grid connecting it to the top under the µC. I suppose that was meant for cooling, but maybe it is superfluous.

Yeah, it's definitely superfluous for an atmega. Other chips using the same package could need it though. The designer of the teensy might well have used a standard footprint which included those vias.

BTW. I noticed on the Teensy 2.0 that there is a ground pad on the bottom with 16 vias spaced in a grid connecting it to the top under the µC. I suppose that was meant for cooling, but maybe it is superfluous.

Maybe it was meant to allow soldering with iron (instead of hot air or oven). I have seen a video of heating the centre pad from the other side of PCB. The idea was that heat will travel  through vias to the centre pad. I did not try it myself though. I tried other approach: I placed a "huge" through hole pad under the QFN centre pad so that I can reach to it directly from the other side (using a tip thin enough to fit into the through hole pad).

I've seen both those approaches before too, I should try them some time. How well did the big through hole pad work for you?

[hanya]

Hirose CX70M-24P1 USB Type-C connector could be replaced by Hirose CX90M-16P.
CX90M-16P does not have TX and RX pins that USB 2.0 does not require. And also no through hole pins, wider pin pitch.
Less pins helps you to decrease manufacturing cost too.

[dr_derivative]

Hirose CX70M-24P1 USB Type-C connector could be replaced by Hirose CX90M-16P.
CX90M-16P does not have TX and RX pins that USB 2.0 does not require. And also no through hole pins, wider pin pitch.
Less pins helps you to decrease manufacturing cost too.

Yeah, I definitely could. When I designed this nearly 2 years ago the only type-C port without USB 3.0 pins was the HRO Type-C-31-M-12 which isn't mid mount. I know there are way more options now. If I get some time I might have a look at what's available to replace the current connector.

The only issue I have with the CX90M-16P is that it doesn't sit low enough in the PCB. With a ~1.6mm PCB the CX70 is almost exactly centred while the CX90 sticks out way more on top.

[ju6ju8Oo]

Which soldering tip do you recommend for the usb c connector?
I have a T12-BC2 but it might be too big.

[dr_derivative]

Which soldering tip do you recommend for the usb c connector?
I have a T12-BC2 but it might be too big.

That tip should be fine. You can use the same drag soldering technique as for the microcontroller and it should be fine. For the through hole pins on the back I'd use a similar technique too, just be careful not to accidentally bridge the pads since they are very close.

[TheOneNight...Post?]

Hello!
I came here from google, I like how small this board is and that itll not be that expensive at the quantity I want to make (like 10), but before I go ahead and buy all the components (kinda sad that its not for sale), one thing is bugging me: How did you solder the through hole parts of the connector to 1.6 mm FR4? The pins looked really short to me, so I downloaded the STEP files and measured only 0.33 mm between the SMD pin bottom and the bottom of the pins... The Hirose website says max PCB thickness is 0.8 mm, so how does that work? 

I would highly appreciate any photos of finished ones... Pretty sure the pins dont reach the other side! Sorry for the trouble...

[dr_derivative]

Hello!
I came here from google, I like how small this board is and that itll not be that expensive at the quantity I want to make (like 10), but before I go ahead and buy all the components (kinda sad that its not for sale), one thing is bugging me: How did you solder the through hole parts of the connector to 1.6 mm FR4? The pins looked really short to me, so I downloaded the STEP files and measured only 0.33 mm between the SMD pin bottom and the bottom of the pins... The Hirose website says max PCB thickness is 0.8 mm, so how does that work? 

I would highly appreciate any photos of finished ones... Pretty sure the pins dont reach the other side! Sorry for the trouble...

You're right, the pins don't reach the other side with a 1.6mm PCB. If you solder the pins the surface tension will pull the solder into the hole (look up capillary effect) to make contact with the pin. This also happens with normal through-hole soldering; the solder will flow all the way through the hole to the other side.

Otherwise, if you'd prefer, there's no reason why you can't use an 0.8mm PCB. There really is no reason why you'd have to stick with the standard 1.6mm for this board

[TheOneNight...Post?]

Yeah, I do know that solder will in fact wick and will reach them. But is that good practice? I already ordered everything, just curious at this point.

[dr_derivative]

Yeah, I do know that solder will in fact wick and will reach them. But is that good practice? I already ordered everything, just curious at this point.

Probably not if you're assembling them by machine. You might end up with some bad joints and they'll be more difficult to inspect and stuff.

But in this case for manual assembly; if it works, it works ¯\_(ツ)_/¯

[equalunique]

On twitter I saw this "ShiroMicro UZU Edition" microcontroller that looks similar to Goldfish: https://twitter.com/elfmimi/status/1200590989267623936?s=19

Sent from my Ono-Sendai Cyberspace 7 using Tapatalk

[Findecanor]

I checked the ShiroMicro's schema yesterday. It's pretty basic in comparison. It has a diode for master/slave detection and a mid-mounted port. No additional pins, no voltage regulator, no LEDs and no over-current protection. Edit: There is a fuse. Sorry!
One interesting detail though: to enable the RAW pin, you'd need to bridge a solder-jumper which shorts it to VBUS. Another jumper shorts PD6 to ground - for hard master/slave assignment maybe?

