Universal Serial Bus (USB)

00:39:04
https://www.youtube.com/watch?v=RxuM2eHy5vI

Résumé

TLDREl vídeo explora el bus sèrie universal (USB), un estàndard que permet la connexió de diversos dispositius a ordinadors. Es discuteix la seva història, des de la seva introducció el 1996 per substituir els connectors PS/2, fins a les seves versions actuals. El funcionament del USB es basa en un controlador host que gestiona la comunicació amb els dispositius connectats. Es destaca la importància de la potència i l'amplada de banda, així com les limitacions en la cadena de dispositius USB. També es presenten les diferències entre hubs alimentats i no alimentats, i es detallen les versions de USB, incloent la seva compatibilitat i velocitats de transferència.

A retenir

  • 🔌 USB és un estàndard per a la connexió de perifèrics.
  • 📅 Va ser llançat el 1996 per substituir el PS/2.
  • 📊 Un controlador USB pot suportar fins a 127 dispositius.
  • 🖥️ Els hubs USB permeten expandir connexions.
  • ⚡ Hi ha hubs alimentats i no alimentats.
  • 📏 La longitud màxima dels cables USB varia segons la versió.
  • 🔄 USB On-The-Go permet que els dispositius actuïn com a mestres o esclaus.
  • 📈 L'amplada de banda afecta la velocitat de transferència.
  • 🔄 USB és retrocompatible amb versions anteriors.
  • 🧩 Les diferents versions de USB tenen velocitats i connectors diferents.

Chronologie

  • 00:00:00 - 00:05:00

    En aquest vídeo, es presenta el bus sèrie universal (USB), que va ser llançat el 1996 per connectar perifèrics i dispositius. Es destaca la importància de comprendre el funcionament de l'USB per als tècnics informàtics, ja que és essencial per a la connexió de diversos dispositius com impressores i mòbils. A més, es menciona que l'USB és 'hot swappable' i 'auto configurable', facilitant la seva utilització sense necessitat de reiniciar l'ordinador.

  • 00:05:00 - 00:10:00

    El controlador d'host USB és el nucli del sistema USB, proporcionant una interfície per comunicar-se amb el maquinari. Cada controlador d'host pot suportar fins a 127 dispositius, tot i que en la pràctica és poc probable que s'arribi a aquest límit. Els hubs USB permeten expandir un port USB en múltiples ports, facilitant la connexió de diversos dispositius.

  • 00:10:00 - 00:15:00

    Els hubs USB poden ser independents o integrats en altres dispositius. Es discuteix la limitació de potència en els hubs USB, ja que un port USB pot proporcionar entre 100 i 500 mA. Això significa que un hub bàsic amb quatre ports pot estar limitat a 500 mA, i si es connecten dispositius que requereixen més potència, poden no funcionar correctament.

  • 00:15:00 - 00:20:00

    Es destaca que l'USB utilitza paquets per transmetre dades i que la seva arquitectura pot provocar problemes de banda ampla si es connecten dispositius d'alta demanda en ports que comparteixen la mateixa amplada de banda. El controlador d'host USB gestiona la comunicació entre dispositius, assegurant que no hi hagi conflictes en la transmissió de dades.

  • 00:20:00 - 00:25:00

    Es presenta l'arquitectura USB, que inclou el controlador d'host, el hub arrel i els ports USB. Es discuteix la importància de la potència i la limitació de ports en els hubs no alimentats, així com la possibilitat d'afegir més dispositius mitjançant hubs alimentats per evitar problemes de potència.

  • 00:25:00 - 00:30:00

    Es revisen les diferents versions d'USB, incloent USB 1.1, 2.0, 3.0, 3.1 i 3.2, amb les seves velocitats respectives. Es menciona la compatibilitat entre versions, així com les confusions que poden sorgir amb els noms de màrqueting i les denominacions de les versions.

  • 00:30:00 - 00:39:04

    Finalment, es discuteix la compatibilitat entre dispositius USB de diferents velocitats i la importància de la longitud del cable. S'explica com els dispositius USB poden funcionar com a mestres o esclaus, i es presenten els connectors USB, incloent el tipus C, que permet una connexió bidireccional.

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Carte mentale

Vidéo Q&R

  • Què és el USB?

    El bus sèrie universal (USB) és un estàndard per a la connexió de perifèrics i dispositius a ordinadors.

  • Quina és la història del USB?

    El USB va ser llançat el 1996 per substituir els connectors PS/2.

  • Quants dispositius pot suportar un controlador USB?

    Un controlador USB pot suportar un màxim de 127 dispositius.

  • Què és un hub USB?

    Un hub USB permet expandir una connexió USB en múltiples connexions.

  • Quines són les versions de USB més comunes?

    Les versions més comunes són USB 1.1, USB 2.0, USB 3.0, USB 3.1 i USB 3.2.

  • Quina és la diferència entre hubs USB alimentats i no alimentats?

    Els hubs alimentats proporcionen potència externa als dispositius, mentre que els no alimentats depenen de la potència del port USB.

  • Quina és la longitud màxima dels cables USB?

    La longitud màxima és de 3 metres per a USB 1, 5 metres per a USB 2, i es recomana que els cables USB 3 no superin els 3 metres.

  • Què és USB On-The-Go?

    USB On-The-Go permet que un dispositiu funcioni com a mestre o esclau.

  • Quina és la importància de l'amplada de banda en USB?

    L'amplada de banda determina la velocitat de transferència de dades entre dispositius USB.

  • Com es gestiona la compatibilitat entre diferents versions de USB?

    USB és retrocompatible, de manera que els dispositius USB 1.1 funcionen en ports USB 2.0 i USB 3.0.

