Question USB issue using homemade cables

[lesthegringo]

Hi all

First of all, I need to make it clear that I am not a PC savvy guy, my thing is that I am building a DIY home cockpit so that I can use a flight sim game. This uses various things including Arduinos, OLEDS, screens switches, all of which I have received assistance from other like minded people.

However this particular issue is one we are unable to understand so would like to seek assistance here. Essentially it is that the USB connection for one part appears to be acting in an unexpected way

My rig uses four Nobsound USB amplifiers to drive eight Dayton Audio bass transducers. I have a four port USB hub that connects to the for amplifiers, with a 24v power supply powering the amps, so they are not drawing power via USB, however I still elected to use a powered USB hub. All these components are mounted onto a dedicated module that fits into the back of the sim rig chair, requiring only one USB input plus mains power supply.

Where the complication for me has set in is where I have had to, for construction purposes, make the USB line in sections. This is due to the line having to pass through a console, then to the seat, and finally to the amp module. To make it in one piece would be messy and also leave the cable exposed to damage

First is a male to male USB A 3.0 cable from the PC (motherboard USB 3.0 socket), to a captive female to female USB 3.0 connector mounted on the front of the console.

A USB 2.0 cable with a USB A connector at the front then runs inside the console to the rear, where the wires have been soldered into a four way male G12 aviation connector mounted on a dedicated output plate (shared with the G16 connector for the mains power).

A short fly lead with G12 female connectors at either end then connects to the seat where an input plate again with a G12 and G16 connector for the USB and mains input are mounted. These then have internal fly leads to the power supply coupling and one last G12 connection for the USB, which is then soldered to the input lead for the hub. It sounds more complicated that it is, and when you actually see it it makes a lot more sense that my word salad above. It is also very neat, with minimal exposed wires

So the issue I have is that I connect it all up , and Windows duly recognises the four amps and it all starts working fine. Then about an hour later, the USB amps are no longer recognised, and disconnecting and reconnecting the USB connection does nothing, apart from sometimes, but not always, coming up with a 'the last USB device connected was not recognised'.

To test, I have rigged up a single USB cable that goes directly from the Motherboard to the USB hub input, bypassing all my home made wiring and this does not fail over time, meaning something about my setup is causing the issues. I have checked continuity, resistance, short circuits on all the cables I have made and cannot find anything wrong, meaning that something else must be at play. The fact that it works fine for a while in itself shows that the cables appear to be fundamentally ok in theory.

Can it be that too many connections can cause interference, or maybe pick up some interference from outside?

If anyone is able to give any pointers I would be pleased to try them

Les

 

[kerberos_20]

try disabling usb selective suspending in power profile settings
press start, type "edit power plan", change advanced power settings, usb suspend settings -> disabled

https://imgur.com/ruQQu5k

View: https://imgur.com/ruQQu5k

 

[BFG-9000]

As you'd expect, most XLR-type connectors are not rated for high frequency use as they are mostly intended for analog audio (microphone) or power transmission. There are some data-rated types that can meet the transmission performance requirements of Cat5e--but that only operates at 100MHz. USB 2.0 runs DDR so at 480Mbps that's 240MHz squarewave. USB 3.0 is more complicated as it's spread-spectrum but runs somewhere around 2.5GHz, which is why poorly shielded cables can interfere with wifi so badly.

Connectors and terminations not designed for high frequency use will have internal reflections which can interfere with the signal and severely reduce the usual USB reliable length limit of 5 or 3 meters. The solution is to use the proper rated connectors for your application. If you want ruggedness and the security of a locking plug then there are these:

 

[lesthegringo]

try disabling usb selective suspending in power profile settings
press start, type "edit power plan", change advanced power settings, usb suspend settings -> disabled

https://imgur.com/ruQQu5k

View: https://imgur.com/ruQQu5k

Thanks, I'll give that a go - but would that also explain the 'USB device not recognised' message?

As you'd expect, most XLR-type connectors are not rated for high frequency use as they are mostly intended for analog audio (microphone) or power transmission. There are some data-rated types that can meet the transmission performance requirements of Cat5e--but that only operates at 100MHz. USB 2.0 runs DDR so at 480Mbps that's 240MHz squarewave. USB 3.0 is more complicated as it's spread-spectrum but runs somewhere around 2.5GHz, which is why poorly shielded cables can interfere with wifi so badly.

Connectors and terminations not designed for high frequency use will have internal reflections which can interfere with the signal and severely reduce the usual USB reliable length limit of 5 or 3 meters. The solution is to use the proper rated connectors for your application. If you want ruggedness and the security of a locking plug then there are these:

Understand, the connectors I am using were clearly designed for less specific use, however they do fit in very well with the look of a flight sim cockpit

The total cable run is actually about 1.6 meters, so well below those length quoted, however I suspect that is using fewer, correct type connectors. The ones you show there are simply not available here (Qatar) and I have to use what is available locally, which is pretty limited unfortunately. However one point I noted is your differentiation of USB 2.0 vs 3.0 - the only reason I used any USB 3.0 hardware is because it was what I had, but the equipment used doesn't need it, 2.0 being enough. Is is possible that changing all the 3.0 parts and cables to 2.0 ones and using a 2.0 port on the motherboard that it would reduce the possibility of issues?

