I strictly followed "Figure 19 Simple USB Type A Connection Example" of NVIDIA Jetson AGX Xav ier OEM Product Design Guide when designing our custom carrier board for Xavier SOM. And i have already noticed that GPIO22 (USB_VBUS_EN0) is active low signal:
HINT: according to the doc “P2822_B03_OrCAD_schematics”, where pin4 of part U2, i.e., APL3511DBI-TRG,
is an active low enable
however, in our custom carrier board, neither USB1_DP/USB1_DN nor UPHY6 does respond to USB device (including keyboard, mouse, USB mass storage device, etc.)
when connect to the keyboard, a voltage about 3.0V is measured on USB1_DN (this indicates the connected USB device is a low speed USB peripheral, since on Xavier, there must be a 15kohm pull-down resistor on USB1_DN, and USB keyboard will usually have a 1.5kohm pull-up resitor on USB1_DN,
3.3 * 15 / (15+1.5) = 3.0V, hence 3.0V notifies a low speed USB peripheral - keyboard, is connected to USB1_DP/USB1_DN port of Xavier, but Xavier appears to detect nothing at all)
any one help me with this issue ~ ?