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Sous-titres
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  • 00:00:00
    in this video for my tea free training I
  • 00:00:02
    will look at the Universal Serial bus or
  • 00:00:05
    USB USB standardized the connections to
  • 00:00:09
    peripherals and has become very popular
  • 00:00:11
    due to its popularity it is essential
  • 00:00:14
    for the IT technician to have a good
  • 00:00:16
    understanding of how USB works Universal
  • 00:00:21
    Serial bus or USB was released in 1996
  • 00:00:24
    it provides connectors and cables to
  • 00:00:27
    connect peripherals and devices USB was
  • 00:00:30
    originally designed to replace the ps2
  • 00:00:33
    plug which was used for the keyboard and
  • 00:00:35
    mouse the ps/2 connector was limited to
  • 00:00:38
    only being able to be used for keyboard
  • 00:00:41
    and mouse USB was designed to support
  • 00:00:43
    any device that was manufactured to be
  • 00:00:45
    compatible with USB for example USB
  • 00:00:49
    could be used for USB sticks connecting
  • 00:00:51
    printers or even your mobile device USB
  • 00:00:56
    was designed to be hot swappable this
  • 00:00:58
    means that you can connect and
  • 00:01:00
    disconnect devices from your computer
  • 00:01:02
    without rebooting the computer USB is
  • 00:01:06
    also Auto configurable in the old days
  • 00:01:08
    of computing interrupts ports and other
  • 00:01:11
    settings would need to be configured
  • 00:01:12
    however with USB the resources the
  • 00:01:15
    device requires are automatically
  • 00:01:17
    allocated nowadays USB has become very
  • 00:01:20
    popular and it would be hard to find a
  • 00:01:23
    computer that does not have at least one
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    USB port USB is used to connect every
  • 00:01:28
    device you could think of to your
  • 00:01:29
    computer let's have a look at how it
  • 00:01:32
    works
  • 00:01:34
    at the heart of USB is the USB host
  • 00:01:37
    controller the USB host controller
  • 00:01:40
    provides an interface to communicate
  • 00:01:42
    with the hardware each host controller
  • 00:01:45
    has one root hub regardless of how many
  • 00:01:48
    USB controllers you have the operating
  • 00:01:50
    system will communicate with the USB
  • 00:01:52
    controller using a standard interface in
  • 00:01:55
    this example there is one chip in the
  • 00:01:58
    computer that provides a USB host
  • 00:02:00
    controller nowadays the USB host
  • 00:02:03
    controller will not be a separate chip
  • 00:02:05
    but will most likely be found in the
  • 00:02:07
    Northbridge in some motherboards the
  • 00:02:11
    newer faster USB 3 controller
  • 00:02:13
    would be found in the Northbridge and
  • 00:02:15
    the older slower USB controller would be
  • 00:02:18
    found in the Southbridge I will look at
  • 00:02:21
    the different versions of USB later in
  • 00:02:24
    the video regardless of how many USB
  • 00:02:27
    controllers you have on your motherboard
  • 00:02:28
    their versions and if they are on one
  • 00:02:31
    chip or more they essentially work the
  • 00:02:33
    same way
  • 00:02:34
    each USB host controller can support a
  • 00:02:38
    maximum of 127 devices in the real world
  • 00:02:42
    it is unlikely this maximum will be
  • 00:02:44
    reached for a number of reasons which I
  • 00:02:46
    will look at later in the video to
  • 00:02:48
    manage a large number of devices using
  • 00:02:50
    the one USB controller each USB
  • 00:02:53
    controller has one or more route ups in
  • 00:02:56
    this example you can see the USB host
  • 00:02:59
    controller is connected to the root hub
  • 00:03:02
    the root hub is then connected to the
  • 00:03:04
    physical USB ports the USB host
  • 00:03:08
    controller may support more physical
  • 00:03:10
    ports than what are available on the
  • 00:03:12
    motherboard it is up to the manufacturer
  • 00:03:14
    of the motherboard to determine how many
  • 00:03:16
    physical ports they are going to support
  • 00:03:19
    now you may be thinking if one
  • 00:03:21
    controller can potentially support 127
  • 00:03:24
    devices there are no motherboards on the
  • 00:03:27
    market that have anywhere close to 127
  • 00:03:30
    USB connectors there are motherboards
  • 00:03:33
    that have 16 USB connectors which should
  • 00:03:36
    be enough so let's have a look at why
  • 00:03:39
    you would need to support so many USB
  • 00:03:43
    has the ability for one port to be
  • 00:03:45
    expanded to many ports this is the same
  • 00:03:48
    principle as a power strip shown here is
  • 00:03:51
    a USB hub this USB hub allows one USB
  • 00:03:55
    connection to be split into four
  • 00:03:58
    connections USB hubs can be separate
  • 00:04:00
    devices like this one or can be included
  • 00:04:03
    in devices like computer monitors and
  • 00:04:05
    keyboards the USB hub has an input port
  • 00:04:09
    which is referred to as an up stream
  • 00:04:11
    port this will be connected directly to
  • 00:04:14
    the computer or another USB hub in the
  • 00:04:18
    case of this USB hub there are four
  • 00:04:20
    downstream ports which devices or other
  • 00:04:23
    USB hubs can be connected to
  • 00:04:26
    in this case a USB thumb drive is
  • 00:04:29
    connected to one of the ports another
  • 00:04:31
    one of the ports is connected to a
  • 00:04:32
    second hub in a previous video we looked
  • 00:04:36
    at what would happen if you connected
  • 00:04:37
    multiple power strips together let's
  • 00:04:40
    have a look at the problem that may
  • 00:04:41
    occur if you connect multiple USB hubs
  • 00:04:43
    together USB is designed to allow up to
  • 00:04:47
    five tears in this case you can see that
  • 00:04:51
    I've connected four USB hubs together
  • 00:04:54
    when I did this the computer was able to
  • 00:04:57
    access the USB stick plugged into the
  • 00:04:59
    last USB hub the point to remember is
  • 00:05:02
    that the computer contains a root hub
  • 00:05:05
    this root hub is essentially the first
  • 00:05:07
    hub in the chain so essentially this
  • 00:05:10
    means that a maximum of four USB hubs
  • 00:05:12
    can be added the one inside the computer
  • 00:05:15
    plus four additional ones making a total
  • 00:05:18
    of five the USB officially supports five
  • 00:05:21
    tiers but this may or may not work I
  • 00:05:24
    would not recommend daisy chaining USB
  • 00:05:28
    hubs together like this computers
