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| Malenko:
I can understand the desire for a single USB cable, but wouldst it be a safer bet just to zip tie 2 together? run them from seperate USB ports (maybe one from the front, one from the back, I'm not 100% how the power works on your board) then go with 2 unpowered hubs to split the load? |
| MonMotha:
--- Quote from: richms on January 21, 2009, 08:16:43 am ---The computer I found in the inorganic collection with a nice burnt trail from the melted front USB port, along the flyleads, to a charred header on the motherboard and some darkened areas all the way to the ATX connector shows that some do absolutely nothing for protection. The thing I find laughable is the HDDs that come with a Y cable to get more power, when there is nothing to request the power from the second port, so they are violating spec anyway, and since they are feeding the power straight to a 2.5" HDD they cant use diodes to prevent issues with connecting 2 5v supplies together. A friend had mystery problems with their PC with that plugged in, turns out some USBs were jumpered for 5vsb, some not, and joining them made for an unhappy computer. Its crazy that the USB association dont go after the pervayors of non compliant junk for saying that they are USB for the stuff like warmers and chargers etc which are probably responsible for a hell of a lot of blown USB ports on office PCs that "just broke one day" --- End quote --- Hosts and hubs that do not implement any meaningful form of overcurrent protection violate the specification and should not display the USB logo. If they do, report them to the USB IF. If it's a big enough vendor, they might manage to pressure them to fix things. In theory that HDD can get 100mA off the "extra" port without enumerating on it, but you are right that there's no easy way to combine them together safely. There are some solutions involving various SMPS converters, but I have yet to see anything employ them. I'm not sure that pulling this 100mA unit load without any intent to enumerate is allowed (and you certainly won't comply with suspend current requirements), but I don't see anything in the spec to prohibit it. As for the USB IF, they do occasionally go after people who use the USB logo on non-compliant products. In theory, to use the logo, you have to actually have passed the USB IF's compliance testsuite and this has to be verified by one of their "blessed" agencies, though in practice they don't seem to care a whole lot as long as your device actually is pretty compliant. The logo is trademarked, though, and they make it very clear that you cannot use it on non-compliant devices just because it has a USB connector. Unfortunately, the USB spec is a giant quagmire of ugliness, so I can understand some minor deviations from the spec here and there. Still, many of the things devices and hosts do that they shouldn't are clearly documented as being against the spec, yet devices and host do it anyway. There was a working group to address many of these power concerns on USB. Info appears to be at http://www.usbpluspower.org/ and appears unaffiliated with the USB IF. The intent was to allow a USB port to power medium-power devices such as printers, scanners, hard drives, and larger battery chargers in mobile devices. It involved adding on to the USB plug and making it larger (to add more power lines) in a backward compatible manner (standard USB 'A' plugs would still work). Dell adopted one of their reccommendations on some of their laptop docking stations at one point. I'm not really aware of anyone else adopting this stuff though it looks like it may be popular in PC based POS systems. |
| blind_dado:
This is the powered hub I use in my cab, which is expensive, but will never fail you (there is a seven port version too). It's metal, and I love its heavy duty feel. Available at USB Gear: http://www.usbgear.com/computer_cable_details.cfm?sku=USBG-4SU2MLA&cats=104&catid=187%2C188%2C104%2C653%2C210%2C212 |
| Chris:
Wow, that thing is a tank. |
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