[HARDWARE] UART Cable time

[Jovan Riparazioni]

I've got an Octoplus Box. I've tried connecting S8 G950F and Note 8 N950N (both Exynos) to UART with normal micro USB adapter with a 525k resistor and a micro to USB C adapter at baud rate 115200. Octoplus Box has a FTDI USB2Serial adapter. I manage to get a really short output, but I cannot reach the console. I opened sboot.mbn of Note 8 with HeX editor and I've found that part of the code has a list of UART commands that I used to get in sboot console of S7 and S7 Edge (both global F models). I just can't figure out how to get some input. I managed to get output even from Galaxy Tab S2 (T819), but gives me no input option. I borrowed from a colleague an EFT box UART C cable which has a PL2303 serial2USB adapter, but I don't get even output when I try to connect N950N with a combination of keys. The phone behaves different when the keys are pressed. I think the problem is that this cable has a voltage and unlike box cables can be used to charge the phone. If anyone has any suggestions, that would be great.

 

[frostydawn]

Still anyone hasn't figured out the way?

 

[Zfence]

So nothing yet

 

[TheMadScientist]

So nothing yet

No

 

[Zfence]

No

Oh well I guess I'll do my own testing now.

 

[0sm1um]

a VERY tricky DANGEROUS and limited way to get uart over usb

I may suggest a VERY tricky and limited way to get uart over usb.

• Hack MUIC kernel driver to multiplex uart on usb by shell command.
• Port a bootloader (for example u-boot) -
  • Prepare u-boot build.
  • Load u-boot build to phone.
  • multiplex uart on usb manually.
  • kexec to bootloader build.
  • Repeat if necessary.
• Add bootloader feature to switch uart on usb by key combination.
• Chainload your bootloader with stock bootloader with chosen keys pressed.
• Congrats, you got uart on usb at 2nd bootloader, and you'll be able to see early kernel logs, until kernel MUIC driver get loaded, and switch MUIC back to it's initial state.

Proofs of concept - u-boot code for Samsung A5 2017 - <replace with github url>dsankouski/u-boot/tree/a5y17lte/board/samsung/a5y17lte#getting-uart-output-via-usb-uart-cable

Note, I actually not tested this instruction, as I gone different way with A5 2017 u-boot port - soldered uart on motherboard