Although I have used them for some time I still get confused over USB ports, the different speeds and connector sizes… Does a USB Standard Size port mean that it can only run at USB 2 speed or might it it also be USB 3 speed (or 3.1)?
I am referring specifically to the two ‘large’ ports on the 10X keyboard, are they in fact speed 3— I think I have read somewhere that they are. Is this correct? I know all ports / devices are backwards compatible and that a speed 2 device will run but not at speed 3 if connected via a 3 port. I don’t think I have seen the large square ports / plugs ever described as speed 3 apart the case referred to above. Have I misread this?
If the two large ports on the keyboard are not speed 3, if I want to run speed 3 device s will I have to use the micro ports on the left edge. I have a Card Reader and a Hub which are speed 3 but have so far only used them as if they were speed 2. How can i check what speed a port is capable of?
I should note that it may be impossible for USB ports of Hi10X keyboard to supply enough power to USB devices.
It’s might be apparent because Hi10X charger capacity is 24W(2A/12V) and Hi10X+keyboard has 4 ports (USB 2.0 type-A(0.5A/5V) x2, USB 2.0 type-C(1.5~3A/5V), USB 3.0 type-C(3A/5V)). Total max. USB bus power required is 27.5W~35W. Additionally Intel Celeron N4100 requires 4.8W~6W. Even if Hi10X is connected to charger, maximum power consumption might be over 24.8~26W.
Of course, not all PCs comply with USB spec. perfectly. However bus-powered CD/DVD drive (3W) connected to Hi10X keyboard cannot work correctly (when only that device is connected)… Be careful when you use USB bus-powered devices.
Hello ---- this is an interesting post, though I do not understand the figures and calculation (something I am not strong on). When you say ‘total maximum power consumption might be etc’ does this mean when all ports are in use at the same time? If so, some devices might work if only a couple of ports (out of the 5) are in use?
I am interested in this because I have 2 devices in particular which do work now, but have needed some ‘nursing’. The most important is a USB External Hard Drive … Bipra) which I use almost exclusively for backing up important files, such as the Disk Image created by Aomei Backupper. This has two USB power sockets, one which is for power and data and one which is power only. This works fairly well especially as I do not connect the power only cable to the PC but to an external Power Hub which as well as having AC mains power sockets also has USB sockets.
The second device is an external DVD Drive (as of course Tablet PCs like ours do not come with a DVD drive). Not unexpectedly I presume as a mechanical drive, this was more difficult to get working reliably. However, again this has 2 USB ports, one power and data plus one power only which I also connect to the AC external hub. As a result it works fairly well, so I can watch DVDs including ones I made myself with a DVD camera. I did have to try several DVD drives before one finally worked.
Some external drives and USB hubs get power only supplied not via USB but though a direct cable and plug to AC. Could I be right in guessing that this arrangement would be likely to be even more successful?
I hope this might be helpful to other users who would like to try connecting an external DVD drive to a Tablet PC. It can work, but is not guaranteed to.
I have a further, related question. How common is it for devices like ours to have a 12 volt power supply? Instead of, say, 4 volt? What are the implications of this? There is a fairly lengthy discussion on this forum about one implication, which I had not realised, in that it is difficult to find a Power Bank which is compatible.
You are right. Using AC-powered USB hub is applicable for the case that some devices require much USB bus power. You perfectly grasp how USB port works.
Yes. USB is master-slave bus, that is, bi-directional signal path with one master device(usually PC) and many slave devices (keyboard, mouse …). (*)
So strictly only one of all USB devices connected to master gets command from master /or sends data to master at once. However some devices consume electric power even when they don’t get a command/send data(eg. HDD keeps spending power to spin discs). So we assume that USB should supply power to all devices all the time.
(*)only exception is ultra speed “channels” of USB3.x. In this case, signal is uni-directional and the number of signals becomes more than twice.
Power distribution through USB is really tangled because of many specifications. Especially, specifications after USB 3.x are complicated(*). As a result, some USB hub fail to negotiate device with power profile and results in temporal malfunctions.
Additionally USB Power Rule makes us confused. If you use PD1.0 device which uses 12V with PD2.0 hub, hub provides the device with 9V because of USB Power Rule. Some devices can compensate additional 3V with their switching regulator, other devices cannot. How do we solve this problem? I don’t know.
In general, high voltage has advantage in power distribution because loss by resistance of USB cable is proportional to square of current. And USB cable’s wire is not thick compared to AC adapter cable, therefore USB PD uses 9V/15V/20V(or 12V/20V).
This problem may be solved by market selection and that is a time consuming process.
(*) PD3.0 doesn’t support type-A/B connector, supports only type-C with 5V, 9V 15V, 20V. PD1.0 doesn’t support type-C, supports only type-A/B with 5V, 12V, 20V. PD2.0v1.0 supports type-A/B and type-C with 5V, 9V, 15V, 20V. Additionally USB Battery Charging (BC) specification was already published before PD. Moreover, USB has default power supply requirement(that is used to calculate power consumption in my previous reply). Finally, some PC manufacturers adopt their proprietary USB power distributions. How do we deal with these many specifications? It’s too difficult for me.
I’m personally worrying about PD2.x/3.0 power negotiation. The reason is If negotiation fails between an inappropriate USB device/cable and a USB device/cable, result may harm the device(s)/cable.
Now, Think about 2 cases:
Charge Laptop PC with USB hub.
Use USB device connected to Laptop PC.
In 1st case, USB power flows INTO PC. In 2nd case, USB power flows FROM PC. That is, the direction of USB Vbus current in (1) is opposite to in (2). This direction is determined at first by connector type (except type-C) and changed by configuration procedure between USB devices (PRS:Power Role Swap). Voltage/current of Vbus are also determined by the same configuration procedure(In this process, USB cable communicates with USB devices to tell them whether cable has capability to sink specified current. that is, In PD3.x, cable is intelligent and may limit USB function).
If power negotiation fails because of an inappropriate USB device/cable, what may happen?
Power source contention between both devices. This may harm either/both device(s)
USB I/F corruption in power sink device by too high voltage/much current
USB cable meltdown by too much current
So, I have decided that USB 2.0 type-C port of Hi10X is used only for power charger even that port has USB 2.0 data transfer capability.
How do you think about the use of USB ports which is not strictly compliant with USB spec, guys?
