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Universal Serial Bus, OTG Capable Controller
MCF52211 ColdFire® Integrated Microcontroller Reference Manual, Rev. 2
15-38 Freescale Semiconductor
15.7.2 OTG Dual Role B Device Operation
A device is considered a B device if it connected to the bus with a USB Type B cable or a USB Type Mini
B cable.
A dual role B device operates as the following flow diagram and state description table illustrates.
Figure 15-34. Dual Role B Device Flow Diagram
A_SUSPEND
If ID Interrupt, or if 150 msec B disconnect timeout (This
timeout value could be longer) or if A_VBUS_VLD\ Interrupt
Go to A_WAIT_VFALL
Turn off DRV_VBUS
If HNP enabled, and B disconnects in 150 msec then B device
is becoming the host.
Go to A_PERIPHERAL
Turn off Host Mode
If A wants to start another session Go to A_HOST
A_PERIPHERAL If ID Interrupt or if A_VBUS_VLD interrupt Go to A_WAIT_VFALL
Turn off DRV_VBUS.
If 3 –200 msec of Bus Idle Go to A_WAIT_BCON
Turn on Host Mode
A_WAIT_VFALL If ID Interrupt or (A_SESS_VLD/ & b_conn/) Go to A_IDLE
Table 15-39. State Descriptions for Figure 15-34
State Action Response
B_IDLE If ID\ Interrupt.
A Type A cable has been plugged in and the device should now
respond as a Type A device.
Go to A_IDLE
If B_SESS_VLD Interrupt.
The A device has turned on VBUS and begins a session.
Go to B_PERIPHERAL
Turn on DP_HIGH
If B application wants the bus and Bus is Idle for 2 ms and the
B_SESS_END bit is set, the B device can perform an SRP.
Go to B_SRP_INIT
Pulse CHRG_VBUS Pulse
DP_HIGH 5-10 ms
Table 15-38. State Descriptions for Figure 15-33 (continued)
State Action Response
B_IDLE
B_HOST B_SRP_INIT
B_WAIT_ACON
A_IDLE
B_PERIPHERAL