GD32VF103 User Manual
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21.3.
Block diagram
Figure 21-1. USBFS block diagram
USB Clock Domain
DP
DM
ID
VBUS
USB
interrupts
Register
OTG
Control
Host Port
Control
Device bus
control
SIE
USB FS
PHY
Data
FIFO
AHB Slave
UTMI
Mux
Transcation
Scheduler
USB Clock
48MHz
21.4.
Signal description
Table 21-1. USBFS signal description
I/O port
Type
Description
VBUS
Input
Bus power port
DM
Input/Output
Differential D-
DP
Input/Output
Differential D+
ID
Input
USB identification: Mini
connector identification port
21.5.
Function overview
21.5.1.
USBFS clocks and working modes
USBFS can operate as a host, a device or a DRD (Dual-role-Device), it contains an internal
full-speed PHY.The maximum speed supported by USBFS is full-speed.
The internal PHY supports Full-Speed and Low-Speed in host mode, supports Full-speed in
device mode, and supports OTG mode with HNP and SRP. The USB clock used by the
USBFS should be 48MHz. The 48MHz USB clock is generated from internal clocks in system,
and its source and divider factors are configurable in RCU.
The pull-up and pull-down resistors have already been integrated into the internal PHY and
they could be controlled by USBFS automatically according to the current mode (host, device