B_IDLE
B_HOST B_SRP_INIT
B_WAIT_ACON
A_IDLE
B_PERIPHERAL
Figure 35-94. Dual role B device flow diagram
Table 35-97. State descriptions for the dual role B device flow
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
B_SRP_INIT If ID\ Interrupt or SRP Done (SRP must be done in less than 100
ms.)
Go to B_IDLE
B_PERIPHERAL If HNP enabled and the bus is suspended and B wants the bus, the
B device can become the host.
Go to B_WAIT_ACON
Turn off DP_HIGH
B_WAIT_ACON If A connects, an attach interrupt is received Go to B_HOST
Turn on Host Mode
If ID\ Interrupt or B_SESS_VLD/ Interrupt
If the cable changes or if VBUS goes away, the host doesn't support
us.
Go to B_IDLE
Go to B_IDLE
If 3.125 ms expires or if a Resume occurs Go to B_PERIPHERAL
B_HOST If ID\ Interrupt or B_SESS_VLD\ Interrupt
If the cable changes or if VBUS goes away, the host doesn't support
us.
Go to B_IDLE
If B application is done or A disconnects Go to B_PERIPHERAL
On-The-Go operation
KL25 Sub-Family Reference Manual, Rev. 3, September 2012
650 Freescale Semiconductor, Inc.
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