USB OTG template. Is it possible to use it with just one port?

hishnik

hishnik

Hello.
I've read this article and found it usable. I want to make one port of my home router to be a serial one, but didn't found how to make it with just one usb port? Some ports are seized by HDD's already.
Can somebody tell me the truth?
Thank You.
 
hishnik said:
I want to make one port of my home router to be a serial one,
Click to expand...
I don't think you can just make any port a serial one.
The device has to support OTG. It will only be one port among many USB ports.
Many times a Mini or Micro USB connector to denote its difference.
What device exactly are you trying?
 
Serial Console over USB is going to need support from the device. Its is called OTG or On the Go.
Primarily an Arm board constraint used due to its small port size. But it offers a serial console over usb to usb.

So what do you need the serial connection for? If console then OTG is probably needed.

You could still plumb a USB to USB connection without a console if you just need interconnection.
The problem with that is the Router side USB port. It is probably only configured for Mass Storage device.
So might need to be running OpenWRT on the Home Router for this method to work and it would probably require some configuring.

Just guessing. What is the 'home router' device?
 
DISCLAIMER:
USB to USB connections involve power. You must be aware you can fry your gear if you get this wrong.
Don't directly plug USB to USB computers (or Home Routers).
That is what makes OTG special. It is isolated power.
 
Usually modern electronics are somewhat protected and you might not fry them but here is a real USB example.

Dell Edge 610 has miniUSB jack for serial console.
It must be an un-isolated circuit as when I plug the USB cable into my serial console machine it causes it to reboot.
So the outside power source causes it to fault and reboot. Perhaps there is a special Dell cable with data only lines.
That is best case scenario.
Worst is white smoke.
 
It's a usual 1L x86_64 PC, like this one. Those two serial-ports are used for UPS and Ethernet-switch management. I want to have out of band console. USB OTG is a nice choice, but I don't understand from your reply: is it possible to allocate just one port for that or it's totally not possible? Sorry for this misunderstand, I'm not a native English speaker.
 
I do not have any experience beyond OTG hardware for USB connections.
My feeling is if you isolate the power then you could use ttys to make a USB port a console.
Never tried it.
 
fwabi9 said:
2 Prolific PL2303 cables<USB to serial adapters> and a null modem <cable> in between.
Click to expand...
forums.freebsd.org

headless console USB-to-USB

Hi all, I use an HP Pavilion laptop without screen (torn off) as a headless home server. I access it either on the console, plugging in an external VGA monitor, or via ssh. Lately I got locked out because: 1. i915kms was deprecated and blacklisted in /boot/loader.conf, 2. I messed up with...
forums.freebsd.org forums.freebsd.org
Kinda hacky but should work.
 
Better yet ditch that and use inline crimps on these:

www.ebay.com

NEW FTDI Chip TTL-232R-3V3-WE USB To TTL Serial Cable Wire End Version 1.8m | eBay

Find many great new & used options and get the best deals for NEW FTDI Chip TTL-232R-3V3-WE USB To TTL Serial Cable Wire End Version 1.8m at the best online prices at eBay! Free shipping for many products!
www.ebay.com
I prefer genuine FTDI. They work very well.

I just bought some 'wire end' models for my gpio connectors project. Very versatile.
Plus you can make the length to suit. Heat shrink for professional look.
 
I wonder about cutting up some old usb cables and using just tx/rx lines alone. Maybe Ground too.

In my post above that adapter has TTL converter and only 3.3v. Not needed for your usecase.
None of that would matter if you used two identical adapters. Just some unneeded translation.
 
any usb to serial will work as a serial tty but if you need it to work in loader(8) you can try something like this
https://forums.freebsd.org/threads/...board-with-no-serial-ports.87852/#post-596797
(add efi support for your device) but instead the driver mentioned in the link above you need something like
github.com

edk2-platforms/Drivers/OptionRomPkg/Bus/Usb/FtdiUsbSerialDxe at master · tianocore/edk2-platforms

EDK II sample platform branches and tags. Contribute to tianocore/edk2-platforms development by creating an account on GitHub.
github.com github.com
 
Thank You, but I'm looking for preferably software solution. You know all those SDNs, SDRs, SDSs, SDIs...etc, maybe soon we will see SD...tethering?
 
I broke power lines of USB-cable and followed this manual, and...nothing happened.
Does somebody have success story in achieving USB-device functionality on FreeBSD?
 
Just as a primer here is how OTG works.

First hardware. OTG is a chip that resides on your board. It is wired to one of the USB ports.
What it does it provides a protocol and transport mechanism for your USB port to provide a console.

That is what is missing when you simply wire two computers together via USB data lines.
(As I crossed out in a post above after thinking about it)
You have no protocol or handshake methods for the two computers to communicate. That is what OTG does.

OTG also needs support in the BIOS.
Early Up-Boards needed a BIOS update to make this feature work, even though an OTG chip was present.
 
You must log in or register to reply here.
Back
Top