AX88780 datasheet(14/49 Pages) ASIX

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AX88780

3.10 16-bit Mode

AX88780 supports 16-bit mode operation. AX88780 will request a 16K bytes space for TX, RX and register access. The

mapping mechanism can refer to below block. Firstly, the driver requests a 16K bytes space from system then sets the new

mapped address to base + 6 to remap window base. Secondly, driver sets base address to ‘1’ to start decoding.

MEMBASE--Memory base Address

Field

Name

Type

Default

Description

15:1

R/W

All 0’s

Reserved.

DECODE_EN

R/W

16-bit decode enable

Set to ‘1’ to start decoding.

MEMBAS6--Memory base Address + 6

Field

Name

Type

Default

Description

15:8

R/W

8’h00

Reserved.

7:0

WINSIZE R/W

8’h00

Window Base Pointer. (MSB only)

This field defines another new windows base address for TX, RX and register

access. The total size is 8K bytes.

TX areas occupy 4K – 256 bytes

Registers occupy 256 bytes.

RX areas occupy 4K bytes.

Note: This address defines the window used in TX, RX and registers accessed in 16-bit mode. Refer to below mapping

mechanism.

Ba s e a d d r e s s

B a se a d d r e s s + 6

Ne w b a s e Ad d r e s s = 1 6 ’ h XX0 0

TX a r e a

3 840 b y t e s

R e gi s t er a r ea

25 6 b y t e s

Rx a r e a

4 096 b y t e s

4K b y t e s

8K b y t e s

16 K b y t e s

Figure 5 : 16-bit mode map block

Next example is to explain the address translation. If the starting address 24’h20_0000 is allocated to hardware then

driver sets 16’h1000 to address 24’h20_0006. The new base address will be 24’h20_1000 now. The TX areas will be

from 24’20_1000 to 24’h20_1EFF. The registers range will be from 24h20_1F00 to 24’h20_1FFF. The RX areas will be

from 24’h20_2000 to 24’h20_2FFF.

3.11 EEPROM Format

AX88780 will auto-load data from EEPROM device after hardware reset. If the EEPROM device is not attached, the

loading operation will be discarded. The EEPROM mainly provides MAC address information and CIS information if it is

used in PCMCIA environment. Below table is the format if EEPROM device is employed. Note: If the address of MAC is

48’h123456789ABC then the MACID0 will be 16’h9ABC, MACID1=16h’h5678 and MACID2=16’h1234.

ASIX ELECTRONICS CORPORATION

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