Les

 

[BFG-9000]

If you plug it into a USB 2.0 port then the five USB 3.0-only wires aren't connected to anything anyway, so no need to remove them. Only the four USB 2.0 wires will be used, because the USB 2.0 port only has four contact pads in it.

It is already running in USB 2.0 because you have a USB 2.0 cable in there

 

[lesthegringo]

So does that explain why it works for a while, then stops working? I'm curious as to the reason for that, I still have other bits and pieces to do so need to try and avoid the same trap

The other point is, are the USB 2.0 ports on the motherboard different from the USB 3.0 one other than the extra wires? Does a USB 3.0 port 'downgrade' the frequency etc to match a 2.0 setup connected to it?

 

[BFG-9000]

There's only so much data corruption the drivers will accept before they decide something must be wrong with the device. "The last USB device connected was not recognized" means the host can see the voltage pulse from the VCC momentarily connecting through a 1.5kOhm resistor so knows something is there, but cannot enumerate the device (configure its speed and assign it an address).

USB 3.0 is fully backwards compatible and will first negotiate to the highest speed both ends support, then fallback to slower speeds if needed, even to USB 1.0 full (12Mbit) or low (1.5Mbit) speeds. It's still a USB 3.0 controller however, so uses its xHCI driver even at the lower speeds. A USB 2.0 controller uses EHCI drivers for SuperSpeed (480Mbps) and either OHCI (NEC) or UHCI (Intel, VIA) drivers for lower speeds. This is relevant because some hardware (including the hub) or drivers may be more tolerant or compatible with running out-of-spec or with some peripherals than others. But I assume by now you've already tried your USB A 3.0 cable in a USB 2.0 motherboard port.

The only two wires that matter are the middle two data lines on the USB A 2.0 connector--the other two are only power and ground which are probably insensitive to crosstalk or noise. Make sure there's no excess solder or wire anywhere along those two lines as that would cause echoes. Try slightly lengthening or shortening them, or moving them to different pins on the connectors. And avoid running those two lines too closely together or alongside any other wires unless they are shielded with foil tape (normally they are run as a twisted pair to reject external interference induced into both lines, even in flat USB cables). High frequency signals often do not behave predictably so it's going to take some trial-and-error to reinvent the wheel--look at how Cat6 cables (rated for 250MHz operation) need to be terminated and have a very strict minimum bend radius, plus the wires cannot be untwisted more than 13mm.

 

[lesthegringo]

Thanks for the feedback. I did use old USB cables to make mine, on the basis that they were all colour coded and clearly were USB capable, plus some of them had plugs on one end saving me time. These all had either foil or wire braid sheathing and by sheer luck I chose to keep the cables as neat as possible so the ends soldered to the connectors were kept very short.

Yes, I did try the motherboard USB 2.0 connection, to no avail. I even tried connecting via the PCIe USB 3.0 expansion card in the PC, again with no success. Initially it worked, then after a half hour or so it stopped

I suspect I will have to accept a more compromised setup and put up with a less aesthetically pleasing solution. That also will compromise the modularity a little (we move a lot) but I see the drawing board beckoning!

Thanks to all that gave me input and help on this!

Les

 

[Paperdoc]

I can see two items that could cause your issue.

1. The G12 connectors. Clean signal propagation at high data rates is affected by the impedance of the entire communication line. Impedance is a frequency-dependant parameter, and can be considered as an "ideal" line that includes resistance, capacitance and inductance components all along that line. Any connector includes particularly some capacitance and inductance elements added to whatever the cable itself contributes, so using the RIGHT connector can be important in high-frequency (data rate) communication lines. In the case of USB cables and lines, the control system requires that signals sent out generate responses within a maximum time frame, and the actual response time can be delayed by a cable with excess capacitance and / or inductance. Failure to meet this response time limit will be considered a communication error. Most comm management algorithms allow for re-tries if an error happens and that often succeeds so the "problem" is ignored. SOME such systems keep track of how often such errors occur and will treat frequent errors, even those solved by re-tries, as permanent errors and shut down. This this type of problem MAY appear to be intermittent. It is possible that your system has enough of these impedance mis-match issues due to the connectors to cause your problem. Different connectors designed for USB2 or USB3 cables MIGHT avoid that. OR, NOT having those connectors at panels - using a continuous cable passing though a panel hole - might help.

2. Cable Shields. The USB specs for both USB2 and USB3 include the requirement of an overall shield in the cable that surrounds the wires in it. This is in addition to the shields around individual twisted pairs in the USB3 system. The overall shield is supposed to connect the metal outer shells of the connectors at each end of the cable, and is a separate connection from the Ground lines in the cable. The shield prevents pick-up of noise signals in the cable data lines from external sources in the vicinity of the cable because those noise signals can alter the information in the data and result in communication errors. Some low-cost cables simply do not have this outer shield, or may have a shield that is NOT connected properly to the exterior shells at both ends. Further, even if the shield is present, the USB specs require that the end-to-end resistance of that not exceed 0.6 Ohms. Now, that can be very hard to measure for any home DIY person, so checking that on YOUR cables may be difficult. Sometimes the only solution IF that appears to be the issue is to go buy an expensive "premium" cable in the reasonable hope that it WILL have a proper shield in it.