Jetson nano module / USB2-USB3 ports confusion on speed

Robotics & Edge Computing Jetson & Embedded Systems Jetson Nano
1

Hi community,

In the data sheet of jetson nano module we can read (page 22/41):

“USB 2.0 Ports
Each USB 2.0 port operates in USB 2.0 High Speed mode when connecting directly to a USB 2.0 peripheral and operates in USB 1.1 Full and Low Speed modes when connecting directly to a USB 1.1 peripheral. All USB 2.0 ports operating in High Speed mode share one High Speed Bus Instance, which means 480 Mb/s theoretical bandwidth is distributed across these ports. All USB 2.0 ports operating in Full or Low Speed modes share one Full/Low Speed Bus Instance, which means 12 Mb/s theoretical bandwidth is distributed across these ports.”

1- I understand there is a shared 480 Mb/s bandwidth because of a single USB controler.
So if I use the three USB2.0 ports I will get a 160 Mb/s max theoretical bandwidth per port ?

2- Is it the same with USB3.0 ports (shared BW) ?

3- I have to connect 4 devices with USB2.0 ports on JNN module.
If I want the max USB2 speed (480 Mb/s) on each device port, I must use the USB3.0 port with a HUB ?

Regards,
Bernard FROMENT
Blue Frog Robotics
Electronics engineer

2

Hi, 1) Yes if all USB2.0 ports work simultaneously; 2) Only one USB3.0 port on nano; 3) It seems so.

3

Hi,

According to point3 : 4 USB2.0, each at full speed.

I’m not sure that this solution is the correct solution because after have a look to devKit carrier board schematics, I find a USB3 hub (4 channels).
This hub component is connected to USB3 signals but also to USB2 signals (USB1 port), so I can guess when the
hub detects USB2 devices it acts as a USB2 hub sharing the USB1 port (also sharing BW).

Got some information about that ?

Regards,
Bernard FROMENT
Blue Frog Robotics
Electronics engineer

4

You can use other hub which can bridge one USB3.0 to four USB2.0 ports.

5

Hi,

So IC exists ? Give me some ref if you have.
After have a look to this pb, it seems that if you connect a HUB on an UBS3 host port and 4 US2 devices:
The devices will shared the max USB2 max speed (480 Mb/s) but NOT the max USB3 speed.
I fact the hub acts as an USB2 hub.

Can you confirm this point ?

Regards,
Bernard FROMENT
Blue Frog Robotics
Electronics engineer

6

I have no such info of the IC/hub. Just a suggestion of searching bridge device of 1xUSB3 to 4xUSB2 ports.

The bandwidth of USB3.0 on nano is sufficient to support 4 USB2.0 ports at max speed, the problem is you need to find a appropriate bridge IC/hub for this.