RM0090: Reference manual - STMicroelectronics

USB on-the-go high-speed (OTG_HS) RM0090
OTG_HS Host frame interval register (OTG_HS_HFIR)
Address offset: 0x404
Reset value: 0x0000 EA60
This register stores the frame interval information for the current speed to which the
OTG_HS controller has enumerated.
31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
Reserved
Bits 31:16 Reserved, must be kept at reset value.
OTG_HS host frame number/frame time remaining register (OTG_HS_HFNUM)
Address offset: 0x408
Reset value: 0x0000 3FFF
This register indicates the current frame number. It also indicates the time remaining (in
terms of the number of PHY clocks) in the current frame.
1205/1416 Doc ID 018909 Rev 3
FRIVL
rw rw rw rw rw rw rw rw rw rw rw rw rw rw rw rw
Bits 15:0 FRIVL: Frame interval
The value that the application programs to this field specifies the interval between two
consecutive SOFs (FS), micro-SOFs (HS) or Keep-Alive tokens (LS). This field contains the
number of PHY clocks that constitute the required frame interval. The application can write a
value to this register only after the Port enable bit of the host port control and status register
(PENA bit in OTG_HS_HPRT) has been set. If no value is programmed, the core calculates
the value based on the PHY clock specified in the FS/LS PHY Clock Select field of the Host
configuration register (FSLSPCS in OTG_HS_HCFG):
frame duration × PHY clock frequency
Note: The FRIVL bit can be modified whenever the application needs to change the Frame
interval time.
31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
FTREM FRNUM
r r r r r r r r r r r r r r r r r r r r r r r r r r r r r r r r
Bits 31:16 FTREM: Frame time remaining
Indicates the amount of time remaining in the current frame, in terms of PHY clocks. This
field decrements on each PHY clock. When it reaches zero, this field is reloaded with the
value in the Frame interval register and a new SOF is transmitted on the USB.
Bits 15:0 FRNUM: Frame number
This field increments when a new SOF is transmitted on the USB, and is cleared to 0 when
it reaches 0x3FFF.