CS89712 datasheet(13/170 Pages) CIRRUS

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CS89712

DS502PP2

2.6.3.1

Reset Configuration Block Structure

The Reset Configuration Block is a block of contig-

uous 16-bit words starting at EEPROM address

00h. It can be divided into three logical sections: a

header, one or more groups of configuration data

words, and a checksum value. All words in the Re-

set Configuration Block are read sequentially by

the Ethernet port after each reset, starting with the

header and ending with the checksum. Each group

of configuration data is used to program an Ether-

Word Address

Value

Description

FIRST WORD in DATA BLOCK

00h

A120h

Configuration Block Header.

The high byte, A1h, indicates a ‘C46 EEPROM is attached. The Link

Byte, 20h, indicates the number of bytes to be used in this block of config-

uration data.

FIRST GROUP of WORDS

01h

2020h

Group Header for first group of words.

Three words to be loaded, beginning at 0020h in Ethernet Port memory.

02h

0300h

I/O Base Address

03h

0003h

Interrupt Number

04h

0001h

DMA Channel Number

SECOND GROUP of WORDS

05h

502Ch

Group Header for second group of words.

Six words to be loaded, beginning at 002Ch in Ethernet Port memory.

06h

E000h

Memory Base Address - low word

000Fh

Memory Base Address - high word

08h

0000h

Boot PROM Base Address - low word

09h

000Dh

Boot PROM Base Address - high word

0Ah

C000h

Boot PROM Address Mask - low word

0Bh

000Fh

Boot PROM Address Mask - high word

THIRD GROUP of WORDS

0Ch

2158h

Group Header for third group of words.

Three words to be loaded, beginning at 0158 in Ethernet Port memory.

0Dh

0010h

Individual Address - Octet 0 and 1

0Eh

0000h

Individual Address - Octet 2 and 3

0Fh

0000h

Individual Address - Octet 4 and 5

CHECKSUM Value

10h

2800h

The high byte, 28h, is the Checksum Value. In this example, the check-

sum includes word addresses 00h through 0Fh. The hexadecimal sum of

the bytes is D8h, resulting in a 2’s complement of 28h. The low byte, 00h,

provides a pad to the word boundary.

Note:

FFFFh is a special code indicating that there are no more words in the EEPROM.

Table 5. EEPROM Configuration Block Example

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