BTW. The red "Uzu edition" is for the Uzu42 keyboard. The designer has also shown a ARM-based Pro Micro clone.

[ju6ju8Oo]

Hirose CX70M-24P1 USB Type-C connector could be replaced by Hirose CX90M-16P.
CX90M-16P does not have TX and RX pins that USB 2.0 does not require. And also no through hole pins, wider pin pitch.
Less pins helps you to decrease manufacturing cost too.

second this! single side SMT would decrease the cost!

[ju6ju8Oo]

I checked the ShiroMicro's schema yesterday. It's pretty basic in comparison. It has a diode for master/slave detection and a mid-mounted port. No additional pins, no voltage regulator, no LEDs and no over-current protection.
One interesting detail though: to enable the RAW pin, you'd need to bridge a solder-jumper which shorts it to VBUS. Another jumper shorts PD6 to ground - for hard master/slave assignment maybe?

BTW. The red "Uzu edition" is for the Uzu42 keyboard. The designer has also shown a ARM-based Pro Micro clone.

The ShiroMicro's type C mount looks interesting too.

[ju6ju8Oo]

Is there a way to test if the goldfish is fully working? Maybe I should write a small arduino program to test each pin? or does it already exist?

[dr_derivative]

Is there a way to test if the goldfish is fully working? Maybe I should write a small arduino program to test each pin? or does it already exist?

I haven't written any program like that, but it shouldn't be very difficult to do something like that in Arduino.

[ju6ju8Oo]

Another newbie question, what are the benefits of using a PowerDI123 verses 1N5819 sod-123?

[dr_derivative]

Another newbie question, what are the benefits of using a PowerDI123 verses 1N5819 sod-123?

There aren't really any benefits in this case, I just happened to have a bunch of powerdi123 Schottkies lying around when I originally designed the board

In general, PowerDI-123 is designed for better heat dissipation than a regular SOD-123 package. It has a much bigger pad on the cathode pin to transfer heat to the PCB more effectively.

[ju6ju8Oo]

no over-current protection.

It looks like there's a fuse in ShiroMicro. Or is it something different?

[Findecanor]

no over-current protection.

It looks like there's a fuse in ShiroMicro. Or is it something different?

You're right. My bad. The symbol looked too much like a resistor's.

[DevilZmods]

I'm looking to order a whole bunch of PCBs and components for these. Anything I need to watch out for?

[DevilZmods]

Also, (excuse the double post, hope this isn't considered a double necro)
LCSC seems to have a connector with identical footprint to the hirose cx70 one. i ordered a few and will check if they fit.
https://lcsc.com/product-detail/USB-Connectors_Jing-Extension-of-the-Electronic-Co-C168695_C168695.html

[The_Ginger]

I'm looking to order a whole bunch of PCBs and components for these. Anything I need to watch out for?

I wanted to make this pcb too in a couple weeks or months. Would you like to post your BOM and if you finish it how the soldering/construction of the pcb went?

[DevilZmods]

I'll definitely keep you updated. I got about 35 PCBs of varying thickness but only 10 sets of components because expensive.
Also because the hirose type c connectors are out of stock on mouser.de and I didn't want to order them in bulk from a more expensive source.

[DevilZmods]

Ok, so the PCBs came in and the clone connector I linked above sits perfectly. That means you can order all components from lcsc and don't have to go hunting for the specific hirose model.

Progress report:
I missed some components when ordering, so I'll add a full list of components for the revision C later. The 0603 footprint for C6 has also been changed back to an 0402.

Also I should've gotten a stencil with the PCBs and some solder paste.

[therealding]

What PCB thickness did u choose? And I'm guessing you ordered from JLCPcb?

[DevilZmods]

I actually ordered both 1.6mm thickness and 1.2mm PCBs. 1.2 should be absolutely fine, and if you go thinner, that might even help when soldering the connector in place. (It has six through hole pins begind the flat legs you can see from the top, so you can't reach those with a soldering iron from the top)
I'd still recommend a hot air station though.

[therealding]

Alright thanks for the reply! I did pick up a hot air station recently but I felt I wasn't experienced enough so I ended up modifying the ShiroMicro PCB design to include the extra pins that the Goldfish design has since the TQFP is easier to solder than QFN

[d3vastat0r]

Ok, so the PCBs came in and the clone connector I linked above sits perfectly. That means you can order all components from lcsc and don't have to go hunting for the specific hirose model.

Show Image

Progress report:
I missed some components when ordering, so I'll add a full list of components for the revision C later. The 0603 footprint for C6 has also been changed back to an 0402.

Also I should've gotten a stencil with the PCBs and some solder paste.

So, do we have a success story?

[DevilZmods]

Not yet. In the meantime i got a hot air station and some solder paste in, but i didn't order the missing components yet. I'm fairly confident with electronics, but navigating lcsc and ordering surface mount components just makes me want to smash my head on the table.

[d3vastat0r]

oh, sorry to hear that. Have you seen tzarc's Djinn? It has a whole LCSC BOM, maybe that might help inspire you.

