Appendix A USB On-the-Go

USB On-the-Go:Negotiation process

SRP (Session Request Protocol) Negotiations

OTG-B (device) asks OTG-A (host) for a USB OTG session by signaling in one of two ways:

Pulsing an analog data line (D+ or D-), andTM

Pulsing VBUS through a relatively high impedance ( > 281 Ω)

Note: The B-device pulses data line first and then pulses VBUS

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Freescale Semiconductor TWR-MCF52259-Ethenet manual SRP Session Request Protocol Negotiations