5238-DS03-405-R datasheet(63/76 Pages) BOARDCOM

63 / 76 page

Advance Data Sheet

BCM5238

1/31/03

Broa d c om Co rp o r a t i o n

Document

5238-DS03-405-R

Auxiliary Status 4 Register (Shadow Register)

Page 55

AUXILIARY MODE 3 REGISTER (SHADOW REGISTER)

FIFO Size Select [3:0]. The BCM5238 indicates the current selection of receive FIFO size using bit 3 through 0 as shown

in Table 51. The size can also be determined by bit Extended FIFO Enable (register 10h, bit 2) and bit Jumbo Packet Enable

(register 1Bh, bit 9) for backward compatibility with the 0.35

µm products.

AUXILIARY STATUS 4 REGISTER (SHADOW REGISTER)

Packet Length Counter [15:0]. The BCM5238 shows the number of bytes in the last packet received. This is valid only

when a valid link is established.

Table 50: Auxiliary Mode 3 Register (Shadow Register 29d, 1Dh)

BIt

Name

R/W

Description

Default

15:4

Reserveda

a. When writing to this register, preserve existing values of reserved bits by completing a Read/Modify Write.

–

000h

3:0

FIFO Size Select[3:0]

R/W

Currently selected receive FIFO size

0100

Note: R/W = Read/Write, RO = Read only, SC = Self Clear, LL = Latched Low, LH = Latched High, LL and LH Clear

after read operation. Use default values of reserved bit(s) when writing to reserved bit(s). MII shadow register bank 1 is

accessed by setting MII register 1Fh bit 7 to a 1.

Table 51: Current Receive FIFO Size

FIFO Size Select[3:0]

Receive FIFO size in use (Number of Bits)

0000

0001

0010

0011

0100

0101

0110

0111

1000

1001

1010

1011

1100

1101

Table 52: Auxiliary Status 4 Register (Shadow Register 30d, 1Eh)

BIt

Name

R/W

Description

Default

15:0

Packet Length Counter[15:0]

R/O

Number of bytes in the last received packet

0000h

5238-DS03-405-R Datasheet(PDF) 63 Page - Broadcom Corporation.

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