Hacking Hardware McFly - an RP2040 board compatible with Picofly

jkyoho · Mar 24, 2023

CPU and RAM edge to edge is about 10.4mm. Max top to bottom inside shield is around 32.6mm. Depth under the shield cover about 1.5mm

Saliciae · Mar 24, 2023

CPU and RAM edge to edge is about 10.4mm. Max top to bottom inside shield is around 32.6mm. Depth under the shield cover about 1.5mm

jkyoho said:
View attachment 360962

I think i can make this work ngl, although the bit that covers the area will probably need snipping out

Tailsy · Mar 24, 2023

@Saliciae Thanks for sharing the board, seems very nice. Looking at it I've got 2 concerns (which even encouraged me to register, so hello

).
First concern is clearance to board outlines. It seems to me that at least 3 traces (2 on the left of flash chip, one around xtal) seem to be very close to board edge. Several (cheap) manufactures have some pretty limiting rules (especially if you want to panel with v-cuts), like 0.5mm clearance required. What is clearance in your board? Seems very tight, but hard to judge based on screenshots.

Second concern is about usb-board getting considered as a second design, significantly increasing price. Boards are connected by wires, but they seem like a 2 different ones separated by drill holes. Even if your current test-design was not extra charged, I would think of this becoming a problem the more people start ordering the boards. Or maybe I'm completely wrong here and extra charge only count for panelized boards.

Regarding panelizing, I would suggest to align the 2 boards to each other, unless you have functional reason to keep current shape. In attachment is what I mind, excuse my crude paint job

. Such a shape would make the board MUCH easier to manufacture, panelize and thus possibly cheaper. White lines indicate v-cuts in panel.

I would like to strongly encourage you to create a github repository with your board file(s), even if they're not finished. It would be easier for many people to suggest improvements and double-check for issues.

Cheers

Saliciae · Mar 24, 2023

Tailsy said:
@Saliciae Thanks for sharing the board, seems very nice. Looking at it I've got 2 concerns (which even encouraged me to register, so hello ).
First concern is clearance to board outlines. It seems to me that at least 3 traces (2 on the left of flash chip, one around xtal) seem to be very close to board edge. Several (cheap) manufactures have some pretty limiting rules (especially if you want to panel with v-cuts), like 0.5mm clearance required. What is clearance in your board? Seems very tight, but hard to judge based on screenshots.

Second concern is about usb-board getting considered as a second design, significantly increasing price. Boards are connected by wires, but they seem like a 2 different ones separated by drill holes. Even if your current test-design was not extra charged, I would think of this becoming a problem the more people start ordering the boards. Or maybe I'm completely wrong here and extra charge only count for panelized boards.

Regarding panelizing, I would suggest to align the 2 boards to each other, unless you have functional reason to keep current shape. In attachment is what I mind, excuse my crude paint job . Such a shape would make the board MUCH easier to manufacture, panelize and thus possibly cheaper. White lines indicate v-cuts in panel.

I would like to strongly encourage you to create a github repository with your board file(s), even if they're not finished. It would be easier for many people to suggest improvements and double-check for issues.

Cheers

Hi, thanks for the feedback, those do make sense, ngl i wanted the usb board to be symmetrical for looks haha. I can definitely move it over though

Also I can confirm jlcpcb don't seem to care about the clearance or the snap off section, all 5 pcbs were 18 bucks total in 0.6mm fr4 (extra cost was in ENIG finishing). there's 5 mils of clearance edge to trace, which is definitely tight, but hopefully it's ok.

whilst i can understand the reasoning I'm not gonna publish unfinished files, I dont want potentially unfinished and untested files floating around the internet, especially in the event the GitHub repo goes down for some reason

rehius · Mar 24, 2023

Saliciae said:
although the bit that covers the area will probably need snipping out

no, if you face all the components down. even LED - its reflection could be easily seen if placed close to the right side

Saliciae · Mar 24, 2023

rehius said:
no, if you face all the components down. even LED - its reflection could be easily seen if placed close to the right side

My concern is more getting the pcb in that space, expecially if the flex is integrated

I really want to try this though, when i get some more money i might pick up a lite and use that to develop this

Dee87 · Mar 24, 2023

Saliciae said:
My concern is more getting the pcb in that space, expecially if the flex is integrated

I really want to try this though, when i get some more money i might pick up a lite and use that to develop this

Saliciae said:

My concern is more getting the pcb in that space, expecially if the flex is integrated

I really want to try this though, when i get some more money i might pick up a lite and use that to develop this

Click to expand...

