Hacking Hardware Picofly - a HWFLY switch modchip

[abal1000x]

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[MegaDeKay]

I have new theory on why the cmd resistor died. Try to change the cmd resistor in pico which is 47ohms into around 100ohms.

The cmd resistor (on the board) is a pullup resistor 4k7 to 1.8v. I am not sure, whether picofly send something to cmd line, which i assume it is. And i am not sure on what voltage the rp2040 send the signal, which i assume its 3.3v. So It could be that the current flows in the cmd line is too big for that cmd resistor (4k7) to handle, so pico burns it. The easy one is to increase the resistor on the pico to 100 ohms. Its still on the range of emmc specification, and also limiting the current. Might solve the mysterious cmd burns issue.

So your theory is the 4k7 pullup is burning out because of whatever the pico puts out? This can't be it if so. The most the rp2040 can put out is 3.3V and the minimum 0V. Let's say that somehow a full 3.3V shows up across that 4k7 resistor. Basic Ohms Law says no more than 0.7 mA (3.3V / 4700 Ohms) can flow through it. Whatever is cooking those resistors, it isn't current.

This is why coffee is bad.

HERESY!

I don't check in for like a week and the thread catches on fire

I believe I saw rehius mention somewhere some of the issues are caused by the 2.74 firmware with 300mhz speed?

curious

Yes, in the AIO thread he stated a theory that not all pico boards can handle the 300 MHz speed. This might be why older versions like 2.67 and 2.73 work better for some people. So he now has 2.73 as the latest on his firmware post in this thread.

 

[abal1000x]

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[some1ne]

I've done 5 picofly installs by now, but my personal oled switch is having some issues. It's turning off by itself after going to sleep (emummc). What could be causing this? Is this caused by the RST point?

Edit: Actually, it also does this outside of sleep mode. It's almost as if the power button is being held down. Sometimes it does this, but sometimes not. When it does, the switch freezes, the screen fades to black and then the switch turns off. Same thing happens in OFW. Doesn't seem to happen in hekate.

 

[cgtchy0412]

His normal point ripped
I guess he doesn't have any choice.

Are you sure that resistor is the main cause of purple screen?

Acctualy is not the resistor itself, rather its connection with the board, its easily disrupted even only by soldering a wire to it can result in purple sod. So i consider it dangerous and not worthy.
But if there is no choice then just be carefull and dont panic if it suddenly psod.

 

[MegaDeKay]

What is the maximum current (rated) that tiny resistor could flow?

Looks like around 50 mW. In this circuit, P=I^2 * R = (0.0007) ^ 2 * 4700 = 2 mW. No problem. They wouldn't have used such a tiny resistor if they were at all worried about power rating in a circuit in the range of 1.8V - 3.3V. The resistor value guarantees a safe design.

 

[abal1000x]

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[cgtchy0412]

Is it possible that these resistor broken cause by a bad solder device. I've meet with some cheap solder device which have a huge leak electricity. Sometimes its electrocute me little bit if i don't use shoe.

Is there any recomendation from anyone here on what brand/model of solder tools that doesnt have this elec leak. Both solder tools only also solder station.. best if its under $50.
As i have now this cheap ($5) one with a little leak, only if im aware that i can feel it.
Luckily no issue yet until now.

 

[johndoenut]

Is there any recomendation from anyone here on what brand/model of solder tools that doesnt have this elec leak. Both solder tools only also solder station.. best if its under $50.
As i have now this cheap ($5) one with a little leak, only if im aware that i can feel it.
Luckily no issue yet until now.

View attachment 378919

Lol, I have this cheap iron too

 

[MegaDeKay]

For the tiniest resistor 1/20W it could flow 15mA so its totally safe.

If theres leak electricity on some bad solder device, could it possible to destroy those resistor when soldering it?

I'm not an expert in this particular area, but resistors are generally very robust. That 1/20W rating is the rating it can take all day long and at rated temps (like 70C). I'm sure it could briefly dissipate much higher power surges for a short period of time. It would seem to me that other components in the circuit like the APU and the flash would be much more sensitive to a crappy non-ESD safe soldering iron. The transistors in the APU are fabbed from a 40 nm process - much smaller and more sensitive!

 

[cgtchy0412]

I've done 5 picofly installs by now, but my personal oled switch is having some issues. It's turning off by itself after going to sleep (emummc). What could be causing this? Is this caused by the RST point?

Edit: Actually, it also does this outside of sleep mode. It's almost as if the power button is being held down. Sometimes it does this, but sometimes not. When it does, the switch freezes, the screen fades to black and then the switch turns off. Same thing happens in OFW. Doesn't seem to happen in hekate.

Yup, that a sign of cpu reset, can be from any cause.
Please can check the soldering on pico specially rst point whether its short with the metal shield (any sharp/protude solder point, bad kapton isulation or when you are using only double tape without kapton).. double or triple the kapton layer also..
Also try assemble it without the metal shield just to test the theory.

 

[abal1000x]

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[cgtchy0412]

Lol, I have this cheap iron too

Dont let it trick you, i swept 25 switch with this little boy without casualties.
But i need to level up and find a better tools.

 

[abal1000x]

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[some1ne]

Yup, that a sign of cpu reset, can be from any cause.
Please can check the soldering on pico specially rst point whether its short with the metal shield (any sharp/protude solder point, bad kapton isulation or when you are using only double tape without kapton).. double or triple the kapton layer also..
Also try assemble it without the metal shield just to test the theory.

I just tried using the switch without an SD card. It's working without any crashes so far, however the digitizer (touch screen) stopped working. Maybe the digitizer is being shorted somehow?

Edit: now the touch screen doesn't work on OFW anymore, but does on Hekate and Atmosphere

 

[cgtchy0412]

I just tried using the switch without an SD card. It's working without any crashes so far, however the digitizer (touch screen) stopped working. Maybe the digitizer is being shorted somehow?

Where did you take the 3.3v also Ground point from?

 

[abal1000x]

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[some1ne]

Where did you take the 3.3v also Ground point from?

3.3v from the capacitors, same ones used by the hwfly and instinct flex cables.
Ground from the round pad to the right of the board, same one shown on the picofly guide pdf from here.

 

[abal1000x]

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[cgtchy0412]

https://vi.aliexpress.com/item/1005003373147424.html?spm=a2g0o.productlist.main.13.31daf78fyfNib3&algo_pvid=28127e41-9010-443b-ba8a-b17afe33a81b&algo_exp_id=28127e41-9010-443b-ba8a-b17afe33a81b-6&pdp_npi=3@dis!IDR!264634.0!140299.0!!!!!@212244c416872306527158070d073c!12000025477845350!sea!ID!3430123615&curPageLogUid=DoBOLZJb7Kxk

This is the cheap version of pinecil which lately hacked.
https://github.com/atc1441/ATC_stc_solder_iron

Its pretty interesting too.

Thanks, considering ill buy this now.