Figure 408. A-Device Hnp - STMicroelectronics STM32F405 Reference Manual

RM0090
6. The OTG_FS controller performs V
The host starts a new session by turning on V
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.
OTG core
DP
DM
DPPULLDOWN
DMPULLDOWN
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

Figure 408. A-device HNP

1
Host
Suspend 2 4
3
DocID018909 Rev 11
USB on-the-go full-speed (OTG_FS)
pulsing.
BUS
, indicating SRP success. The
BUS
Device
6
5
Reset Traffic
Traffic
Host
8
Connect
7
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