DocID018909 Rev 11 1365/1731
RM0090 USB on-the-go full-speed (OTG_FS)
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6. The OTG_FS controller performs V
BUS
pulsing.
The host starts a new session by turning on V
BUS
, indicating SRP success. The
OTG_FS controller interrupts the application by setting the session request success
status change bit in the OTG interrupt status register. The application reads the session
request success bit in the OTG control and status register.
7. When the USB is powered, the OTG_FS controller connects, completing the SRP
process.
A-device host negotiation protocol
HNP switches the USB host role from the A-device to the B-device. The application must set
the HNP-capable bit in the Core USB configuration register to enable the OTG_FS
controller to perform HNP as an A-device.
Figure 408. A-device HNP
1. DPPULLDOWN = signal from core to PHY to enable/disable the pull-down on the DP line inside the PHY.
DMPULLDOWN = signal from core to PHY to enable/disable the pull-down on the DM line inside the PHY.
1. The OTG_FS controller sends the B-device a SetFeature b_hnp_enable descriptor to
enable HNP support. The B-device’s ACK response indicates that the B-device
supports HNP. The application must set host Set HNP Enable bit in the OTG Control
ai15683
OTG core
DP
DM
DPPULLDOWN
DMPULLDOWN
Host Device Host
1
Suspend 2
3
45
Reset
6
Traffic 7
8
Connect
Traffic
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