  • 00:05:30
    nowadays come with a lot of USB
  • 00:05:32
    connectors if you need more USB
  • 00:05:34
    connectors then you increase the number
  • 00:05:36
    with a USB hub if you need two or more
  • 00:05:39
    USB hubs consider plugging each USB hub
  • 00:05:43
    into different USB ports rather than
  • 00:05:45
    daisy chaining them together let's have
  • 00:05:48
    a closer look at how USB works and thus
  • 00:05:51
    why we may have problems daisy chaining
  • 00:05:54
    devices together the first problem you
  • 00:05:57
    may encounter when daisy chaining USB
  • 00:05:59
    devices together is power a single USB
  • 00:06:03
    port on your computer will supply 100 to
  • 00:06:05
    500 milliamps of power essentially when
  • 00:06:08
    you plug devices into your computer the
  • 00:06:11
    device will use a minimum of 100
  • 00:06:13
    milliamps but can draw up to 500
  • 00:06:16
    milliamps if it requires it the device
  • 00:06:19
    that is used will determine how much
  • 00:06:21
    power it will require devices that do
  • 00:06:24
    not have an external power supply will
  • 00:06:26
    most likely require more power for
  • 00:06:29
    example a USB hard disk that draws power
  • 00:06:31
    from the USB is most likely going to use
  • 00:06:34
    more power than a USB stick as it needs
  • 00:06:36
    power to spin the hard disk platters
  • 00:06:39
    now let's consider what happens when you
  • 00:06:41
    use a USB hub like before the USB can
  • 00:06:45
    draw up to 500 milliamps of power from
  • 00:06:47
    the computer in order to power the USB
  • 00:06:50
    hub 100 milliamps are required each port
  • 00:06:54
    will use a further 100 milliamps this
  • 00:06:57
    essentially means that a basic USB hub
  • 00:07:00
    is limited to 4 ports as power is
  • 00:07:02
    divided up as follows 100 milliamps for
  • 00:07:05
    the hub 100 milliamps for each port
  • 00:07:08
    making 400 which is a total of 500
  • 00:07:11
    milliamps you may remember from a
  • 00:07:14
    previous video we looked at what would
  • 00:07:16
    happen if you combine multiple power
  • 00:07:18
    strips together
  • 00:07:19
    however unlike power strips USB will not
  • 00:07:22
    draw more power than the maximum amount
  • 00:07:25
    so by combining multiple USB hubs
  • 00:07:28
    together you won't risk overloading the
  • 00:07:30
    power in the computer what then happens
  • 00:07:33
    when you plug in a device that requires
  • 00:07:34
    more power than the USB hub can deliver
  • 00:07:37
    unlike a power strip which will draw
  • 00:07:40
    more power and potentially overload a
  • 00:07:41
    circuit a USB device will simply not
  • 00:07:44
    work the operating system you are using
  • 00:07:47
    will give you a message telling you
  • 00:07:49
    there is not enough power to operate the
  • 00:07:51
    device so how do we get around the power
  • 00:07:55
    issue while also being able to use a USB
  • 00:07:57
    hub with more than 4 ports when
  • 00:08:00
    purchasing a hub you can choose from
  • 00:08:02
    powered and non power a powered hub
  • 00:08:05
    supplies power to its ports from
  • 00:08:07
    external power powered hubs cost more
  • 00:08:10
    than non powered hubs a powered hub
  • 00:08:13
    generally will be plugged into a power
  • 00:08:15
    plug but it could be powered in other
  • 00:08:18
    ways for example a hub inside a monitor
  • 00:08:21
    will draw its power from the monitor you
  • 00:08:24
    can see in this example the power plug
  • 00:08:26
    is at the top of the hub this supplies
  • 00:08:29
    power to the hub and is used to provide
  • 00:08:31
    power to each of the downstream ports on
  • 00:08:33
    the hub depending on the hub the power
  • 00:08:36
    delivered to each port can be between
  • 00:08:38
    100 to 500 milliamps the better hubs
  • 00:08:42
    will be able to deliver 500 milliamps to
  • 00:08:44
    all ports cheaper hubs may only be able
  • 00:08:47
    to deliver 500 milliamps to a few ports
  • 00:08:49
    and then the output will be reduced
  • 00:08:52
    for the other ports for this reason it
  • 00:08:55
    is important to check the packaging
  • 00:08:56
    before buying a hub to make sure it will
  • 00:08:58
    deliver full power to all ports the hub
  • 00:09:02
    will be connected to the computer or
  • 00:09:04
    another USB hub via a single upstream
  • 00:09:07
    connection if there is a problem
  • 00:09:10
    powering a device on the hub the
  • 00:09:12
    computer should give you a message
  • 00:09:13
    indicating this when this occurs check
  • 00:09:16
    your hub is powered most likely the
  • 00:09:19
    power plug has come out or the hub
  • 00:09:20
    cannot provide enough power to power the
  • 00:09:22
    device the downside of using a USB hub
  • 00:09:27
    is that since the hub is always powered
  • 00:09:29
    this can cause devices connected to it
  • 00:09:32
    to also be always powered up for example
  • 00:09:35
    a hard disk connected to a USB powered
  • 00:09:37
    hub will always be powered up even if
  • 00:09:40
    the computer is not switched on some
  • 00:09:43
    devices will go into standby if not used
  • 00:09:45
    for a period of time this is something
  • 00:09:47
    to consider when plugging a device into
  • 00:09:49
    a USB powered hub or you can switch off
  • 00:09:53
    the power hub when you switch off the
  • 00:09:54
    computer if you leave the USB hub on and
  • 00:09:58
    if the device does not go into standby
  • 00:10:00
    it may keep operating
  • 00:10:03
    even when the computer is switched off
  • 00:10:05
    the next thing to consider with USB is
  • 00:10:08
    bandwidth the USB uses packets to
  • 00:10:12
    transmit data it works in a similar way
  • 00:10:14
    the hell networks transmit packets if
  • 00:10:17
    you consider a USB controller as I
  • 00:10:20
    covered in a previous video it is
  • 00:10:22
    connected to one or more USB root hub
  • 00:10:26
    each USB root hub can be connected to
  • 00:10:29
    one or more ports in this example this
  • 00:10:32
    root hub is connected to two USB ports
  • 00:10:35
    what this means is that essentially the
  • 00:10:37
    bandwidth from this root hub is shared
  • 00:10:40
    between two ports if you have high
  • 00:10:43
    bandwidth on one port and a low
  • 00:10:45
    bandwidth device on the other this will
  • 00:10:47
    not be a problem however if you put a
  • 00:10:50
    high bandwidth device on both ports this
  • 00:10:53
    can cause bandwidth problems now
  • 00:10:56
    consider what happens when you install a
