43.7.1 OTG dual role A device operation
A device is considered the A device because of the type of cable attached. If the USB
Type Standard-A or Micro-A plug is plugged into the device, it 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 43-8. Dual role A device flow diagram
Table 43-8. State descriptions for the dual role A device flow
State Action Response
A_IDLE If ID Interrupt.
The cable has been unplugged 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
A_WAIT_BCON After 200 ms without Attach or ID Interrupt. (This could wait forever
if desired.)
Go to A_WAIT_FALL
Turn off DRV_VBUS
A_VBUS_VLD Interrupt and B device attaches Go to A_HOST
Table continues on the next page...
On-The-Go operation
K22F Sub-Family Reference Manual, Rev. 4, 08/2016
1114 NXP Semiconductors
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