Programming Model

17.4.14.2.5 Truncation

When the receive frame length exceeds 2047 bytes the frame is truncated and the TR bit is set in the receive BD.

17.5 Programming Model

This section gives an overview of the registers, followed by a description of the buffers.

The FEC is programmed by a combination of control/status registers (CSRs) and buffer descriptors. The CSRs are used for mode control and to extract global status information. The descriptors are used to pass data buffers and related buffer information between the hardware and software.

17.5.1 Top Level Module Memory Map

The FEC implementation requires a 1-Kbyte memory map space. This is divided into 2 sections of 512 bytes each. The first is used for control/status registers. The second contains event/statistic counters held in the MIB block. Table 17-9defines the top level memory map.

Table 17-9. Module Memory Map

Address

Function

 

 

IPSBAR + 0x1000-11FF

Control/Status Registers

 

 

IPSBAR + 0x1200-13FF

MIB Block Counters

 

 

17.5.2 Detailed Memory Map (Control/Status Registers)

Table 17-10shows the FEC register memory map with each register address, name, and a brief description.

Table 17-10. FEC Register Memory Map

IPSBAR

Name

Width

Description

Offset

 

 

 

 

 

 

 

0x1004

EIR

32

Interrupt Event Register

 

 

 

 

0x1008

EIMR

32

Interrupt Mask Register

 

 

 

 

0x1010

RDAR

32

Receive Descriptor Active Register

 

 

 

 

0x1014

TDAR

32

Transmit Descriptor Active Register

 

 

 

 

0x1024

ECR

32

Ethernet Control Register

 

 

 

 

0x1040

MDATA

32

MII Data Register

 

 

 

 

0x1044

MSCR

32

MII Speed Control Register

 

 

 

 

0x1064

MIBC

32

MIB Control/Status Register

 

 

 

 

17-20

MCF5282 User’s Manual

MOTOROLA

Page 376
Image 376
Motorola MCF5282 Top Level Module Memory Map, Detailed Memory Map Control/Status Registers, FEC Register Memory Map