Rainbow-electronics AT89C5131 Manual de usuario descargar pdf (Pagina 144)

144

AT89C5131

4136A–USB–03/03

Table 96. UFNUMH Register

UFNUMH (S:BBh, read-only)

USB Frame Number High Register

Reset Value = 00h

Table 97. UFNUML Register

UFNUML (S:BAh, read-only)

USB Frame Number Low Register

Reset Value = 00h

76543210

- - CRCOK CRCERR - FNUM10 FNUM9 FNUM8

Bit

Number

Bit

Mnemonic Description

5 CRCOK

Frame Number CRC OK

This bit is set by hardware when a new Frame Number in Start of Frame Packet

is received without CRC error.

This bit is updated after every Start of Frame packet receipt.

Important note: the Start of Frame interrupt is generated just after the PID receipt.

4 CRCERR

Frame Number CRC Error

This bit is set by hardware when a corrupted Frame Number in Start of Frame

packet is received.

This bit is updated after every Start of Frame packet receipt.

Important note: the Start of Frame interrupt is generated just after the PID receipt.

Reserved

The value read from this bit is always 0. Do not set this bit.

2-0 FNUM[10:8]

Frame Number

FNUM[10:8] are the upper 3 bits of the 11-bit Frame Number (see the “UFNUML

page 144). It is provided in the last received SOF packet (see SOFINT in the

“USBIEN Register USBIEN (S:BEh) USB Global Interrupt Enable Register” on

page 135). FNUM is updated if a corrupted SOF is received.

76543210

FNUM7 FNUM6 FNUM5 FNUM4 FNUM3 FNUM2 FNUM1 FNUM0

Bit Number

Bit

Mnemonic Description

7 - 0 FNUM[7:0]

Frame Number

FNUM[7:0] are the lower 8 bits of the 11-bit Frame Number (See “UFNUMH

page 144).

1 2 ... 139 140 141 142 143 144 145 146 147 148 149 ... 174 175

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