Time sensitivity: According to the V-USB documentation (the comments in usbdrv.h), the USB interrupt handler can take up to 100us (though this includes waiting for the host, so typical times may be shorter; for comparison, one X or Y step = approx 2000us), and must not be disabled for longer than 2us (25-40 clock cycles). However if this is not possible while printing, V-USB does allow the devicby rebecca.palmer - Next Wave Electronics Working Group