[DevilZmods]

Ordered the missing components because i needed some mosfets anyways. luckily i took notes before i abanded the project a few months ago. 

[piit79]

Ordered the missing components because i needed some mosfets anyways. luckily i took notes before i abanded the project a few months ago. 

Just got back to this thread after almost two years, because Elite-C expensive... I also found the alternative connector at LCSC, it's great that you confirmed that it works correctly. I'm a bit uneasy about the low stock (only 35 atm) - hope it's not discontinued. I want to see how much will LSCPCB assembly cost, I would eventually like to order ~50-100 for my little on-line shop I started in December. I offer good value through-hole kits and also Pro Micro based kits, so having a cheaper controller module with USB-C would be great.

Do you have a BOM at LCSC? I'll be watching with interest, hope you can finish your boards and confirm they work correctly

Thanks!

[DevilZmods]

I'll happily share the exact parts I ordered once can confirm them working

[piit79]

I'll happily share the exact parts I ordered once can confirm them working

That would help a lot, thanks!

[dr_derivative]

I'll happily share the exact parts I ordered once can confirm them working

If you (or anyone else) put together a BOM/other resources let me know and I'll add them to the first post and the readme on Github.

...
I would eventually like to order ~50-100 for my little on-line shop I started in December.
...

Let me know when you start selling them, I'll add a link to your store too.

[tokas]

Had some done via PCB A , still had to solder the USB Connector by hand though
Works very nicely

[cu99]

Ordered the missing components because i needed some mosfets anyways. luckily i took notes before i abanded the project a few months ago. 

Just got back to this thread after almost two years, because Elite-C expensive... I also found the alternative connector at LCSC, it's great that you confirmed that it works correctly. I'm a bit uneasy about the low stock (only 35 atm) - hope it's not discontinued. I want to see how much will LSCPCB assembly cost, I would eventually like to order ~50-100 for my little on-line shop I started in December. I offer good value through-hole kits and also Pro Micro based kits, so having a cheaper controller module with USB-C would be great.

Do you have a BOM at LCSC? I'll be watching with interest, hope you can finish your boards and confirm they work correctly

Thanks!

Where can I buy your version?
is it https://shop.beekeeb.com/product/goldfish-rev-c-open-source-pro-micro-replacement/ or https://shop.tokas.co.uk/product/comet-usb-c-microcontroller ?

[dr_derivative]

Ordered the missing components because i needed some mosfets anyways. luckily i took notes before i abanded the project a few months ago. 

Just got back to this thread after almost two years, because Elite-C expensive... I also found the alternative connector at LCSC, it's great that you confirmed that it works correctly. I'm a bit uneasy about the low stock (only 35 atm) - hope it's not discontinued. I want to see how much will LSCPCB assembly cost, I would eventually like to order ~50-100 for my little on-line shop I started in December. I offer good value through-hole kits and also Pro Micro based kits, so having a cheaper controller module with USB-C would be great.

Do you have a BOM at LCSC? I'll be watching with interest, hope you can finish your boards and confirm they work correctly

Thanks!

Where can I buy your version?
is it https://shop.beekeeb.com/product/goldfish-rev-c-open-source-pro-micro-replacement/ or https://shop.tokas.co.uk/product/comet-usb-c-microcontroller ?

Tokas is selling boards at that second link. It's a modified design with a different USB-C connector.

I had no idea beekeeb is selling goldfish too I have added links to both vendors to the original post and the Github repo.

Everyone, LMK if there are any other Goldfish or derivations for sale that I've missed and I'll add them too

[cu99]

I can add some TVS diodes if transients do end up being a problem, but I doubt it's needed.

Is a TVS diode used for ESD protection?

[cu99]

What's the use of the R6 10k resistor?

[dr_derivative]

What's the use of the R6 10k resistor?

It pulls down VBUS and the UVCC pin when the board is powered by the VCC pin, not through the USB port.

[dr_derivative]

I recently updated the design of Goldfish with a couple changes I had been wanting to make for a long time to create a Golfish v2

I have ordered some prototypes for testing and I will update when those arrive. As before design files and Gerbers are available on the Github repo.

It has the following changes over the previous v1 designs:

• Addition of on board ESD protection and polyfuse
• 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

[piit79]

Great job, thanks for continuing with the project! How is the availability and the price of ATmega32u4 these days? I'm not sure it still makes sense to use it though considering the RP2040 will have official QMK support very soon (or perhaps already has it? Struggling to keep track) and costs $1.30 (plus ~$1 for a QSPI flash)...

[dr_derivative]

Great job, thanks for continuing with the project! How is the availability and the price of ATmega32u4 these days? I'm not sure it still makes sense to use it though considering the RP2040 will have official QMK support very soon (or perhaps already has it? Struggling to keep track) and costs $1.30 (plus ~$1 for a QSPI flash)...

ATmega availability isn't great at the moment unfortunately, it's a big delay for me getting some v2 samples made.

I have thought about making a similar board with a different chip such as the RP2040. That probably would probably use a different name (maybe another kind of fish?) to make the difference clear. It would be cool to have a RPi zero with a Pro Micro footprint and USB-C