ST STM32F40 Series Reference Manual page 1221

USB on-the-go high-speed (OTG_HS)
Bits 12:11 PFIVL: Periodic (micro)frame interval
Bits 10:4 DAD: Device address
Bit 3 Reserved, must be kept at reset value.
Bit 2 NZLSOHSK: Nonzero-length status OUT handshake
Bits 1:0 DSPD: Device speed
1221/1422
Indicates the time within a (micro) frame at which the application must be notified using the
end of periodic (micro) frame interrupt. This can be used to determine if all the isochronous
traffic for that frame is complete.
00: 80% of the frame interval
01: 85% of the frame interval
10: 90% of the frame interval
11: 95% of the frame interval
The application must program this field after every SetAddress control command.
The application can use this field to select the handshake the core sends on receiving a
nonzero-length data packet during the OUT transaction of a control transfer's Status stage.
1: Send a STALL handshake on a nonzero-length status OUT transaction and do not send
the received OUT packet to the application.
0: Send the received OUT packet to the application (zero-length or nonzero-length) and
send a handshake based on the NAK and STALL bits for the endpoint in the device endpoint
control register.
Indicates the speed at which the application requires the core to enumerate, or the
maximum speed the application can support. However, the actual bus speed is determined
only after the chirp sequence is completed, and is based on the speed of the USB host to
which the core is connected.
00: High speed
01: Reserved
10: Reserved
11: Full speed (USB 1.1 transceiver clock is 48 MHz)
Doc ID 018909 Rev 4
RM0090