Freescale Semiconductor TWR-MCF52259-Ethenet - Manual (Page 126)

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Introduction to USB USB On-the-Go:
How does it work?
To implement OTG, two new protocols were added in the USB 2.0
addendum. These new protocols allow USB OTG host wake-up
and role reversal respectively. They are:
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SRP = Session Negotiation Protocol
HNP = Host Negotiation Protocol
SRP introduces these new/expanded states:
OTG-A device: a_idle, a_wait_vfall, b_idle
OTG-B device : b_srp_init
HNP introduces these new/expanded new states:
OTG-A device: a_peripheral, a_suspend, a_idle
OTG-B device: b_idle, b_host, b_wait_acon, a_idle