D+D-

high speed ,usb device had one 1.5koR on D+
low speed ,usb device had one 1.5oR On D-
so if plug device to Host
if is hight speed device ,D+ mus to High
if is low speed device ,D- must to low
but as book said :
on usb host D+ D- ,the pull R must 15Ko ,

if you usb device had no 1.5Ko R on D+orD-,I thank the D+ D- must Low alway.