Hacking Hardware Picofly - a HWFLY switch modchip

[frozenboy]

Here's two easier/safer mosfet positions on the back of the motherboard for the Switch Lite. They're both working fine. I moved the rp2040-zero LED to the home button led while i was at it just to test. Looks pretty neat, but not very useful.
I will personally not be using these points since the added time it takes to remove the motherboard makes it not really worth it for me, but I guess they might be helpful for people with less experience who are afraid of the apu caps.

I believe the big pad super easy position on the back for the OLED that I posted about before should be the standard recommendation though; it is far superior to all other locations (the pads are even pre-tinned!) and the motherboard has to be removed anyway.

Thanks, more choice, but I prefer soldering in to the cap, it easy to melt than this big via, because the heat is hard to concentrate to the large surface of the via and a cold point is easy to happen.

 

[Takezo-San]

Does anyone know where the resistor is on the RP2040 chip for the hwfly model... I want to add a resistor. because I can't enter ofw

 

[abal1000x]

Does anyone know where the resistor is on the RP2040 chip for the hwfly model... I want to add a resistor. because I can't enter ofw

Just check with multimeter the capacitor that connected to the CMD/CLK/Dat0, its 47ohms.

 

[roxzii]

Hi everyone!

I did an install, and at the end the diode values seemed to check out (the CPU pin was a little above 0.900 but my multimeter shows direct probe to probe as anywhere between 20 to 120, so I figured it would be inside the 0.900 range). So picofly works, no sd card screen, all good. After I put in sd card package black screen. Removed sd card, pressed volume+/- to go to OFW, purple screen. Purple screen means I screwed up CMD point. Fixed it.

Now I get a blue screen, so it seems I may have screwed up more than one thing. Everything I found pointed to the APU, so I removed the hwfly flex ribbon, disconnected the pi, still blue screen. I was really careful when installing the flex cable, I knew those caps are heat sensitive so I tried to be as quick as possible, pre-tinned the cable, plenty of flux and everything.

Is it possible I fried one of the two caps and that's the reason for the blue screen? Since the pico manages to glitch shouldn't the caps be fine? I suppose that if there was a problem with those SP1 and SP2 caps the pico would give an error code.

If photos are needed of RST I can post, but since I get to the no sd card screen I'm guessing that shouldn't be the problem. Also don't have photos of the apu with the flex cable since I removed it for testing.

Sorry for the long read, just wanted to explain the problem the best way possible.

Appreciate any help!

So a few updates:

Mangled both SP1 and SP2 caps, have not been able to replace them. Saw in a post soldering the hwfly flex directly to the pads would work.

At this point I was getting anxious and took some anxiety meds (pro tip: don't)

From there the screw ups kept growing. First I (very stupidly, I know) soldered the hwfly flex tape directly to the pads WITHOUT disconnecting the battery. Just from that I'm assuming I killed the switch. But there's more.

Since I was working with the APU shield off I managed to touch the picofly's contacts to the DRAM metal housing where the shield fits over. I heard some kind of sound and immediatly realized.

Since then picofly gives RST error (which it never did before). Tried another picofly, no leds at all. Still have't installed the old one back.

I'm assuming it's something burnt from soldering with the battery on that's causing that RST problem, because at least the pico was working flawlessy before.

Anyone know if this is salvageble or completely dead?

I can post pictures of current install but figured that wouldn't help much.

Thanks in advance!

 

[deeps]

Sorry, I mis-credited this discovery. Amazing. I have a lite coming in tomorrow I thought I’d try this after how much I enjoyed how neat it was on OLEDs, but you’re right. Lites are pretty anonying to dissemble.

I believe @abal1000x deserves about 75% of the credit here though since he came up with the idea of putting the mosfet on the apu power supply on the back. I merely followed the traces

 

[chronoss]

After the 94/94/94, first try error *== then power off, and power on, normal, is it correct?

Config normal and last atmo with fusee it work always on second try with error package2 on first try...

 

[cowboy619]

So a few updates:

Mangled both SP1 and SP2 caps, have not been able to replace them. Saw in a post soldering the hwfly flex directly to the pads would work.

At this point I was getting anxious and took some anxiety meds (pro tip: don't)

From there the screw ups kept growing. First I (very stupidly, I know) soldered the hwfly flex tape directly to the pads WITHOUT disconnecting the battery. Just from that I'm assuming I killed the switch. But there's more.

Since I was working with the APU shield off I managed to touch the picofly's contacts to the DRAM metal housing where the shield fits over. I heard some kind of sound and immediatly realized.

Since then picofly gives RST error (which it never did before). Tried another picofly, no leds at all. Still have't installed the old one back.

