Inline USB 2.0 switch for test automation – how to simulate clean disconnect/rec

[mastupristi]

Hi all,

I'm working on a small USB-controlled inline device that sits between a USB host (typically a PC with a USB-A or USB-C port) and a USB device (either USB Micro-B or USB-C). 
The goal is to simulate a USB cable disconnect/reconnect under software control — to trigger device re-enumeration, activate bootloaders, or perform power-cycle testing as part of automated QA.

The USB link is always USB 2.0, and devices may be either Full Speed or High Speed.


Use case

I work with different classes of devices:

• A USB 2.0 device with a Micro-B connector, drawing minimal current, no negotiation involved
• A USB 2.0 device with a USB-C connector that relies on current negotiation, e.g. it negotiate to draw 1.5 A
• etc...

I would like to be able to disconnect/reconnect the device to the host in a controlled way. Just like a switch that behave exactly like a passive cable during normal operation, but simulate a physical detach/reattach event when controlled by a microcontroller (e.g., via GPIO). 
In this scenario, the system should remain as transparent as possible and not interfere with expected power negotiation behavior, especially for USB-C devices.

“Active” components, such as hubs, could be used instead, but always with the ability to disconnect ports via software


Constraints

• USB 2.0 only (no USB 3.x or USB PD involved)
• Host is USB-A or USB-C
• Device side may be USB-C or Micro-B
• Some USB-C devices expect 1.5 A capability (maybe more in the future)
• Devices may run at High Speed (480 Mbps), so any switching must be signal-integrity friendly
• Simple, robust implementation preferred (ideally without requiring USB drivers or protocol stacks)

Conceptual block diagram

Here's the high-level idea:



The "switch block" might control VBUS, CC (for USB-C), and possibly D+/D− if needed.


Open questions

I'm evaluating a few possible approaches, and I’d love to hear feedback from others who’ve worked on similar USB tools:

• What USB lines need to be switched to properly simulate a clean detach from the device’s perspective?
  • Is switching only VBUS enough?
  • Do I need to disconnect CC (for USB-C)?
  • Should D+/D− be switched as well for High Speed?
• Is there a better approach using USB redrivers with enable/disable control?
• Would a USB 2.0 hub IC (e.g. USB2412) with per-port power control be a better, more spec-compliant choice?
• What kind of switches (analog/SPDT/SPST) are usable for CC or D+/D− in USB 2.0 High Speed?
• Any other chip suggestions or reference designs?

I'm not looking for one specific solution — I'm open to advice on architecture, part selection, and general experience. 
Has anyone here built something similar? Any thoughts are welcome.

Thanks in advance!