Looking for the perfect hub
After analyzing the publication “ Briefly about the perfect 7-port USB 3.0 hub ORICO hub ” and comments to it, we can say that the concept of a perfect USB 3.0 hub (in short and better hub) comes down to two postulates:
Let's figure out how the model of an ideal hub is related to reality?
The requirement to charge peripherals connected to a USB hub is categorically related to the presence of external power. Today, host controllers are in most cases located on compact devices capable of operating autonomously. In this regard, the ideal situation would be when low-power tablets, laptops, smartphones shared intelligence with voracious USB peripherals, and the satisfaction of appetites would be answered by an intermediate and not a weak link in the form of a USB 3.0 hub powered by the network.
To solve this problem, the IT community proposed two specifications that are gradually being implemented with a number of reservations. This issue is well covered in online publications, in particular the applied research on the implementation of Battery Charging is set forth in the article “ Charging a tablet from USB: the question remains open .” The power supply model described in the Universal Serial Bus Power Delivery Specification is designed to provide up to 100 watts via USB. With its implementation, the situation is even worse. In fact, it’s not yet necessary to count on a current of 5 amps and a supply voltage of 20 volts from USB.
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When purchasing a USB 3.0 hub, you should take care that the purchase not only pleases the eye, but also charges everything that can be powered from the USB bus. Unfortunately, the store does not always manage to find out on which chipset the device is assembled. But even in cases where the manufacturer of the controller and its model are known, there is often not enough information about supporting the Battery Charging specification. As for USB controllers from VIA Labs, this gap is partly covered in the article “ Hub USB 3.0: the difficulty of choice ”. In a detailed analysis of the VIA controller descriptions, one detail is alarming: the documentation uses the phrase Vendor Specific Charging Modes , which refers to Apple products and RIM (read BlackBerry). There is a suspicion that not all USB hubs have this functionality - inherent quality.
Not the last value when choosing the ideal USB hub have circuit solutions. The above-mentioned article about ORICO has already focused on the fact that switching the power supply should eliminate the short circuit between the + 5V lines of the computer's USB port and the hub power supply. Equally important is the competent implementation of power circuits to ensure the required load capacity. We have already encountered this problem, getting acquainted with the features of the tablet ASUS Vivo Tab TF600T. It seems that Vendor Specific models of charging from USB expose strict requirements to the load capacity of the USB port.
As a consequence of the above, one of the requirements for an ideal USB hub should be effective current protection. It is obvious that the use of self-resetting fuses is preferable to fusible ones that require replacement after a power failure.
When choosing a USB 3.0 hub, the potential owner should be cautioned against a gross error - rely on the possibility of charging USB devices solely on the basis of the declared support for the Battery Charging specification by the hub controller. It also depends on factors not related to the functionality of the chipset: on the power supply circuits, on the content of the EPROM, on the quality of the connecting conductors and connectors, on suppression of power supply during abrupt changes in current, on the fuse ratings. But the main thing is from the implementation of the signal protocol that uses Data + lines and USB 2.0 data interfaces for organizing intelligent interaction between the charging and charging devices. And only the last factor is determined by the functionality of the hub controller chip.
In the comments to the article about ORICO, the most important issue of the functionality of a USB3 hub is raised: its ports cannot exchange data at any speed. Connecting a USB2 device reduces the exchange rate on other ports from SuperSpeed to HighSpeed.
But the requirements put forward for the independent operation of the ports of an ideal USB hub do not contradict the specifications for a universal serial bus! According to this document, a USB3 hub consists of two relatively mutually independent hubs providing USB2 and USB3 connections. The USB 3.0 specification, making an exception for a USB3 hub, unlike a conventional USB device, allows it to use USB2 and USB3 lines simultaneously. This is a prerequisite for the simultaneous operation of the HighSpeed and SuperSpeed modes.
In this regard, a quote from superuser.com , which refers to a non-trivial task of developing an independent USB3 hub model, is retorted by a quote from the original source: " Note that USB 2.0 and SuperSpeed simultaneously " :
The hub for USB 3.0 should be built on the basis of a unified software model defined as part of the Hub Class Specification. Its basic functionality should be provided before the OS is launched under the control of the firmware and other procedures that work before the device-specific drivers are loaded.
The criterion in this case should be the provision of support for the hub by the firmware within the Legacy BIOS and UEFI, the ability to boot the OS from devices connected through the ports of this hub, and the use of a keyboard or mouse in the CMOS Setup procedures.