  • 00:10:58
    USB hub the USB hub has four ports which
  • 00:11:02
    increases the number of ports connected
  • 00:11:04
    directly or indoor
  • 00:11:05
    Klee to the root hub to five this
  • 00:11:08
    essentially means that a port on the USB
  • 00:11:10
    hub can use almost all the bandwidth
  • 00:11:13
    more on that in a moment or limited to
  • 00:11:16
    one-fifth of the bandwidth it all
  • 00:11:18
    depends on how much bandwidth the other
  • 00:11:20
    devices are using which will determine
  • 00:11:22
    how much bandwidth that port will get
  • 00:11:25
    USB uses a token method for packet
  • 00:11:28
    transmission what happens is the host
  • 00:11:31
    sends out a token to each device to let
  • 00:11:33
    it know it can communicate if you are
  • 00:11:36
    familiar with the old token based
  • 00:11:37
    networks you know the devices on the
  • 00:11:40
    network controlled a single token moving
  • 00:11:42
    around the network if a device had the
  • 00:11:44
    token it knows it could send data on the
  • 00:11:47
    network the problem occurred when the
  • 00:11:49
    token was lost and a new one would need
  • 00:11:51
    to be created sometimes a second token
  • 00:11:54
    would be created and there would be two
  • 00:11:56
    tokens on the network then two devices
  • 00:11:58
    would try and transmit at once
  • 00:12:01
    USB gets around this problem by the USB
  • 00:12:04
    host controller sending out a token to
  • 00:12:06
    each device thus the USB host controller
  • 00:12:10
    always has control over who is sending
  • 00:12:12
    and receiving data if you have more
  • 00:12:15
    devices on the same USB controller this
  • 00:12:17
    is more devices the USB controller has
  • 00:12:20
    to send tokens to you can see why you
  • 00:12:23
    may not get the full bandwidth because
  • 00:12:26
    USB has to use some of the bandwidth to
  • 00:12:28
    check the other devices to make sure
  • 00:12:30
    they do not wish to send data even
  • 00:12:32
    though this is a small amount of time
  • 00:12:34
    this method also stops one device taking
  • 00:12:37
    all the bandwidth and allows the
  • 00:12:39
    bandwidth to be better shared between
  • 00:12:41
    devices a USB device also has the option
  • 00:12:44
    to go into standby mode if it is not
  • 00:12:46
    being used and thus will not receive any
  • 00:12:48
    tokens until it comes out of standby
  • 00:12:51
    when connecting devices to a computer
  • 00:12:54
    bandwidth is something I will always
  • 00:12:55
    consider for example for a capture card
  • 00:12:58
    that requires a lot of bandwidth
  • 00:13:00
    I will generally have it plug directly
  • 00:13:02
    into the computer rather than connected
  • 00:13:05
    to a USB hub although some computers
  • 00:13:08
    will only have the one USB root hub if
  • 00:13:11
    your computer has multiple root ups it
  • 00:13:14
    is worth connecting different devices to
  • 00:13:16
    different root hubs
  • 00:13:18
    if I'm not sure generally I will plug
  • 00:13:20
    two high-bandwidth devices away from
  • 00:13:23
    each other for example plug one into the
  • 00:13:26
    front of the case and one in the back
  • 00:13:28
    otherwise plug both in the back of the
  • 00:13:30
    case but away from each other
  • 00:13:32
    generally speaking USB ports that are
  • 00:13:35
    next to each other are more likely to be
  • 00:13:37
    on the same root hub to put everything I
  • 00:13:41
    have covered so far into perspective I
  • 00:13:43
    will now have a look at the USB
  • 00:13:45
    architecture at the top you have your
  • 00:13:48
    host essentially the computer that is
  • 00:13:51
    providing USB functions this is called
  • 00:13:53
    the USB host controller it may be on its
  • 00:13:57
    own chip but generally it will be
  • 00:13:59
    included inside another chip that
  • 00:14:01
    provides USB functions on some
  • 00:14:03
    motherboards there may be two or more
  • 00:14:05
    USB host controllers the USB host
  • 00:14:09
    controller contains the root hub the
  • 00:14:11
    root hub essentially performs the same
  • 00:14:13
    functions as a USB hub connected
  • 00:14:15
    physically to the computer it allows one
  • 00:14:18
    or more USB ports to be connected to the
  • 00:14:21
    computer
  • 00:14:21
    this essentially forms the second-tier
  • 00:14:24
    as the root hub is the first tier to
  • 00:14:28
    increase the number of USB ports a USB
  • 00:14:30
    hub can be used this allows another tier
  • 00:14:33
    of USB devices to be used for example
  • 00:14:36
    more USB hubs or devices when you start
  • 00:14:40
    getting down to tier 2 you will most
  • 00:14:42
    likely start having some power problems
  • 00:14:45
    unless you are using a powered USB hub
  • 00:14:48
    the computer will output 500 milliamps
  • 00:14:51
    of power remember that each USB port and
  • 00:14:54
    hub requires a minimum of 100 milliamps
  • 00:14:57
    of power as soon as the number of
  • 00:14:59
    outgoing ports on a USB hub gets above 4
  • 00:15:02
    you are going to have power problems
  • 00:15:05
    remember the incoming port also requires
  • 00:15:07
    power which makes five ports at 100
  • 00:15:10
    milliamps for a total of 500 milliamps
  • 00:15:13
    this effectively limits the number of
  • 00:15:15
    ports on a USB hub to 4 if it is not
  • 00:15:18
    powered you are free if you wish to add
  • 00:15:20
    more devices in hubs if you so choose to
  • 00:15:23
    form another tier most users won't have
  • 00:15:25
    a need to do this but later in the video
  • 00:15:27
    I will look into an example where it is
  • 00:15:29
    a useful feature to have
  • 00:15:31
    lastly you have tier 5 if you really
  • 00:15:35
    need to you can add more devices to this
  • 00:15:38
    tier in testing I have added hubs to
  • 00:15:41
    this tier and it worked
  • 00:15:42
    however if you start daisy chaining too
  • 00:15:45
    many devices together you can't expect
  • 00:15:47
    it to work you may or may not get lucky
  • 00:15:50
    if you try to do this the power problems
  • 00:15:53
    should be easy to solve using powered
  • 00:15:55
    hubs however when you start getting down
  • 00:15:58
    to this number of tiers it means more
  • 00:16:00
    devices that traffic needs to go through
  • 00:16:02
    and more things that can go wrong if you
  • 00:16:06
    need to connect a lot of devices I would
  • 00:16:08
    personally attempt to use fewer tiers
  • 00:16:10
    rather than more you can purchase a USB
  • 00:16:14
