Universal Serial Bus (USB)
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- Опубліковано 30 тра 2024
- In this video from ITFreeTraining I will look at the Universal Serial Bus or USB. USB standardized the connections to peripherals and has become very popular. Due to its popularity, it is essential for the IT technician to have a good understanding of how USB works.
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Universal Serial Bus (USB)
0:19 Universal Serial Bus or USB was released in 1996. It provides connectors and cables to connect peripherals and devices. USB was originally designed to replace the PS/2 plug which was used for the keyboard and mouse.
The PS/2 connector was limited to only being able to be used for keyboard and mouse. USB was designed to support any device that was manufactured to be compatible with USB. For example, USB could be used for USB sticks, connecting printers or even your mobile device.
USB was designed to be hot swappable. This means that you can connect and disconnect devices from your computer without rebooting the computer. USB is also auto configurable. In the old days of computing, interrupts, ports and other settings would need to be configured. However, with USB the resources the device requires are automatically allocated.
Nowadays, USB has become very popular and it would be hard to find a computer that does not have at least one USB port. USB is used to connect every device you could think of to your computer. Let’s have a look at how it works.
USB Host Controller
1:33 At the heart of USB is the USB host controller. The USB host controller provides an interface to communicate with the hardware. Each host controller has one root hub. Regardless of how many USB controllers you have, the operating system will communicate with the USB controller using a standard interface.
In this example, there is one chip in the computer that provides a USB host controller. Nowadays, the USB Host Controller will not be a separate chip but will most likely be found in the North Bridge. In some motherboards the newer faster USB 3 controller would be found in the North Bridge and the older slower USB 2 controller would be found in the South Bridge. I will look at the different versions of USB later in the video.
Regardless of how many USB controllers you have on your motherboard, their versions and if they are on one chip or more, they essentially work the same way.
Each USB Host controller can support a maximum of 127 devices. In the real world it is unlikely this maximum will be reached for a number of reasons which I will look at later in the video. To manage a large number of devices using the one USB host controller, each USB host controller has one or more root hubs.
In this example, you can see the USB host controller is connected to the root hub. The root hub is then connected to the physical USB ports. The USB host controller may support more physical ports than what are available on the motherboard. It is up to the manufacturer of the motherboard to determine how many physical ports they are going to support.
Now you may be thinking, if one controller can potentially support 127 devices, there are no motherboards on the market that have anywhere close to 127 USB connectors. There are motherboards that have 16 USB connectors, which should be enough. So, let’s have a look at why you would need to support so many.
USB Hub
3:42 USB has the ability for one port to be expanded to many ports. This is the same principal as a power strip. Shown here is a USB hub. This USB hub allows one USB connection to be split into four connections. USB hubs can be separate devices like this one or can be included in devices like computer monitors and keyboards.
The USB hub has an input port which is referred to as an upstream port. This will be connected directly to the computer or another USB hub. In the case of this USB hub, there are four downstream ports which devices or other USB hubs can be connected to. In this case, a USB thumb drive is connected to one of the ports. Another one of the ports is connected to a second hub.
In a previous video, we looked at what would happen if you connected multiple power strips together. Let’s have a look at the problem that may occur if you connect multiple USB hubs together.
Description too long for UA-cam. Please see the following link for the rest of the description. itfreetraining.com/ap/1c15
References
“The Official CompTIA A+ Core Study Guide (Exam 220-1001)” Chapter 3 Lesson 9322 - 10272
“CompTIA A+ Certification exam guide. Tenth edition” Pages 392 - 400
“USB” en.wikipedia.org/wiki/USB
“USB hub” en.wikipedia.org/wiki/USB_hub
“USB 3.0” en.wikipedia.org/wiki/USB_3.0
“Picture of white concrete” www.pexels.com/photo/backgrou...
Credits
Trainer: Austin Mason ITFreeTraining.com
Voice Talent: HP Lewis hplewis.com
Quality Assurance: Brett Batson www.pbb-proofreading.uk
This is such a confusing subject, but you have done a wonderful job breaking it down to make it much easier to understand. I now have a picture of the USB naming with the speed as the well as the horrible new naming chart on my phone. This has made it much easier to understand what I'm buying. Thank you!
Thanks. Hopefully when they start using USB4 they won't make it as confusing.
Welcome sir.. there is a magic in your voice 👍👍👍
Expecting more and more videos from you.. happy to follow ur channel
Thank you very much am from Ghana
I love your teaching
You are very welcome
Am so happy meeting you and follow your channel
Thanks, and thank for following the channel.
I wish you were my IT teacher in college.
Thanks very much.
I enjoyed viewing your video. Well done. Frankly it is the only professionally done video on this subject. Since you are very knowledgeable about USB subject, I would appreciate your help in solving my USB driver problem. I cannot update the Universal Serial Bus (USB) Controller in the Windows 7 Device manager. My motherboard is an i5 Intel and I have gone to the Intel site for a driver without success. I also have looked all over the internet for a driver for that Controller without success. My device cannot work without that, and I really don't know what to do. That is why I am asking for your help in locating a driver for that controller and would greatly appreciate any assistance. Looking forward to hear from you.
Awsome explaination not found elsewere
Thanks very much.
Are the plug colors of type A reliable indicators of the port speed?
In most cases, the plug colors of Type A USB connectors are not reliable indicators of the port speed. USB Type A connectors come in various colors, but these colors are primarily used for aesthetic or branding purposes and don't necessarily correspond to specific USB versions or speeds. Although most manufactures follow the de-facto standard. If you are not sure if it is USB 2 or USB 3, have a look in the connector and see how many pins it has.
I'm sort of confused about the master/slave connection types. If the USB is type A, is it always a master and if it's a USB type B, is it always a slave? If so why is that the case? Would USB type C also be considered a slave type because it's not type A?
Essentially USB has the ability to detect if it should be a slave or a master. The simplest example is a mobile device. If it is plugged into a computer it needs to be a slave since it is sharing it storage with the computer. If you plug a device like a keyboard into the mobile device, the mobile device needs to act as a master since the keyboard would be a slave device.
Thus, the type of plug you use does not determine if it is a slave or a master. What is connected on the other end does. However, by convention we use type A as the master connection and type B is the slave.
Problems can occur however if you use the wrong plugs because the original USB standard if both sides are powered (Both masters) the protocol did not account for this. Thus, USB 2 it is not recommended to plug a master in a master connection. Thus, you never use to see USB A to USB A connections, although they do exists for a few rare devices. If you accidently plugged a master connection to another it could case damage. For example, computers are masters thus if you plugged two computers together this could cause damage. Thus, having different connectors prevented this from happening.
With USB 3 the protocol changed so that you could plug two masters together and it would not damage anything. Thus, the type-c connection this is not a concern anymore and thus no need to have different types of plugs.
Good job :)
Thank you! Cheers!
Now make them more sturdy.
That is a problem, but I don't know what the answer is.
How do we know how many usb root hub does my pc have and to which usb? Is this even possible to know? Thanks
The simplest way is to use USBView.
There are instructions how to download and use it here:
learn.microsoft.com/en-us/windows-hardware/drivers/debugger/usbview
🙏🌹
Thanks for watching.
Comments on image so it difficult to watch
I think you mean captions, you can always switch these off or make the video full screen and it is easier to see.
@@itfreetraining ooo yes yes! just now i notice that CC option 🤣🤣🤣