USB Enumeration Logic

Can anyone pls clarify me how is the logic flow of the enumeration process? (such as when are the descriptors, packets coming one after another)

Thank you

enumeration is done by device class, ie how it will require/process data.

have a look here:

https://www.tech-pro.net/intro_usb.html

USB enumeration is partly dependent on the usbd driver and partly dependent on the functional driver. I've seen win98/win2k/winxp/wince enumerations and they all differ from each other. You should code your firmware to be able to handle all USB enumeration requests, and not try to enumerate them in a particular sequence.