    hub with 7 ports this may seem a better
  • 00:16:16
    option than using USB hubs however as we
  • 00:16:19
    will see later in the video a 7 port USB
  • 00:16:22
    hub can be essentially two USB hubs
  • 00:16:25
    connected together USB has different
  • 00:16:28
    versions which run at different speeds
  • 00:16:30
    now that we understand how we could
  • 00:16:33
    connect devices together let's see what
  • 00:16:35
    happens when we connect devices of
  • 00:16:37
    different speeds together before we can
  • 00:16:39
    do that however we first need to
  • 00:16:41
    understand the different versions of USB
  • 00:16:44
    there have been a lot of different
  • 00:16:46
    versions of USB over the years not all
  • 00:16:48
    were adopted so I will only cover the
  • 00:16:50
    commonly used ones the first widely
  • 00:16:53
    adopted version of USB was 1.1 USB 1.1
  • 00:16:58
    supports a high and low speed mode high
  • 00:17:01
    speed mode runs at 12 megabits per
  • 00:17:03
    second and low speed runs at 1.5
  • 00:17:06
    megabits per second although you won't
  • 00:17:09
    be able to purchase a computer that has
  • 00:17:11
    a USB 1.1 port USB 1.1 devices are still
  • 00:17:15
    sold on the market devices like a
  • 00:17:18
    keyboard or mouse don't need to send a
  • 00:17:21
    lot of data and thus don't need to run
  • 00:17:23
    at high speed these devices still use
  • 00:17:25
    USB 1.1 the next USB standard was
  • 00:17:29
    version 2 released in the year 2000
  • 00:17:32
    these used the same connectors as USB
  • 00:17:34
    one and so are backward compatible this
  • 00:17:37
    is why there can still be USB 1.1
  • 00:17:40
    devices on the market even though USB
  • 00:17:43
    1.1 ports are no long
  • 00:17:45
    produced USB to increase the speed to
  • 00:17:48
    480 megabits per second this is a fairly
  • 00:17:52
    decent speed for a lot of devices so you
  • 00:17:54
    will find the devices like keyboards
  • 00:17:56
    mice and headphones use the USB to
  • 00:17:59
    standard this is unlikely to change
  • 00:18:01
    anytime soon
  • 00:18:03
    the next version released was USB 3 this
  • 00:18:07
    was released in the year 2008 this
  • 00:18:09
    increased the speed to five gigabits per
  • 00:18:11
    second to get this increased speed the
  • 00:18:14
    SuperSpeed type a connector is required
  • 00:18:17
    the connector is generally blue in color
  • 00:18:20
    so it is easy to tell apart from the USB
  • 00:18:22
    1 and 2 connectors if you have the right
  • 00:18:25
    connector it will run at USB 3 speed
  • 00:18:28
    otherwise it will run at USB 2 speed the
  • 00:18:32
    next version released was USB 3.1 this
  • 00:18:36
    was released in 2013
  • 00:18:37
    the version runs at 10 gigabits per
  • 00:18:40
    second like before to get the higher
  • 00:18:43
    speed you need the SuperSpeed type-a
  • 00:18:45
    connector this version however does
  • 00:18:48
    support the type-c connector this
  • 00:18:51
    connector unlike any of the other USB
  • 00:18:53
    connectors can be inserted in any
  • 00:18:55
    direction you don't have to worry about
  • 00:18:58
    it being plugged being upside down as it
  • 00:19:00
    will work regardless of which way it is
  • 00:19:02
    plugged in the last version I will look
  • 00:19:05
    at is USB 3.2 released in 2017 this
  • 00:19:10
    increases the speed to 20 gigabits per
  • 00:19:12
    second in order to get this speed
  • 00:19:14
    however you need to use the type-c
  • 00:19:16
    connector the type-c connector has an
  • 00:19:19
    additional data line without this extra
  • 00:19:21
    data line USB 3.2 cannot get the extra
  • 00:19:25
    speed so this is why the SuperSpeed
  • 00:19:27
    connectors will be backward compatible
  • 00:19:28
    but it will not run at 20 gigabits per
  • 00:19:31
    second I think the different USB
  • 00:19:34
    versions are pretty easy to understand
  • 00:19:36
    so let's have a look at how
  • 00:19:38
    manufacturers have made some changes to
  • 00:19:40
    make things really confusing this
  • 00:19:43
    information you don't need to know for
  • 00:19:45
    the CompTIA exam however if you are
  • 00:19:47
    purchasing USB products it is good to
  • 00:19:50
    know so essentially what happened is
  • 00:19:52
    there have been a number of name changes
  • 00:19:54
    to USB 3 to start with
  • 00:19:57
    USB 3.0 is also called USB 3.1 gen
  • 00:20:05
    they then decided to change the name to
  • 00:20:07
    USB 3.2 gen 1 so if you purchase a
  • 00:20:11
    motherboard which has USB 3.2 Gen 1
  • 00:20:14
    ports this essentially means that it is
  • 00:20:17
    a USB 3.0 port to make things more
  • 00:20:20
    complicated the marketing name used was
  • 00:20:23
    3.0 super speed USB 4 USB 3.0 so if you
  • 00:20:29
    purchase a USB device you may see it
  • 00:20:32
    called super speed USB rather than USB
  • 00:20:35
    3.0 confused yet I would suggest
  • 00:20:39
    referencing this table if you were
  • 00:20:40
    buying a USB device so you know what you
  • 00:20:43
    were buying as the name could be any one
  • 00:20:46
    of those listed to make things more
  • 00:20:49
    complicated USB 3.1 was also called USB
  • 00:20:53
    3.1 gen2 this later changed to USB 3.2
  • 00:20:58
    gen 2 the marketing name however is
  • 00:21:01
    super speed USB 10 gigabits for the
  • 00:21:05
    CompTIA exam you only need to know the
  • 00:21:07
    version numbers that is version 3 3.1
  • 00:21:11
    and 3.2 lastly USB 3.2 was changed to
  • 00:21:17
    USB 3.2 Gen 2 by 2 this is because it
  • 00:21:23
    has two data lanes so the name
  • 00:21:25
    references this fact
  • 00:21:26
    lastly the marketing name for this is
  • 00:21:29
    super speed USB 20 gigabits per second
  • 00:21:33
    you will
  • 00:21:34
    happy to know that this is the last time
  • 00:21:36
    that I will reference this table in this
  • 00:21:38
    course I will simply use the names USB 3
  • 00:21:42
    USB 3.1 and USB three-point 2 for the
  • 00:21:46
    CompTIA this is all you need to know the
  • 00:21:50
    only time you will need reference this
  • 00:21:51
    information is when you purchase a
  • 00:21:53
    device or when buying the motherboard
  • 00:21:55
    till you know what you are purchasing
  • 00:21:57
    the next topic I will look at is
  • 00:22:00
    compatibility the USB 2 is backward
  • 00:22:03
    compatible with USB 1 if you plug a USB
  • 00:22:06
    1 device into a USB 2 port it will work
  • 00:22:10
    USB 3 devices are backward compatible
  • 00:22:13