I'm assuming it's something burnt from soldering with the battery on that's causing that RST problem, because at least the pico was working flawlessy before.

Anyone know if this is salvageble or completely dead?

I can post pictures of current install but figured that wouldn't help much.

Thanks in advance!

Need an ammeter to check power draw. I would toss the pico and try and get the device to boot normally then work back wards.
Does it still boot?

 

[Arakon]

Shouldn't there also be some CPU power supply pins on the top side? Or are they really only on the back of the board? I personally hate taking out the entire board more than soldering to the APU...

 

[roxzii]

Need an ammeter to check power draw. I would toss the pico and try and get the device to boot normally then work back wards.
Does it still boot?

With the original pico (that may have shorted on the shield) I still got leds, but indicated RST point error (2 short yellow lights). Never had an error there before and redid the solder. Value around 0.800 (less since my multimeter is bad, really need to get one not so bad one). So the pico somewhat works, I just don't know if this strange RST point error is a pico problem or I just fried the switch when I soldered SP1 and SP2 to the pads without disconnecting the battery.

With the pi's 3.3v and ground disconnected I'm pretty sure I just get a black screen, no more blue screen, but I was pretty frustrated at the time so I'll get back to you on how OFW without pico works. But I think that was the thing that first made me think I had fried the switch by soldering with the battery attached.

 

[cowboy619]

With the original pico (that may have shorted on the shield) I still got leds, but indicated RST point error (2 short yellow lights). Never had an error there before and redid the solder. Value around 0.800 (less since my multimeter is bad, really need to get one not so bad one). So the pico somewhat works, I just don't know if this strange RST point error is a pico problem or I just fried the switch when I soldered SP1 and SP2 to the pads without disconnecting the battery.

Does it boot to ofw?

 

[deeps]

Shouldn't there also be some CPU power supply pins on the top side? Or are they really only on the back of the board? I personally hate taking out the entire board more than soldering to the APU...

The chip responsible for creating the power rail is on the back and the trace simply goes straight through the board to the apu pins. so no, unfortunately not

 

[roxzii]

Does it boot to ofw?

I mean since I installed the picofly it never did, I got that blue screen many people are getting with OLED's. But now I think it's just black, but I can only confirm in a few hours

 

[cowboy619]

I mean since I installed the picofly it never did, I got that blue screen many people are getting with OLED's. But now I think it's just black, but I can only confirm in a few hours

Probably dead and shorted the system with the battery. Need to check m92 and Bq for shorts and perhaps get an ammeter to check power draw

 

[roxzii]

Probably dead and shorted the system with the battery. Need to check m92 and Bq for shorts and perhaps get an ammeter to check power draw

Thank you, will check those.

By ammeter you mean one of these? (Sorry, I don't remember if I can post links to shopping sites so I attached a screencap)

 

[DejavuStudio]

Confirm that a single mosfet from backside mainboard just instantly glitch the sw oled, how sweet!!!

 

[Dee87]

I mean since I installed the picofly it never did, I got that blue screen many people are getting with OLED's. But now I think it's just black, but I can only confirm in a few hours

I installed over 60+ switches now from that 30+ Oleds and i never had an issue , all these blue screens are 100% related to istallers issue and nothing else i dont care what anybody else says

 

[deeps]

Yes its too pricey, i learn kicad rn, and gonna reverse pcb the adapter.

You can get 10 for 50 usd if you msg them, but it's still rather pricey and probably cheaper to design and order pcb yourself. it's a very simple board, 2-layer 0.6mm thick with only the important points connected between the sides.

 

[roxzii]

I installed over 60+ switches now from that 30+ Oleds and i never had an issue , all these blue screens are 100% related to istallers issue and nothing elde i dont care what anybody else says

Don't get me wrong, never said it was anything other than that, 100% agree with you. I just wanted a diagnose of what I did wrong because on paper everything went right. Just wanted to find what my error was (way back all the others I made trying to diagnose).
But now everything indicates that I killed it out of pure stupidity so I guess I'll never find out.

 

[Dee87]

Never said it was anything other than that. I just wanted a diagnose of what I did wrong because on paper everything went right. Just wanted to find what my error was (way back all the others I made trying to diagnose).
But now that everything indicates that I killed it out of pure stupidity so I guess I'll never find out.

for that u need to go Deeper.
what dat0 adapter did u use ?

 

[roxzii]

for that u need to go Deeper.
what dat0 adapter did u use ?

As far as I've read since, the bad one. This pack. But I did that sthetix trick of cutting that little lobe to the side.

Also final result. A little crooked for 2 reasons, it wanted to go in deeper like that and I read it was better for it to be a little crooked not to make contact to dat1.

EDIT: Edited first image of adapter, was the wrong one, now is right.