Device Frame Number Register
| Bit | 31 | 30 | 29 | 28 | 27 | 26 | 25 | 24 | |
| Access | |||||||||
| Reset |
| Bit | 23 | 22 | 21 | 20 | 19 | 18 | 17 | 16 | |
| Access | |||||||||
| Reset |
| Bit | 15 | 14 | 13 | 12 | 11 | 10 | 9 | 8 | |
| FNCERR | FNUM[10:5] | ||||||||
| Access | |||||||||
| Reset | 0 | 0 | 0 | 0 | 0 | 0 | 0 | ||
| Bit | 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 | |
| FNUM[4:0] | MFNUM[2:0] | ||||||||
| Access | |||||||||
| Reset | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | |
Micro Frame Number
This field contains the 3-bit micro frame number information. It is provided in the last received MSOF packet.
This field is cleared at the beginning of each start of frame (SOF interrupt) or upon receiving a USB reset.
MFNUM is updated even if a corrupted MSOF is received.
Frame Number
This field contains the 11-bit frame number information. It is provided in the last received SOF packet.
This field is cleared upon receiving a USB reset.
FNUM is updated even if a corrupted SOF is received.
Frame Number CRC Error
| Value | Description |
|---|---|
| 0 | Cleared upon receiving a USB reset. |
| 1 | Set when a corrupted frame number (or microframe number) is received. This bit and the SOF (or MSOF) interrupt bit are updated at the same time. |