    with USB 2 when I say USB 3 I mean 3.0
  • 00:22:17
    3.1 and 3.2 that is all the different
  • 00:22:21
    versions of USB 3 since USB 2 is
  • 00:22:24
    compatible with USB 1 then USB 3 is also
  • 00:22:27
    compatible with USB 1 to get the max
  • 00:22:31
    speed you will require the super speed
  • 00:22:33
    or type-c cable if you plug in a USB 2
  • 00:22:38
    cable it will still work you just won't
  • 00:22:41
    get the max speed you may find that some
  • 00:22:44
    USB 3 devices won't work with USB 2 this
  • 00:22:47
    won't be a hardware problem it will be a
  • 00:22:49
    problem with the software for example
  • 00:22:51
    digital capture devices require a lot of
  • 00:22:54
    bandwidth and the software won't work
  • 00:22:57
    with USB 2 because it is not fast enough
  • 00:22:59
    this won't prevent the device from
  • 00:23:01
    installing but when you run the software
  • 00:23:03
    it will say it needs the extra speed of
  • 00:23:06
    USB 3 to work in most cases you will
  • 00:23:09
    find the device will still work it will
  • 00:23:11
    just run at a lower speed to summarize
  • 00:23:15
    USB is backward compatible if you are
  • 00:23:19
    using the wrong cable it will still work
  • 00:23:20
    but the speed will be lower next I'll
  • 00:23:24
    have a look at how USB supports
  • 00:23:26
    compatibility to understand how USB
  • 00:23:28
    handles different versions consider this
  • 00:23:31
    route up that is connected to four
  • 00:23:32
    physical ports the route has USB 2 and
  • 00:23:36
    USB 3 ports attached to it on the first
  • 00:23:39
    port a keyboard is attached the port is
  • 00:23:42
    a USB 2 port the keyboard is a USB 1.1
  • 00:23:46
    device
  • 00:23:47
    so the port will set its speed to USB
  • 00:23:49
    1.1 the next port has a USB stick that
  • 00:23:54
    supports USB 2 for this reason the USB 2
  • 00:23:58
    port will run at USB 2 speed the next
  • 00:24:02
    port is USB 3 which has a USB 2 storage
  • 00:24:06
    device attached so the port will run at
  • 00:24:09
    USB 2 speed
  • 00:24:11
    the last port is USB 3 and has a USB 3
  • 00:24:15
    mobile device attached so it will run at
  • 00:24:18
    USB 3 speed so essentially the port has
  • 00:24:22
    matched the speed of the device attached
  • 00:24:24
    if you are familiar with networking this
  • 00:24:27
    is the same principle when you plug a
  • 00:24:28
    network card into a network switch the
  • 00:24:31
    network switch will change the speed of
  • 00:24:33
    the port to match the network card that
  • 00:24:35
    is attached like network equipment the
  • 00:24:38
    root hub uses a buffer the buffer is
  • 00:24:41
    what allows the port to run at different
  • 00:24:43
    speeds remember that a root hub has a
  • 00:24:46
    single upstream port the buffer is used
  • 00:24:49
    to manage the different speeds so the
  • 00:24:51
    data can be packaged into the upstream
  • 00:24:53
    port this is a little different from a
  • 00:24:56
    networking device as the root hub pulls
  • 00:24:58
    the device and tells it when to transmit
  • 00:25:01
    a network device in contrast cannot
  • 00:25:04
    control this however it can ask a device
  • 00:25:06
    to slow down if it is transmitting too
  • 00:25:08
    fast so far we have looked at USB in a
  • 00:25:13
    master slave configuration that is the
  • 00:25:15
    computer or the root hub is the master
  • 00:25:17
    device with slave devices attached
  • 00:25:20
    however this may not always be the case
  • 00:25:23
    before I look at how this is achieved
  • 00:25:25
    I will first have a look at the
  • 00:25:27
    different connector types used by USB
  • 00:25:30
    the first type is the master connection
  • 00:25:33
    type the second type is the slave
  • 00:25:35
    connection devices like keyboards and
  • 00:25:38
    mice use these kinds of connections
  • 00:25:40
    because they never need to access other
  • 00:25:42
    devices the device is essentially a
  • 00:25:45
    slave device which is controlled by the
  • 00:25:47
    device it is plugged into the most
  • 00:25:50
    common connection is the type a
  • 00:25:52
    connection this supports USB 1 or USB 2
  • 00:25:56
    having a different plug means it cannot
  • 00:25:58
    be plugged in the wrong way
  • 00:26:00
    the plug itself is quite large so not
  • 00:26:03
    practical for smaller devices for this
  • 00:26:05
    reason the mini plug and the micro plug
  • 00:26:08
    were created these plugs were smaller
  • 00:26:11
    and thus useful for smaller devices like
  • 00:26:13
    mobile devices and cameras both support
  • 00:26:16
    USB one or two
  • 00:26:17
    the plugs essentially used the same
  • 00:26:19
    wires in the cable and do not change
  • 00:26:21
    only the shape of the plug changes for
  • 00:26:25
    this reason any of the master plugs can
  • 00:26:27
    be connected to the slave blocks with
  • 00:26:30
    the introduction of USB 3 more wires
  • 00:26:33
    were needed however it was desirable to
  • 00:26:35
    be compatible with USB 2 thus a
  • 00:26:38
    connection was designed that was the
  • 00:26:40
    same size and shape as USB 2 however
  • 00:26:42
    contained more wires inside if a USB to
  • 00:26:46
    device was plugged into a USB 3 plug it
  • 00:26:49
    would not have all the connections and
  • 00:26:51
    thus only use the USB 2 wires
  • 00:26:54
    thus USB 2 and USB 3 were compatible
  • 00:26:58
    with each other of course if you connect
  • 00:27:01
    a USB 2 to USB 3 the speed will drop
  • 00:27:04
    although USB 3 can use the micro and
  • 00:27:07
    mini connections with a speed drop to
  • 00:27:09
    USB to a small full speed connection was
  • 00:27:13
    still required in order to support the
  • 00:27:15
    extra pins for USB but still allow for
  • 00:27:18
    compatibility with USB to a flat micro
  • 00:27:21
    beef connection was created this
  • 00:27:24
    connector is essentially a USB micro-b
  • 00:27:27
    connector on the left with the extra
  • 00:27:30
    pins required for USB 3 on the right
  • 00:27:32
    this allows a USB two micro B connector
  • 00:27:36
    to be plugged into a USB 3 micro B
  • 00:27:39
    connector making it compatible with USB
  • 00:27:41
    2 and USB 3 this system makes it easy to
  • 00:27:45
    work out which is the master and the
  • 00:27:47
    slave side since the connector is
  • 00:27:49
    different and prevents it from being
  • 00:27:50
    plugged in the wrong way so how do we
  • 00:27:53
    allow a device to either act as a master
  • 00:27:55
    or a slave USB on-the-go
  • 00:27:59
