Freescale Semiconductor TWR-MCF52259-Ethenet, User Manual, Page: 129 / 166

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Introduction to USB
USB On-the-Go:
Negotiation process
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1. OTG-A (host) enables OTG-B (device) to become host by sending
SetFeature (b_hnp_enable) command to OTG-B (device).
2. OTG-A (host) suspends bus signaling so that OTG-B (device) can
now become host.
3. OTG-B (device) detects Suspend condition and turns off pull-up
resistor.
4. Because HNP is enabled, OTG-A (host) interprets this
“disconnect” as a request by the OTG-B (device) to become host.
5. OTG-A (host) turns on its pull-up resistor and becomes
peripheral/device.
HNP (Host Negotiation Protocol):
Continued on the next slide