USB_MAX_FS_ISOC_FRAMES_PER_XFER
#if (EHCI_VIRTUAL_FRAMELIST_COUNT < USB_MAX_FS_ISOC_FRAMES_PER_XFER)
#if (OHCI_VIRTUAL_FRAMELIST_COUNT < USB_MAX_FS_ISOC_FRAMES_PER_XFER)
#if (UHCI_VFRAMELIST_COUNT < USB_MAX_FS_ISOC_FRAMES_PER_XFER)
frame_limit = USB_MAX_FS_ISOC_FRAMES_PER_XFER;