USB reset handler
Clear endpoint
control transfer flags.
Application-
specific actions
to clear app
RX and TX
buffers
End of USB reset
handler
Application-
specific actions
to mark all
endpoints
unhalted
Application-
specific actions
to mark device
as not in
suspend mode
Application-
specific actions
to clear app
config, alt.
I/F .
Application-
specific actions
to mark device
as not remote
wake-enabled
Application-
specific actions
to clear local
copy of frame
number
USB_RESET
= 1?
Yes
Inform application
that the USB
reset has completed
and that device is in
default state.
No
Set IRQ_SRC.DS_CHG
to clear the interrupt.
DEVSTAT.
transaction and
= 1
USB Device Controller
1631
SPNU503C – March 2018
Copyright © 2018, Texas Instruments Incorporated
Universal Serial Bus (USB)
Figure 29-74. USB Device Reset Handler Flowchart
29.3.21 Suspend/Resume Interrupt Handler
When a USB device suspend/resume general USB interrupt occurs, the USB module has either entered
or left suspend mode. The CPU code must determine which and react appropriately (see
The suspend sense hardware is implemented to trigger only after 5 ms of bus idle. This forces compliance
with the
USB Specification Version 1.1
T
WTRSM
timing parameter (3 ms of IDLE to identify suspend, 2 ms
before the remote device can signal resume).
If the CPU wants to wake the device from suspend mode and remote wake-up enable is set
(DEVSTAT.R_WK_OK = 1), it must first turn its clock on (if stopped), and then set SYSCON2.RMT_WKP.
The device then drives resume.