Hacking Hardware Picofly - a HWFLY switch modchip

[Blakejansen]

What pico boards can you use for this install? Do you need to desolder USB port still? What resistors are needed? What about the flex?

I think I will switch over to this as I don't want to pay for modchips anymore.

 

[Phantomas77]

What pico boards can you use for this install? Do you need to desolder USB port still? What resistors are needed? What about the flex?

I think I will switch over to this as I don't want to pay for modchips anymore.

There's a great dude named @lightninjay , the answer for all your questions is written in his signature.

 

[Marax]

I really need help.. I resoldered all the wires to the chip this time with the 47 ohms on dat0 and cmd but again first it tries to glitch then it gives 2 short pulse yellow then short break and again 2 short pulse yellow after that nothing. Idk anymore… On RST I get 1600ohms without cable and with cable on the chip I got 800 ohms is this normal?


Now I unsoldered all and she still boots to OFW. Thank god not fried.

 

[Alanamaro]

0201

the board works without

 

[Marax]

I did a video on how the chip behaves I resoldered it now a few times…

He does this since the shutdown with slow mmc….

Edit: I get 260ohms on the RST point with cable connected to chip no Battery. This is not right. What can cause this?
With no wire to the chip it seems normal with 1600ohms... Idk is the chip fried?

 

[Blakejansen]

There's a great dude named @lightninjay , the answer for all your questions is written in his signature.

Since you know the guide so well, what pico would you recommend out of the five that are listed on the guide? The seed XIAO and the Tiny look like the smallest options, but I see that the tiny sometimes comes with the wrong resistors?

Also on the lite install, can you bridge the two pads for each point, or is it one or the other?

 

[Dee87]

Since you know the guide so well, what pico would you recommend out of the five that are listed on the guide? The seed XIAO and the Tiny look like the smallest options, but I see that the tiny sometimes comes with the wrong resistors?

Also on the lite install, can you bridge the two pads for each point, or is it one or the other?

use the tiny but a original one not the clones then the resistors will be correct if u have slow emmc ur gonna have to swap the 47 with 100ohm thats it.

 

[Vigintiduo]

Hey guys, I read a lot about pull-down resistors in this thread.
Rehius himself says that they're not needed, while other guys say they're super important.
So... what's the real answer here?

Up.
Does anyone actually know the answer to this?

 

[Dee87]

Up.
Does anyone actually know the answer to this?

are u talking about them on the mosfet?

i never installed them on over 200 switches and havent had an issue yet but its up to u what u do

 

[Vigintiduo]

are u talking about them on the mosfet?

i never installed them on over 200 switches and havent had an issue yet but its up to u what u do

Yeah, the one between Source and Gate.
I read that rehius made the firmware act as a pull-down, but some guys said you need a 33k resistor, so I was kinda scared

 

[jkyoho]

Yeah, the one between Source and Gate.
I read that rehius made the firmware act as a pull-down, but some guys said you need a 33k resistor, so I was kinda scared

Thats like a airbag on your car. You dont need if you never got into accident

 

[deeps]

Since you know the guide so well, what pico would you recommend out of the five that are listed on the guide? The seed XIAO and the Tiny look like the smallest options, but I see that the tiny sometimes comes with the wrong resistors?

Also on the lite install, can you bridge the two pads for each point, or is it one or the other?

rp2040-tiny pros:
- very thin - no need to remove any on-board components
- resistors preattached
- can be re-flashed via usb even after installation in a switch, since the usb connector does not have to be removed

rp2040-tiny cons:
- clone boards that don't work very well are circulating, must buy directly from waveshare to avoid them
- preattached resistors are 47 ohm - some switches need 100 ohm on dat0/cmd for ofw to work properly
- preattached resistors are very small (0201) and therefore rather difficult to replace
- no obvious space on the board for additional resistors, if replacing the existing ones isn't an option
- slightly more expensive than rp2040-zero

rp2040-zero pros:
- plenty of room for adding rather big (0805) resistors directly on the board without anything sticking out
- very common board, high availability
- slightly cheaper than rp2040-tiny

rp2040-zero cons:
- too thick - need to remove several on-board components with hot air (usb connector, buttons, LDO (optional)) for it to fit in the switch
- no resistors preattached, need to add 100/100/47 ohm for dat0/cmd/clk, preferably 0805 size
- not flashable via usb after installation, since usb connector must be removed. updating via picofly-toolbox works fine though

To summarize, it's a matter of taste. Most people seem to prefer the rp2040-tiny. Both work just fine.

