i am working on phillips host controller isp1161 but i am terribly facing problems..
i am using 89c55 as and 95288 cpld to generate addresing .
i am able to access all registers of isp1161
but i am not getting how should i generate usb packets so that i can request device descriptors and other descriptors from peripheral pen drive
whts the meanig of usb packtes?? how should i sum them up with PTD data structure of isp 1161?
can anyone give me just one example of how should i read device descriptor from pen drive????

the following things i have tried.....
i have written PTD for control transfer i.e setup transaction.
(8bytes PTD).
then i have written 6 bytes of setup token.
then i have wrtitten device descripotr reqeust(8 bytes)

now i am confused about the ack i.e status. how peripheral give ack? and how should i detect that it has succesfulyy acknoledge the requets?

just tell me wht sequence of operations are required for isp1161 to get the device descriptor from peripheral device.

i am using assembly languafe programig for 89c55wd and VHDL language for CPLD programming