    allows the device to either function as
  • 00:28:01
    a master or a slave to understand why
  • 00:28:04
    this would be important consider a
  • 00:28:06
    device like a mobile device you may want
  • 00:28:09
    to plug the mobile device into a
  • 00:28:11
    computer in order to access the storage
  • 00:28:13
    on the device
  • 00:28:14
    or you may want to plug in an external
  • 00:28:17
    keyboard into the device in order to
  • 00:28:20
    access the storage the mobile device
  • 00:28:22
    needs to work as a slave but in order to
  • 00:28:24
    access the keyboard the device needs to
  • 00:28:26
    act as a master to achieve this a
  • 00:28:29
    different type of plug needed to be
  • 00:28:31
    designed the first example is the mini a
  • 00:28:34
    B the mini a B allows either a micro a
  • 00:28:38
    or micro-b plug to be plugged into it
  • 00:28:41
    this makes sense since the device could
  • 00:28:44
    either be a master or slave you want to
  • 00:28:46
    be able to plug both in following this
  • 00:28:49
    you probably guessed it is the micro a B
  • 00:28:52
    plug once again this allows a micro a or
  • 00:28:56
    micro-b plug to be plugged in both these
  • 00:28:59
    plugs were designed for USB 2 for USB 3
  • 00:29:03
    a new type of plug the type C was
  • 00:29:05
    developed the type C plug is designed
  • 00:29:08
    for USB 3 however it is backward
  • 00:29:11
    compatible with USB 2 the type C
  • 00:29:14
    connection is a little different from
  • 00:29:16
    the other two connections in that it is
  • 00:29:18
    found on both ends
  • 00:29:20
    generally a B connectors were not found
  • 00:29:23
    on a computer but only devices like
  • 00:29:25
    mobile devices the type C connection
  • 00:29:28
    however can be found on computers
  • 00:29:30
    although does not commonplace yet USB
  • 00:29:33
    on-the-go was first introduced back in
  • 00:29:35
    2001 essentially it was added on to the
  • 00:29:39
    USB protocol to allow the device to
  • 00:29:41
    detect what the device on the other side
  • 00:29:43
    is essentially when both devices are
  • 00:29:47
    connected they will negotiate with each
  • 00:29:49
    other to determine which device is the
  • 00:29:51
    master now that we understand what
  • 00:29:54
    different types of USB there are on the
  • 00:29:56
    market let's consider what is the
  • 00:29:58
    maximum length of the cables we can use
  • 00:30:01
    for a low speed or USB 1 cable the
  • 00:30:04
    maximum length is 3 meters or 10 feet
  • 00:30:07
    for high speed or USB 2 the distance
  • 00:30:11
    increases to 5 meters or 16 feet for
  • 00:30:14
    SuperSpeed or USB 3 there is no official
  • 00:30:18
    length for the cables however it is
  • 00:30:20
    recommended to use cables that are 3
  • 00:30:22
    meters or 10 feet or shorter there are
  • 00:30:26
    factors of cables that will make cables
  • 00:30:28
    that are longer than these these cables
  • 00:30:31
    may or may not work correctly also the
  • 00:30:33
    quality of the cable can make a
  • 00:30:35
    difference in the length of the cable if
  • 00:30:36
    you need a cable that is longer than the
  • 00:30:39
    maximum length consider purchasing an
  • 00:30:41
    active cable I will cover these in
  • 00:30:44
    another video but essentially an active
  • 00:30:46
    cable uses power to retransmit or boost
  • 00:30:49
    the signal to allow the cable to be of a
  • 00:30:51
    longer length let's now have a look at
  • 00:30:54
    what happens when you put multiple USB
  • 00:30:56
    devices together which run at different
  • 00:30:58
    speeds for this example I have my USB 3
  • 00:31:02
    port I want to have my computer on the
  • 00:31:04
    other side of the room so I have used a
  • 00:31:07
    USB active extender an active extender
  • 00:31:10
    is a long USB cable that uses a chip in
  • 00:31:13
    the cable that retransmits the usb data
  • 00:31:16
    this uses some power from the computer
  • 00:31:18
    but allows the USB cable to be longer
  • 00:31:21
    since the USB extender only gives me one
  • 00:31:24
    port
  • 00:31:25
    I'm going to connect it to a USB 3
  • 00:31:27
    powered hub this will give me additional
  • 00:31:30
    ports that I can use connected to the
  • 00:31:33
    USB hub I will connect my KVM switch
  • 00:31:36
    this will allow me to share my keyboard
  • 00:31:38
    and mouse to different computers so you
  • 00:31:41
    can see I have multiple devices
  • 00:31:43
    connected together which run at
  • 00:31:45
    different speeds let's see how this is
  • 00:31:47
    handled to have a look at my setup I'm
  • 00:31:51
    going to use the software USB View USB
  • 00:31:54
    view is available in Windows SDK which
  • 00:31:56
    is a free download from Microsoft when
  • 00:31:59
    you install it you just need to select
  • 00:32:01
    the option debugging tool for Windows
  • 00:32:03
    this will install the executable for USB
  • 00:32:07
    view and you just need to run it
  • 00:32:08
    I will now run USB view you can see on
  • 00:32:14
    this computer it has two USB host
  • 00:32:16
    controllers some computers will have
  • 00:32:19
    more than one you can see under the
  • 00:32:21
    first USB controller there is a route up
  • 00:32:23
    there should only be the one in theory
  • 00:32:26
    you could have more than one but
  • 00:32:28
    generally manufacturers will only have
  • 00:32:30
    the one to have more than one would not
  • 00:32:33
    provide any advantage at this level
  • 00:32:35
    essentially the traffic at some stage
  • 00:32:37
    will still need to be combined together
  • 00:32:39
    into a
  • 00:32:40
    single upstream channel to be used by
  • 00:32:42
    the computer you can see the root hub is
  • 00:32:45
    connected to four USB ports
  • 00:32:47
    since this computer has two USB host
  • 00:32:50
    controllers one is 3.2 and the other is
  • 00:32:52
    3.1 this one is the faster one and thus
  • 00:32:55
    only has the four ports a faster device
  • 00:32:59
    needs more bandwidth and thus a computer
  • 00:33:01
    will generally only have a few of them
  • 00:33:03
    the four ports are connected to a USB
  • 00:33:05
    hub you will notice on the right side of
  • 00:33:08
    the screen the connection is USB 2 even
  • 00:33:12
    though this has appeared as a USB hub I
  • 00:33:14
    know this device is my active extender
  • 00:33:16
    sometimes devices you don't expect will
  • 00:33:19
    appear as hubs the device will appear
  • 00:33:22
    with 4 ports however since it is a cable
  • 00:33:25