if u need a board i can send u one ? just hit me up with a pm i could possible send u a whole v2 with a defektive board but i would need everything back if u would consider this hit me up with a pm. my concerns are it prob gonna cost tax since ur not in the eu anymore Xd

Saliciae · Mar 24, 2023

thanks for the offer but tbh it's probably cheaper for me to hit up facebook marketplace or something, seen slightly broken but repairable ones going pretty cheap, just need to keep my eye out for the right deal. a working one will let me see if my creations actually work too

Tailsy · Mar 24, 2023

Saliciae said:
Hi, thanks for the feedback, those do make sense, ngl i wanted the usb board to be symmetrical for looks haha. I can definitely move it over though

Also I can confirm jlcpcb don't seem to care about the clearance or the snap off section, all 5 pcbs were 18 bucks total in 0.6mm fr4 (extra cost was in ENIG finishing). there's 5 mils of clearance edge to trace, which is definitely tight, but hopefully it's ok.

whilst i can understand the reasoning I'm not gonna publish unfinished files, I dont want potentially unfinished and untested files floating around the internet, especially in the event the GitHub repo goes down for some reason

5 mils=0.127mm is less than required JLCPCB 0.2mm Trace to Outline limit, and much less that 0.4mm if you need v-cuts (for panelizing later). If it made it through, it's probably because you've chosen expensive ENIG finish, so they're less forgiving. I would definitely fix that, even though it's kind of painful

BTW: for what is the 2pin through-hole connector?

Saliciae · Mar 24, 2023

Tailsy said:
5 mils=0.127mm is less than required JLCPCB 0.2mm Trace to Outline limit, and much less that 0.4mm if you need v-cuts (for panelizing later). If it made it through, it's probably because you've chosen expensive ENIG finish, so they're less forgiving. I would definitely fix that, even though it's kind of painful

BTW: for what is the 2pin through-hole connector?

oh oops lol, i'll fix that, need to get proper design rules implemented in the kicad project

2 pin is a jumper that breaks out gpio1

Tailsy · Mar 24, 2023

Saliciae said:
oh oops lol, i'll fix that, need to get proper design rules implemented in the kicad project

2 pin is a jumper that can be shorted with tweezers to reset the glitch training .The solder jumper on the bottom is to switch the rgb led mode, but i'm gonna remove that once i know the colour mapping on the LEDs i'm using

If the jumper can be covered during programming, you can consider saving even more space by putting the 5-pin connector inside of the USB board, which would make it rectangle and look less separated from the main board. But this is only when we consider protruding connector as non-important.

Saliciae · Mar 24, 2023

i think it's better for it to be protruding, to make it easier to align and connect it when reprogramming

gokuz · Mar 24, 2023

Saliciae said:
My concern is more getting the pcb in that space, expecially if the flex is integrated

I really want to try this though, when i get some more money i might pick up a lite and use that to develop this

Did you populate the total parts necessary, resistors/caps? Or you just desolder and salvage parts from rp2040 zero? I imagine that would be difficult to do

BigHorse420 · Mar 24, 2023

I did a quick overlay of the best erista and mariko pictures I could find, and it seems like it's (barely) possible to make a universal cpu connector for both

gamecartgirl · Mar 24, 2023

Saliciae said:
Introducing the Mcfly, a barebones RP2040 board designed from the ground up to be compact, simple and slim. With a USB port that breaks away after initial programming the overall thickness of the board can be reduced to ~2mm. An X and Y footprint of ~19x19mm makes this stripped back board suitable for internal installation in the switch. No stone was left unturned in the design of this board, with all the features of a conventional picofly install present including the debug WS2812 LED and the jumper to reset the glitch timings as well as the inclusion of a 6 pin fpc connector designed to be used with HWFLY CPU flex cables, simplifying the installation and reducing the risk of damaging the APU. Despite the breakaway connector the Mcfly can be updated too, using a 5 pin 1.27mm header the usb section can be either temporarily soldered back on, or a pin header attached and it held in place whilst the board is reprogrammed.

View attachment 360663 View attachment 360665

Upon completion of testing the Mcfly will be released under the Creative Commons Attribution Share Alike licence, opening the door for design improvements and alterations by the community, as well as commercialisation by a third party, at this moment i do not plan to commercialise this design myself, I simply dont have the time to sell these personally. If you would be interested in selling these or know someone who is please get in touch! This wont be price competitive with a 2040-Zero, in low quantities that's simply not possible, nor will it be as easy to install as the inevitable HwFly picofly board. The goal is for this to be a community driven open source solution that simplifies the install to the greatest extent possible whilst still being reasonably low cost, using off the shelf parts you can get from any component retailer
View attachment 360664
As it stands the hardware layout is largely complete for now, pending feedback from testers, components have been ordered and the PCBs have also been ordered. I should recieve them in a week ish and can build a few.