Post automatically merged: Oct 18, 2023

Yeah, the one between Source and Gate.
I read that rehius made the firmware act as a pull-down, but some guys said you need a 33k resistor, so I was kinda scared

The resistor is helpful if the cpu-mosfet cable between chip and mosfet ever gets disconnected while the switch is powered, which will result in the gate point "floating" which might result in the mosfet activating and burning out. As long as you remember to disconnect the battery before installation and don't power up again before the job is done and all points are measured, there's no point in adding a pull-down resistor.

 

[Vigintiduo]

Thats like a airbag on your car. You dont need if you never got into accident

Could you please elaborate further? If the firmware is acting as a pull-down, what would be the case where you would need the resistor?
I'm genuinely asking out of curiosity because I'd like to understand more about that

 

[jkyoho]

Could you please elaborate further? If the firmware is acting as a pull-down, what would be the case where you would need the resistor?
I'm genuinely asking out of curiosity because I'd like to understand more about that

In case you have semi-broken or short to hot line gate wiring inside your device. Or your rp2040 NAND corrupted , who knows

 

[Vigintiduo]

The resistor is helpful if the cpu-mosfet cable between chip and mosfet ever gets disconnected while the switch is powered, which will result in the gate point "floating" which might result in the mosfet activating and burning out. As long as you remember to disconnect the battery before installation and don't power up again before the job is done and all points are measured, there's no point in adding a pull-down resistor.

In case you have semi-broken or short to hot line gate wiring inside your device. Or your rp2040 NAND corrupted , who knows

Oook now I get it. So as long as the rp2040 is working you're fine, but in the unlikely case of the wire or the rp2040 getting damaged, the mosfet would burn.
Thank you both for the explanation. I might start adding at least a 10k to my installs then, you never know.

Just one last thing that's troubling me: any idea of why the pull-downs on hwfly flex cables are significantly smaller that the ones suggested? I personally measured 500ohms.
Is it because they're garbage or 500ohms is still better than nothing?

 

[jkyoho]

Oook now I get it. So as long as the rp2040 is working you're fine, but in the unlikely case of the wire or the rp2040 getting damaged, the mosfet would burn.
Thank you both for the explanation. I might start adding at least a 10k to my installs then, you never know.

Just one last thing that's troubling me: any idea of why the pull-downs on hwfly flex cables are significantly smaller that the ones suggested? I personally measured 500ohms.
Is it because they're garbage or 500ohms is still better than nothing?

those are 2x1000 ohm(minimum?) in parallel so 500 ohm when you measure in circuit.
pull down resistance value is mosfet/circuit based, I tried 1k ohm with 8342 mosfet and was having glitch issue then increased to 33k ohm. So this value is YMMV

 

[Dee87]

Thats like a airbag on your car. You dont need if you never got into accident

Thats like a airbag on your car. You dont need if you never got into accident

I disable them as soon as I get new a car, do u know how expensive they are Xd

 

[falaschi]

GN guys, i need a little help. I'm doing hwfly to the switch of My kids. But i have bridged a mini capacitor, Will be the desoldering wick enough to fix My error? I was installing the Flex but i remove it entirely trying to leave the área clean to try to fix this. Thanks in advance and sorry for My English.

Any help?

 

[Vigintiduo]

GN guys, i need a little help. I'm doing hwfly to the switch of My kids. But i have bridged a mini capacitor, Will be the desoldering wick enough to fix My error? I was installing the Flex but i remove it entirely trying to leave the área clean to try to fix this. Thanks in advance and sorry for My English.

If you use a desoldering wick you might end up knocking off the capacitor.
From what I can see, maybe it would be better to apply a generous amount of flux, hold the capacitor down with something like tweezers and applying heat with a soldering Iron, removing the excess solder.
You might also use hot air, bit I'm not a fan of that because you might end up reflowing the SoC and usually it's not a good thing because it might end up needing a reball in a few months

 

[falaschi]

If you use a desoldering wick you might end up knocking off the capacitor.
From what I can see, maybe it would be better to apply a generous amount of flux, hold the capacitor down with something like tweezers and applying heat with a soldering Iron, removing the excess solder.
You might also use hot air, bit I'm not a fan of that because you might end up reflowing the SoC and usually it's not a good thing because it might end up needing a reball in a few months

TY. This caps are so tiny, i'm going to try that with flux paste and a slim soldering pen. Wish me luck!