Datasheet

32.8.2.4 Device Frame Number

Name: FNUM

Offset: 0x10

Reset: 0x0000

Property: Read only

Bit 15 14 13 12 11 10 9 8

FNCERR FNUM[10:5]

Access

R/W R/W R/W R/W R/W R/W R/W

Reset 0 0 0 0 0 0 0

Bit 7 6 5 4 3 2 1 0

FNUM[4:0] MFNUM[2:0]

Access

R/W R/W R/W R/W R/W R/W R/W R/W

Reset 0 0 0 0 0 0 0 0

Bit 15 – FNCERR Frame Number CRC Error

This bit is cleared upon receiving a USB reset.

This bit is set when a corrupted frame number (or micro-frame number) is received.

This bit and the SOF (or MSOF) interrupt bit are updated at the same time.

Bits 13:3 – FNUM[10:0] Frame Number

These bits are cleared upon receiving a USB reset.

These bits are updated with the frame number information as provided from the last SOF packet even if a

corrupted SOF is received.

Bits 2:0 – MFNUM[2:0] Micro Frame Number

These bits are cleared upon receiving a USB reset or at the beginning of each Start-of-Frame (SOF

interrupt).

These bits are updated with the micro-frame number information as provided from the last MSOF packet

even if a corrupted MSOF is received.

SAM D21 Family

USB – Universal Serial Bus

Datasheet Complete

DS40001882D-page 830