Information

42.7.1 OTG Dual Role A Device Operation
A device is considered the A device because of the type of cable attached. If the USB
Type A connector or the USB Type Mini A connector is plugged into the device, he is
considered the A device.
A dual role A device operates as the following flow diagram and state description table
illustrates.
A_IDLE
A_WAIT_VFALL A_WAIT_VRISE
A_PERIPHERAL
A_SUSPEND
B_IDLE
A_WAIT_BCON
A_HOST
Figure 42-91. Dual Role A Device Flow Diagram
Table 42-94. State Descriptions for the Dual Role A Device Flow
State Action Response
A_IDLE If ID Interrupt.
The cable has been un-plugged or a Type B cable has been
attached. The device now acts as a Type B device.
Go to B_IDLE
If the A application wants to use the bus or if the B device is doing
an SRP as indicated by an A_SESS_VLD Interrupt or Attach or Port
Status Change Interrupt check data line for 5 –10 msec pulsing.
Go to A_WAIT_VRISE
Turn on DRV_VBUS
A_WAIT_VRISE If ID Interrupt or if A_VBUS_VLD is false after 100 msec
The cable has been changed or the A device cannot support the
current required from the B device.
Go to A_WAIT_VFALL
Turn off DRV_VBUS
If A_VBUS_VLD interrupt Go to A_WAIT_BCON
Table continues on the next page...
Chapter 42 Universal Serial Bus OTG Controller (USBOTG)
K20 Sub-Family Reference Manual, Rev. 6, Nov 2011
Freescale Semiconductor, Inc. 1085