USB on-the-go full-speed/high-speed (OTG_FS/OTG_HS) RM0390
1258/1328 RM0390 Rev 4
Figure 427. TRDT max timing case
31.16.8 OTG programming model
The OTG_FS/OTG_HS controller is an OTG device supporting HNP and SRP. When the
core is connected to an “A” plug, it is referred to as an A-device. When the core is connected
to a “B” plug it is referred to as a B-device. In host mode, the OTG_FS/OTG_HS controller
turns off V
BUS
to conserve power. SRP is a method by which the B-device signals the A-
device to turn on V
BUS
power. A device must perform both data-line pulsing and V
BUS
pulsing, but a host can detect either data-line pulsing or V
BUS
pulsing for SRP. HNP is a
method by which the B-device negotiates and switches to host role. In Negotiated mode
after HNP, the B-device suspends the bus and reverts to the device role.
A-device session request protocol
The application must set the SRP-capable bit in the core USB configuration register. This
enables the OTG_FS/OTG_HS controller to detect SRP as an A-device.
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