Hi guys, I have a question regarding transmission lines and splitting/branching traces of the D+/D- pair.
I have a concern related to a simple Micro USB connector that can work with both USB 1.0 and 2.0 ICs. I’m currently working on a test board that has three potential modules connecting to a single Micro USB connector. However, only one module will be connected at a time.
My first question is, can I split the D+/D- lines using a Y-shaped connection to connect two or three modules? Will USB 2.0 still function properly in this configuration?
Alternatively, would it be better to daisy chain the modules?
Another idea I had was to create the Y-shaped connection using zero-ohm resistors, and then remove any unused ones to optimize the length of the stubs. Would this be a better solution?
Or perhaps a star-like connection, where a central node connects all the modules close to the Micro USB connector?
I would appreciate it if you could suggest any other alternatives or provide insight into the best approach. Thank you.
There is such a thing as USB 2.0 “high speed”. I speculate that if you are just connecting something slow such as a mouse, that transmission line impedance and reflections might not be much of a concern. But if you were connecting to a laser printer, you might find (if your luck is not too bad) that speed suffers (or if your luck is worse) that it does not work at all. (??)
if it’s just a “test board”, then why not just put down 3 usb connectors? if you try and connect three chips to one usb connector you’ll have some stubs even if you use 0-ohm jumpers. if you have issues with any of the chips you won’t know if it’s because of the stubs or something else.
