The USB rate has changed dramatically since it emerged in the late 90s, and with each new generation it has improved its capacity when it comes to data transfer, and we can’t forget that it was originally proposed as a plug-in and output connector. that didn’t require a lot of bandwidth like printers, mice, keyboards, etc.
With its 2.0 version, its bandwidth has increased from 12 Mbits / s to 480 Mbits / s, so it has been able to reach the IEEE-1394 port port, better known as Firewire. The result of this was the disappearance of the said port, and finally with the advent of USB 3.x it reached speeds of 5, 10 and even 20 Gbits / s, setting the bandwidth of external drives with the same speed and internal interface via SATA and beyond.
But the kind of connection until recently was not threatened by its presence via USB until recently when there were video output such as DisplayPort and HDMI, which could disappear day by day on our PCs. as in many other ways. Today we will talk about the case, USB-C Alt DP 2.0.
Description of USB-C Alt DP 2.0
USB-C Alt DP 2.0 cable is a Type-C USB cable that performs three functions:
- Send and receive data via USB 3.2 channels.
- Device power supply from USB cable.
- Send video data in the DisplayPort 2.0 protocol.
Given that USB-C Alt DP is a USB-C variant, we first need to understand how this interface works by looking at the pins for this type of connection and what each function is assigned to:
| Phina | Name | Work |
|---|---|---|
| A1 | GND | power supply |
| A2 | TX1 + | Alternative or USB 3.2 |
| A3 | TX1- | Alternative or USB 3.x |
| A4 | VBUS | power supply |
| A5 | CC or VCONN | |
| A6 | UD + | USB 2.0 display |
| A7 | D- | USB 2.0 display |
| A8 | SBU1 | One way is |
| A9 | VBUS | power supply |
| A10 | RX2 + | Alternative or USB 3.x |
| A11 | RX2- | Alternative or USB 3.x |
| A12 | GND | power supply |
| B1 | GND | power supply |
| B2 | TX2 + | Alternative or USB 3.x |
| B3 | TX2- | Alternative or USB 3.x |
| B4 | VBUS | power supply |
| B5 | CC or VCONN | |
| B6 | UD + | USB 2.0 display |
| B7 | D- | USB 2.0 display |
| B8 | SBU2 | One way is |
| B9 | VBUS | power supply |
| B10 | RX1 + | Alternative or USB 3.x |
| B11 | RX1- | Alternative or USB 3.x |
| B12 | GND | power supply |
To transfer data at high speed, USB-C uses 4 different methods namely: TX1 + – → RX1 +, TX1- → RX1-, TX2 + → RX2 + Y TX2– → RX2-.
Alternatively, in a different mode we can change these high-speed data channels as one of the 4 channels of the DisplayPort protocol video transmission standard and as a result we transmit video that releases those data channels and that the D + and D- (USB 2.0) pins are responsible for transmitting data .
Because each USB 3.2 channel has a bandwidth of 20 Gbps and each DisplayPort 2.0 standard channel has the same bandwidth, it is possible to transfer video with DP 2.0 in all its glory, and this means being able to reach 8K frames at 60 frames per second. with HDR-10, more than enough to cover all the requirements, as this equates to a limit range of up to 4K at 240 FPS.
On the other hand, as data can continue to be transmitted via D- and D + pins and power pins remain unchanged, it is possible to look at situations where the screen can be connected to a PC and does not require external power beyond what the cable itself provides, so it may be in the future. your graphics card with a USB-C Alt DP port that will handle the screen feeding you are using.
An example like this is the Oculus Link cable to connect the Oculus Quest 1 and 2 to the PC, and is that after all a real virtual headset is not just a mirror attached to the face. However, this is not the end of the app, as for example we may have a tablet with this type of interface that can be turned into an additional screen for use in our apps.
In general, the good thing is that USB-C Alt DP in the future allows us to reduce the number of cables in our table, completely eliminating the need for power cables for our screens.
If it’s the future, how come NVIDIA removed it from the RTX 3000?
What NVIDIA has removed is VitualLink which, although different from USB Alt DP for real units, has been rejected by all unit manufacturers of this type and therefore is not something that has a great future, more than a few months ago USB Alt DP 2.0, which we talked about in this post, emerged as a VESA standard. This means that NVIDIA did not have time to include it in its GeForce Ampere graphics cards but all indications are that the AMD RX 6000 will have a port of this type if the rumors are correct.
Mixed mode USB C Alt DP interface
We can only use 2 USB ports as 2 DisplayPort lines instead of 4.
This cuts DisplayPort’s available bandwidth in half, but at the same time allows 2 channels to be used to send and receive instant data, making the monitor a USB port to talk about. Do you want to connect to hard disk drives that you can directly access by providing expertise or games? This is one of the possibilities.
Will we see DisplayPort and / or HDMI being replaced by USB Alt DP 2.0 or will it all end with a technical anecdote? Only time will tell.
