ST STM32F413 Reference Manual page 1144

USB on-the-go full-speed (OTG_FS)
33.15.11 OTG non-periodic transmit FIFO/queue status register
(OTG_HNPTXSTS)
Address offset: 0x02C
Note: Reset value: 0x0008 0200 In Device mode, this register is not valid.
This read-only register contains the free space information for the non-periodic Tx FIFO and
the non-periodic transmit request queue.
31 30 29
Res.
r r
15 14 13
r r r
Bit 31 Reserved, must be kept at reset value.
Bits 30:24 NPTXQTOP: Top of the non-periodic transmit request queue
Bits 23:16 NPTQXSAV: Non-periodic transmit request queue space available
Bits 15:0 NPTXFSAV: Non-periodic Tx FIFO space available
1144/1284
28 27 26 25
NPTXQTOP
r r r r
12 11 10 9
r r r r
Entry in the non-periodic Tx request queue that is currently being processed by the MAC.
Bits 30:27: Channel/endpoint number
Bits 26:25:
00: IN/OUT token
01: Zero-length transmit packet (device IN/host OUT)
11: Channel halt command
Bit 24: Terminate (last entry for selected channel/endpoint)
Indicates the amount of free space available in the non-periodic transmit request queue.
This queue holds both IN and OUT requests.
0: Non-periodic transmit request queue is full
1: 1 location available
2: locations available
n: n locations available (0 ≤ n ≤ 8)
Others: Reserved
Indicates the amount of free space available in the non-periodic Tx FIFO.
Values are in terms of 32-bit words.
0: Non-periodic Tx FIFO is full
1: 1 word available
2: 2 words available
n: n words available (where 0 ≤ n ≤ 512)
Others: Reserved
24 23 22
r r r
8 7 6
NPTXFSAV
r r r
DocID029473 Rev 3
21 20 19 18
NPTQXSAV
r r r r
5 4 3 2
r r r r
RM0430
17 16
r r
1 0
r r