I cannot make this a reality without your help, i'm currently looking for testers able to give this a go and provide feedback, my switch is an unpatched erista and i cant afford to buy another just for this project. Testers should be experienced with the switch, done several installations of other modchips and be willing to provide useful critical feedback to improve the design. If you have a HWFLY cpu cable to try with my board that would be even better as i have no idea if i've implemented that properly tbh. Please DM me if you're serious about testing this.

If you have any questions or feedback ask away!

Would one of these be used as an external RCM loader for the original switch?

jkyoho · Mar 24, 2023

BigHorse420 said:
I did a quick overlay of the best erista and mariko pictures I could find, and it seems like it's (barely) possible to make a universal cpu connector for both

L shape solder pad should fit both version TEGRA CPU CAP

impeeza · Mar 24, 2023

Saliciae said:
Introducing the Mcfly, a barebones RP2040 board designed from the ground up to be compact, simple and slim. With a USB port that breaks away after initial programming the overall thickness of the board can be reduced to ~2mm. An X and Y footprint of ~19x19mm makes this stripped back board suitable for internal installation in the switch. No stone was left unturned in the design of this board, with all the features of a conventional picofly install present including the debug WS2812 LED and the jumper to reset the glitch timings as well as the inclusion of a 6 pin fpc connector designed to be used with HWFLY CPU flex cables, simplifying the installation and reducing the risk of damaging the APU. Despite the breakaway connector the Mcfly can be updated too, using a 5 pin 1.27mm header the usb section can be either temporarily soldered back on, or a pin header attached and it held in place whilst the board is reprogrammed.

View attachment 360663 View attachment 360665

Upon completion of testing the Mcfly will be released under the Creative Commons Attribution Share Alike licence, opening the door for design improvements and alterations by the community, as well as commercialisation by a third party, at this moment i do not plan to commercialise this design myself, I simply dont have the time to sell these personally. If you would be interested in selling these or know someone who is please get in touch! This wont be price competitive with a 2040-Zero, in low quantities that's simply not possible, nor will it be as easy to install as the inevitable HwFly picofly board. The goal is for this to be a community driven open source solution that simplifies the install to the greatest extent possible whilst still being reasonably low cost, using off the shelf parts you can get from any component retailer
View attachment 360664
As it stands the hardware layout is largely complete for now, pending feedback from testers, components have been ordered and the PCBs have also been ordered. I should recieve them in a week ish and can build a few.

I cannot make this a reality without your help, i'm currently looking for testers able to give this a go and provide feedback, my switch is an unpatched erista and i cant afford to buy another just for this project. Testers should be experienced with the switch, done several installations of other modchips and be willing to provide useful critical feedback to improve the design. If you have a HWFLY cpu cable to try with my board that would be even better as i have no idea if i've implemented that properly tbh. Please DM me if you're serious about testing this.

If you have any questions or feedback ask away!

how can I invest on the production! this is the great idea of last year!

Saliciae · Mar 24, 2023

gokuz said:
Did you populate the total parts necessary, resistors/caps? Or you just desolder and salvage parts from rp2040 zero? I imagine that would be difficult to do

Board needs components that aren't present on rp2040-zero, everything except the rp2040 microcontroller itself can be bought off lcsc

gamecartgirl said:
Would one of these be used as an external RCM loader for the original switch?

No, this could be used as an internal glitcher chip for homebrew on patched erista and mariko

impeeza said:
how can I invest on the production! this is the great idea of last year!

I'm not gonna be producing these, I dont want to deal with that stuff, board files will be released once complete and anyyone can order from jlc and lcsc and build it themselves

Tailsy · Mar 24, 2023

@Saliciae I just spotted a different issue with your board, you seem to use microvias or just very small, typical vias. I see also vias in pads. This stuff is very expensive to produce and out of question for hobby boards. Min via drill size for JLCPCB is 0.3mm with 0.6mm diameter. You really need to adjust limits in kicad and disable microvias.

Saliciae · Mar 24, 2023

Tailsy said:
@Saliciae I just spotted a different issue with your board, you seem to use microvias or just very small, typical vias. I see also vias in pads. This stuff is very expensive to produce and out of question for hobby boards. Min via drill size for JLCPCB is 0.3mm with 0.6mm diameter. You really need to adjust limits in kicad and disable microvias.

I didn't use microvias, i used 0.3/0.5 vias which jlcpcb allows in their capabilities. vias in pads are fine but wont be filled. neither are major issues

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