Programming Model

 

Table 17-30. TFWR Field Descriptions

 

 

 

 

 

Bits

Name

 

Descriptions

 

 

 

 

 

31–2

Reserved, should be cleared.

 

 

 

 

 

1–0

X_WMRK

Number of bytes written to transmit FIFO before transmission

 

 

 

of a frame begins

 

 

 

0x

64 bytes written

 

 

 

10

128 bytes written

 

 

 

11

192 bytes written

 

 

 

 

 

 

17.5.4.19 FIFO Receive Bound Register (FRBR)

The FRBR is an 8-bit register that the user can read to determine the upper address bound of the FIFO RAM. Drivers can use this value, along with the FRSR to appropriately divide the available FIFO RAM between the transmit and receive data paths.

Field

Reset

R/W

Field

Reset

R/W Address

31

16

0000_0000_0000_0000

Read Only

15

10

9

2

1

0

 

 

R_BOUND

 

 

 

 

 

 

 

0000_0110_0000_0000

Read Only

IPSBAR + 0x114C

Figure 17-22. FIFO Receive Bound Register (FRBR)

Table 17-31. FRBR Field Descriptions

Bits

Name

Descriptions

 

 

 

31–10

Reserved, read as 0 (except bit 10, which is read as 1).

 

 

 

9–2

R_BOUND

Read-only. Highest valid FIFO RAM address.

 

 

 

1–0

Reserved, should be cleared.

 

 

 

MOTOROLA

Chapter 17. Fast Ethernet Controller (FEC)

17-41

Page 397
Image 397
Motorola MCF5281, MCF5282 user manual Fifo Receive Bound Register Frbr, Tfwr Field Descriptions, Rbound