- any USB device that requires charging can be powered by connecting to an arbitrary port on the USB hub;
- All ports of the USB hub can exchange at any speed, regardless of the status of other ports of this hub.
Let's figure out how the model of an ideal hub is related to reality?
Specifications and circuitry
The requirement to charge peripherals connected to a USB hub is categorically related to the presence of external power. Today, host controllers are in most cases located on compact devices capable of operating autonomously. In this regard, the ideal situation would be when low-power tablets, laptops, smartphones shared intelligence with voracious USB peripherals, and the satisfaction of appetites would be answered by an intermediate and not a weak link in the form of a USB 3.0 hub powered by the network.
Battery Charging Specification
To solve this problem, the IT community proposed two specifications that are gradually being implemented with a number of reservations. This issue is well covered in online publications, in particular the applied research on the implementation of Battery Charging is set forth in the article “ Charging a tablet from USB: the question remains open .” The power supply model described in the Universal Serial Bus Power Delivery Specification is designed to provide up to 100 watts via USB. With its implementation, the situation is even worse. In fact, it’s not yet necessary to count on a current of 5 amps and a supply voltage of 20 volts from USB.
')
When purchasing a USB 3.0 hub, you should take care that the purchase not only pleases the eye, but also charges everything that can be powered from the USB bus. Unfortunately, the store does not always manage to find out on which chipset the device is assembled. But even in cases where the manufacturer of the controller and its model are known, there is often not enough information about supporting the Battery Charging specification. As for USB controllers from VIA Labs, this gap is partly covered in the article “ Hub USB 3.0: the difficulty of choice ”. In a detailed analysis of the VIA controller descriptions, one detail is alarming: the documentation uses the phrase Vendor Specific Charging Modes , which refers to Apple products and RIM (read BlackBerry). There is a suspicion that not all USB hubs have this functionality - inherent quality.Circuit design power supply
Not the last value when choosing the ideal USB hub have circuit solutions. The above-mentioned article about ORICO has already focused on the fact that switching the power supply should eliminate the short circuit between the + 5V lines of the computer's USB port and the hub power supply. Equally important is the competent implementation of power circuits to ensure the required load capacity. We have already encountered this problem, getting acquainted with the features of the tablet ASUS Vivo Tab TF600T. It seems that Vendor Specific models of charging from USB expose strict requirements to the load capacity of the USB port.
As a consequence of the above, one of the requirements for an ideal USB hub should be effective current protection. It is obvious that the use of self-resetting fuses is preferable to fusible ones that require replacement after a power failure.
Risk factor
When choosing a USB 3.0 hub, the potential owner should be cautioned against a gross error - rely on the possibility of charging USB devices solely on the basis of the declared support for the Battery Charging specification by the hub controller. It also depends on factors not related to the functionality of the chipset: on the power supply circuits, on the content of the EPROM, on the quality of the connecting conductors and connectors, on suppression of power supply during abrupt changes in current, on the fuse ratings. But the main thing is from the implementation of the signal protocol that uses Data + lines and USB 2.0 data interfaces for organizing intelligent interaction between the charging and charging devices. And only the last factor is determined by the functionality of the hub controller chip.
USB 2.0 and SuperSpeed at the same time
In the comments to the article about ORICO, the most important issue of the functionality of a USB3 hub is raised: its ports cannot exchange data at any speed. Connecting a USB2 device reduces the exchange rate on other ports from SuperSpeed to HighSpeed.
But the requirements put forward for the independent operation of the ports of an ideal USB hub do not contradict the specifications for a universal serial bus! According to this document, a USB3 hub consists of two relatively mutually independent hubs providing USB2 and USB3 connections. The USB 3.0 specification, making an exception for a USB3 hub, unlike a conventional USB device, allows it to use USB2 and USB3 lines simultaneously. This is a prerequisite for the simultaneous operation of the HighSpeed and SuperSpeed modes.
In this regard, a quote from superuser.com , which refers to a non-trivial task of developing an independent USB3 hub model, is retorted by a quote from the original source: " Note that USB 2.0 and SuperSpeed simultaneously " :
USB3 hub software model
The hub for USB 3.0 should be built on the basis of a unified software model defined as part of the Hub Class Specification. Its basic functionality should be provided before the OS is launched under the control of the firmware and other procedures that work before the device-specific drivers are loaded.
The criterion in this case should be the provision of support for the hub by the firmware within the Legacy BIOS and UEFI, the ability to boot the OS from devices connected through the ports of this hub, and the use of a keyboard or mouse in the CMOS Setup procedures.
Source: https://habr.com/ru/post/233781/
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