18f4550 USB and pulsin or pulsin alternative

Hello.

I have got DT's modified 'USBdemo' w/ instant interrupts working. I have some sensors I want to hook in which use pulsin. I understand USB needs to be serviced roughly once per MS. A shame. My measurements are between 5 and 15ms. I read other similar questions in the forums, but didnt see any resolutions beyond advice to try DT's instant interrupts. I am not savvy enough to know what to do with them.

With the instant interrupt enabled usb code, I am having trouble getting reliable behavior. Any suggestions? I can setup a CCP interrupt and write my own pulsin program?

This is for my robot. I have the option of using a second MCU and having both rs-232 and USB interfaces, but I was hoping to use just 1 mcu. Good learning experience I tell myself..

Thanks for any ideas on taking 2 to 20ms measurements in 1 or 2us resolution while also servicing USB.

R
http://www.1318cermak.com/robot.jpg