Functional Description
Table 16-8. Isochronous OUT Error Handling: Peripheral Mode (continued)
No. Packet(s) Expected
Data Packet(s) Received
Response
DATA2
INCOMPRX Set
MDATA
INCOMPRX Set
MDATA DATA0
PID Error set
MDATA DATA1
OK
MDATA DATA2
INCOMPRX Set
MDATA MDATA
INCOMPRX Set
MDATA MDATA DATA0
PID Error set
MDATA MDATA DATA1
PID Error set
MDATA MDATA DATA2
OK
MDATA MDATA MDATA
PID Error set
16.3.8.2 USB Controller Host Mode Operation
The USB controller assumes the role of a host when the USBx_ID pin state is grounded or USB Mode
Register[iddig=bit8] is cleared to 0 (provided that iddig_mux, which is bit7 of USBnMODE is also set to 1)
by the user application prior to the controller goes into session. When the USB controller go into session,
application/firmware sets the DEVCTL[SESSION] bit to 1, it will assume the role of a host.
•
Entry into Suspend mode. When operating as a host, the USB controller can be prompted to go into
Suspend mode by setting the SUSPENDM bit in the POWER register. When this bit is set, the
controller will complete the current transaction then stop the transaction scheduler and frame counter.
No further transactions will be started and no SOF packets will be generated.
If the ENSUSPM bit (bit 0 of POWER register) is set, the UTMI+ PHY will go into low-power mode
when the controller goes into suspend mode.
•
Sending Resume Signaling. When the application requires the controller to leave suspend mode, it
needs to clear the SUSPENDM bit in the POWER register, set the RESUME bit and leave it set for
20ms. While the RESUME bit is high, the controller will generate Resume signaling on the bus. After
20 ms, the CPU should clear the RESUME bit, at which point the frame counter and transaction
scheduler will be started.
•
Responding to Remote Wake-up. If Resume signaling is detected from the target while the controller is
in suspend mode, the UTMI+ PHY will be brought out of low-power mode and UTMI clock is restarted.
The controller will then exit suspend mode and automatically set the RESUME bit in the POWER
register (bit 2) to ‘1’ to take over generating the Resume signaling from the target. If the resume
interrupt is enabled, an interrupt will be generated.
•
Reset Signaling. If the RESET bit in the POWER register (bit 3) is set while the controller is in Host
mode, it will generate Reset signaling on the bus. If the HSENAB bit in the POWER register (bit 5) was
set, it will also try to negotiate for high-speed operation. The software should keep the RESET bit set
for at least 20 ms to ensure correct resetting of the target device. After the software has cleared the bit,
the controller will start its frame counter and transaction scheduler. Whether high-speed operation is
selected will be indicated by HSMODE bit of POWER register (bit 4).
1718
Universal Serial Bus (USB)
SPRUH73H – October 2011 – Revised April 2013
Copyright © 2011–2013, Texas Instruments Incorporated