ST STM32F207 Series Reference Manual page 1010

USB on-the-go full-speed (OTG_FS)
Bits 31:16 Reserved, must be kept at reset value.
Bits 15:0 FRIVL: Frame interval
– Frame interval = 1 ms × (FRIVL - 1)
OTG_FS Host frame number/frame time remaining register (OTG_FS_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.
31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10
r r r r r r r
Bits 31:16 FTREM: Frame time remaining
Bits 15:0 FRNUM: Frame number
OTG_FS_Host periodic transmit FIFO/queue status register
(OTG_FS_HPTXSTS)
Address offset: 0x410
Reset value: 0x0008 0100
This read-only register contains the free space information for the periodic TxFIFO and the
periodic transmit request queue.
31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10
PTXQTOP
r r r r r r r
1010/1381
The value that the application programs to this field specifies the interval between two
consecutive SOFs (FS) 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_FS_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_FS_HCFG). Do not change the value of this field
after the initial configuration.
FTREM
r r r r r r
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.
This field increments when a new SOF is transmitted on the USB, and is cleared to 0 when
it reaches 0x3FFF.
PTXQSAV
r r r r r r
r r r r r r r
r r r r r r r
RM0033 Rev 9
9 8 7 6 5
FRNUM
r r r r r r r
9 8 7 6 5
PTXFSAVL
r r r r r r r
RM0033
4 3 2 1 0
r r r r r
4 3 2 1 0
r r r r r