About USB2.0 plug-in and switch

Ejack1979

About USB2.0 plug-in and switch [Copy link]

Can I use a high-speed analog switch such as TS3USB31 to switch DM/DP?

According to the 3.0 protocol, the complete insertion/removal process needs to detect the VBus timing, and if only the data line is cut, it will definitely not meet the requirements. However, the early USB1.0/1.1 seems to only cut the data line.

So I'm curious, if the data cable between the host and the device is disconnected, how will the Windows system react? Will it eject the device with a normal ding-dong sound, or will it pop up a bubble to indicate that there is a problem with the device? If the data cable is reconnected, will it detect the insertion of the device with a normal ding-dong sound, or will it remain in the faulty state?

Oh, let me tell you the background: there is an awkward requirement, which requires that the photoelectric touch device (USB2.0 HID, actually it is probably a 1.0/1.1 device) be "unplugged" from the PC under certain conditions; and then "plugged" again under certain conditions.

cruelfox

Vbus can work without any connection. The device can be powered by itself without this power supply.

littleshrimp

Isn't it a device designed by yourself? Why not implement the plug-in and pull-out function through software?

Ejack1979

littleshrimp posted on 2020-12-16 19:56 Isn't it a device designed by yourself? Why not implement the plug-in and pull-out function through software?

It is not designed by myself, but I need an additional switch to control the touch function of the computer's external touch screen.

Party A’s thoughts are always cruel and cruel…

Ejack1979

cruelfox posted on 2020-12-16 17:51 Vbus can work without any connection. The device is powered by itself without this power supply.

No, no, no, I am not a USB device. I want to control the connection between the touch screen USB port and the PC...

Party A said that your device should have this LCD touch screen only display without touch under xxx circumstances, and then touch under xxx circumstances...

The PC is not mine, the LCD touch screen is not mine, but Party A thinks I should get involved in this mess...

littleshrimp

Ejack1979 posted on 2020-12-17 08:36 It is not designed by myself, but I need an additional switch to control the touch function of the touch screen of the computer. Party A's ideas are always cruel...

Find a USB device, disconnect the data cable, and put a double-pole single-throw switch in the middle to try

wsmysyn

I remember there is a two-choice bus switch, which should be possible.

Ejack1979

wsmysyn posted on 2020-12-17 15:03 I remember there is a two-choice bus switch, which should be possible,

Yes, I am planning to use a USB bus switch, but I doubt whether it can be realized by only switching the data line.

wsmysyn

Ejack1979 posted on 2020-12-17 15:16 Yes, I am planning to use a USB bus switch, but I doubt whether it can be realized by only switching on and off the data line.

There should be no problem. You can find a USB2.0 bus switch chip datasheet and look at typical applications. The termination resistors required by USB should be integrated in the chip. The host should be able to detect whether DP and DM are connected. Disconnecting the data line and then plugging it in will change the state of the host's USB data line. The host thinks that a device has come in and will follow the standard USB process.