    only one port will ever be used when I
  • 00:33:28
    expand the fourth port notice there are
  • 00:33:31
    four ports and another USB hub this does
  • 00:33:35
    not make sense as I'm using a seven port
  • 00:33:37
    USB hub what has occurred is that the
  • 00:33:41
    seven port USB hub appears as two hubs
  • 00:33:44
    one connected to the other
  • 00:33:47
    thus this accounts for the odd number of
  • 00:33:49
    ports seven as one port is lost to
  • 00:33:52
    connect the hubs together when I expand
  • 00:33:55
    the second hub
  • 00:33:56
    you will notice another hub on port 1
  • 00:33:58
    you will notice on this hub there are
  • 00:34:01
    two composite devices these devices are
  • 00:34:04
    my keyboard and mouse so this hub is my
  • 00:34:07
    KVM switch you will notice that when I
  • 00:34:10
    select one of the devices it is running
  • 00:34:11
    at USB 1.1 speed so essentially what has
  • 00:34:16
    happened is in order to connect my
  • 00:34:18
    keyboard and mouse the traffic needs to
  • 00:34:21
    go through five hubs including the root
  • 00:34:22
    of it did not take much effort to reach
  • 00:34:25
    this if you want to go beyond five tears
  • 00:34:28
    you can always try but it is not
  • 00:34:30
    guaranteed to work you also notice that
  • 00:34:34
    if I choose a different port on the
  • 00:34:35
    seven port USB hub I could have reduced
  • 00:34:39
    the number of hubs by one you'll also
  • 00:34:42
    notice that sometimes by changing a port
  • 00:34:44
    to a different USB port you may get the
  • 00:34:46
    device to work the USB hub is also
  • 00:34:50
    running at USB 2 rather than USB 3
  • 00:34:54
    it is possible from a hardware
  • 00:34:56
    perspective to have it run at usb3 even
  • 00:34:58
    though it is connected via a USB to
  • 00:35:00
    connection but in the real world this
  • 00:35:03
    does not occur the reason for this is
  • 00:35:06
    that the USB 2 connection will create a
  • 00:35:09
    bottleneck for the USB 3 devices
  • 00:35:11
    essentially slowing the devices down to
  • 00:35:14
    what it can handle which is USB to speed
  • 00:35:16
    so there is no point at running USB 3
  • 00:35:19
    speed by contrast in networking this
  • 00:35:23
    does not occur because devices on the
  • 00:35:25
    network can communicate with each other
  • 00:35:27
    in USB all devices communicate to and
  • 00:35:30
    from the computer and not to each other
  • 00:35:32
    so there is no need for this to occur to
  • 00:35:36
    put it in simple terms when you connect
  • 00:35:38
    a low-speed device all devices after
  • 00:35:41
    that device will need to reduce to the
  • 00:35:43
    speed of that device so if I want my
  • 00:35:46
    device in this case to run faster I will
  • 00:35:49
    need to replace my active USB 2 extender
  • 00:35:52
    with an active USB 3 extender I will now
  • 00:35:56
    have a look at the second USB host
  • 00:35:58
    controller notice that this controller
  • 00:36:01
    has 26 ports connected to it only the
  • 00:36:05
    fast USB connectors were on the first
  • 00:36:07
    host controller for example this
  • 00:36:09
    motherboard has a type-c connector on
  • 00:36:11
    this device I have a pair of headphones
  • 00:36:14
    connected which you can see has appeared
  • 00:36:16
    as a USB 1.1 device you will notice
  • 00:36:20
    further down there is another hub this
  • 00:36:23
    hub is connected at USB 3 speed this is
  • 00:36:26
    an interesting one these ports are the
  • 00:36:29
    USB ports on the front of my computer so
  • 00:36:31
    in my previous example if I connected my
  • 00:36:34
    USB extender to this port this would
  • 00:36:37
    have added to the number of tears by 1
  • 00:36:40
    something else to consider when
  • 00:36:42
    connecting USB devices you never quite
  • 00:36:45
    know how they are connected in the
  • 00:36:47
    computer sometimes a physical connection
  • 00:36:49
    to the computer will be connected not
  • 00:36:51
    directly to the root hub but to a hub
  • 00:36:53
    that is connected to the root hub you
  • 00:36:56
    will notice that there is another hub
  • 00:36:58
    with a mass storage device connected on
  • 00:37:00
    this computer I have a card reader
  • 00:37:03
    attached this card reader has a memory
  • 00:37:05
    card in the reader which has been data
  • 00:37:08
    as a mass storage device you will notice
  • 00:37:11
    that this device has also appeared as a
  • 00:37:13
    USB 3 device since there are no USB
  • 00:37:16
    connections between it and the computer
  • 00:37:18
    it can run at full speed there is one
  • 00:37:22
    more property of USB 3 that I want to
  • 00:37:24
    look at to see this I will disconnect my
  • 00:37:27
    USB 3 hub and plug it into this USB host
  • 00:37:31
    controller you will notice the USB 3 hub
  • 00:37:35
    has appeared connected to port 3 however
  • 00:37:38
    notice that it is working at USB 2 speed
  • 00:37:41
    that should not be the case since it is
  • 00:37:44
    connected directly to the computer you
  • 00:37:47
    will notice that there's another USB hub
  • 00:37:49
    connected to port 19 which is at USB 3
  • 00:37:52
    speed what happens with USB 3 devices is
  • 00:37:56
    that they have USB 2 and USB 3 Hardware
  • 00:38:00
    in them they appear as both USB 2 and
  • 00:38:03
    USB 3 devices essentially the hub is
  • 00:38:07
    connected to the computer via a USB 2
  • 00:38:09
    and a USB 3 connection running over the
  • 00:38:12
    same cable USB 2 devices will be
  • 00:38:16
    connected to the USB 2 hub and USB 3
  • 00:38:19
    devices will be connected to the USB 3
  • 00:38:21
    hub when I connected it using the USB 2
  • 00:38:25
    active extender essentially the USB 3
  • 00:38:28
    hub did not install because the
  • 00:38:30
    connection did not support it this is
  • 00:38:32
    how USB 3 supports USB 2 and USB 1.1
  • 00:38:36
    devices essentially USB 3 Hardware
  • 00:38:40
    supports both in the device and it is up
  • 00:38:43
    to the computer to connect to which one
  • 00:38:45
    it wants to use in the case of USB hubs
  • 00:38:48
    it will connect to both I hope you've
  • 00:38:52
    enjoyed this video from I T free
  • 00:38:54
    training on USB hopefully we helped you
  • 00:38:57
    understand it better until the next
  • 00:39:00
    video from us I would like to thank you
  • 00:39:01
    for watching
Tags
  • USB
  • connectivitat
  • tecnologia
  • dispositius
  • hubs USB
  • versions USB
  • potència
  • amplada de banda
  • compatibilitat
  • història USB