It's definitely no optional. The TI part is designed for that. Not sure about the others.
The HV bus is definitely optional - but most stationary devices - hosts, docks,etc can supply that no issue I would say that we will see big values on the HV bus from AC mains powered devices. On Tuesday, June 2, 2015, Bob Camp <[email protected]> wrote: > Hi > > The point that was made by the OP was that the new USB-C spec starts out > with a “3A default” rather than > 500 ma. Since this stuff is just hitting the market, only time will tell > how the vendors decide to handle that > “requirement” with multi port gizmos. > > With (now apparently obsolete) USB-3.0, hubs in the 8 and up range are > indeed out on the market. > I *assume* that the large port count stuff will also show up for USB-C. > > Bob > > > On Jun 2, 2015, at 4:44 PM, Jim Lux <[email protected] <javascript:;>> > wrote: > > > > On 6/2/15 4:07 AM, Bob Camp wrote: > >> Hi > >> > >> The one thing I would be a bit careful about is the power levels. > >> > >> Consider an 8 port hub: > >> > >> 5V 3A from each would be 24A total. That’s pretty unusual. Most hubs > >> give you one or two high current outputs. > > > > There are very few 8 port hubs and lots of 7 port hubs (at least for USB > 1 and 2). A 7 port hub is two 4 port hubs daisy chained. For commercial > products, most (if not all, I've not checked for sure) have only 2 of the > high power jacks. > > > > The power switching and control protocol is non-trivial, especially if > you are connecting and disconnecting devices. On windows (and other OSes, > too, I imagine) there's a whole thing where the OS tries to keep track of > the state of the whole tree of USB devices, so that it doesn't try to send > a "power up" message to a device that downstream of a "powered down" hub > until it's sent the "hub power up" message. > > > > There's also some weird (and entirely within spec, apparently) behavior > of a hub where it, say, has 1.2 Amp total capability, so the first two 0.5 > Amp devices that are plugged in get the full allocation, and the rest do > not get the "high power" acknowledgement. Plugging in a combination of > high and low power devices (or, equivalently, enabling and disabling them) > can lead to things sometimes working and sometimes not. (the Knapsack > problem, which this sort of is, is NP hard, after all) > > > > I've also found devices/hubs that seem to use some sort of ad-hoc power > allocation scheme (actually measuring the power drawn, as opposed to just > saying "high power (500mA)" and "low power(100mA)" devices when querying > the device and/or looking at the pullup/pulldown on D+/D- > > > > One reference says "All USB devices enumerate as low-power devices at > first. After enumeration, the host examines the bMaxPower field of the > configuration descriptor for the device. If bMaxPower indicates that the > device is high-power, and the power is available, the host allows the > device to transition to high-power" > > > > the whole "if power is available" might be done in real time. > > > > And this causes real issues if you have a USB powered device that has > multiple power modes (I have a bunch of radar modules that started out > being USB powered, and have a low power "idle" mode and a high power > "transmitter and receiver on" mode) > > > > > > There's some complexity also with "bus powered" vs "self powered" hubs. > A bus powered only gets 500mA from upstream, so cannot really support any > downstream devices at 500mA: therefore, 100mA for each of the 4 downstream > devices, and 100mA for the hub itself (if needed). > > > > > > In any case, USB power management (and hub and device state management) > is substantially more complex than one might think, and lame software > drivers in the host can make it more complex; particularly if, as in most > modern systems, there's lots of power management going on for hibernation > and sleep modes. > > > > > > There's a whole bunch of command line commands for Windows to manage > this explicitly (if you don't want to use "device manager"). If you're > doing a lot of USB stuff on windows, you NEED the devcon command, which > gives a lot more visibility into the enumeration and hierarchy. > > > > USB power management http://support.microsoft.com/kb/817900 > > > > devcon command: http://support.microsoft.com/kb/311272 > > > > googling "Windows USB power management" will turn up a lot of info, too. > > > > > > devcon can also be used to deal with USB COM ports that move around or > disappear and reappear. > > > > I have a system that has 5 Teensy 3.1 microcontrollers hooked to it via > USB (emulating a very fast serial port). The problem is that when the > microcontroller changes USB device types depending on whether it's in > "bootloader" mode or "running an Arduino program" mode. > > > > I think devcon might also be a good way to suppress the notorious "GPS > masquerading as a Microsoft Serial Mouse" problem which is quite annoying. > > > > > > > > > > > > > > > > > >> > >> 20V 5A (100W ea) on 8 ports would be 800W. That’s not going to be cheap. > >> > >> Yes, the 20V is an “optional” part of the whole thing. The 3A does not > appear > >> to be quite so easy to ignore. We’ll see what actually happens ….. > >> > >> Bob > >> > >>> On May 30, 2015, at 11:28 AM, Neil Schroeder <[email protected] > <javascript:;>> wrote: > >>> > >>> USB-C will offer a number of things that I believe will be of benefit > to > >>> time nuts everywhere: > >>> > >>> 1) High current 5V up to 3A on every port > >>> 2) High voltage/current up to 20V/5A optionally on every port - > sufficient > >>> to power some rubidium oscillators natively, and a small boost to get > the > >>> rest of them. > >>> 3) a native UART channel - no more freaky USB interrupts/polling to get > >>> your pulses > >>> 4) single omnipurpose connector ends with no insertion dependencies > >>> 5) Better, simpler device enumeration - while I haven't seen how it > >>> addresses this personally, the stuff i have read is very promising. > >>> > >>> Due to the switched controller nature of the interface, you should have > >>> less nonstandard crap that may cause your computer to hang or other > issues > >>> related to drivers. The controller arbitrates a lot more setup > details, and > >>> the number of those on the market will be limited compared to usb > >>> peripheral ICs. > >>> > >>> This may be off topic from your off topic, but it seemed a good > opportunity > >>> to share this info. > >>> > >>> NS9 > >>> _______________________________________________ > >>> time-nuts mailing list -- [email protected] <javascript:;> > >>> To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > >>> and follow the instructions there. > >> > >> _______________________________________________ > >> time-nuts mailing list -- [email protected] <javascript:;> > >> To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > >> and follow the instructions there. > >> > > > > _______________________________________________ > > time-nuts mailing list -- [email protected] <javascript:;> > > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > > and follow the instructions there. > > _______________________________________________ > time-nuts mailing list -- [email protected] <javascript:;> > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. > _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
