CS89712 datasheet(15/170 Pages) CIRRUS

15 / 170 page

CS89712

DS502PP2

ignored) of all the bytes in the Reset Configuration

Block, excluding the checksum byte. This sum in-

cludes the Reset Configuration Block header at ad-

dress 00h. Since the checksum is calculated as the

2’s complement of the sum of all preceding bytes in

the Reset Configuration Block, a total of 0 should

result when the checksum value is added to the sum

of the previous bytes.

2.6.6

EEPROM Example

Table 5 shows an example of a Reset Configuration

Block stored in a C46 EEPROM. Note that little-

endian word ordering is used, i.e., the least signifi-

cant word of a multiword datum is located at the

lowest address.

2.6.7

EEPROM Read-out

If the EEDI pin is asserted high at the end of reset,

the Ethernet port reads the first word of EEPROM

data by:

1) Asserting EECS.

2) Clocking out a Read-Register-00h command

on EEDO (EESK provides a 1 MHz serial

clock signal).

3) Clocking the data in on EEDI.

If the EEDI pin is low at the end of the reset signal,

the Ethernet port does not perform an EEPROM

read-out (uses its default configuration).

2.6.7.1

Determining EEPROM Size

The Ethernet port determines the size of the EE-

PROM by checking the sense of EEDI on the tenth

rising edge of EESK. If EEDI is low, the EEPROM

is a ’C46 or ’CS46. If EEDI is high, the EEPROM

is a ’C56, ’CS56, ’C66, or ’CS66.

2.6.7.2

Loading Configuration Data

The Ethernet port reads in the first word from the

EEPROM to determine if configuration data is con-

tained in the EEPROM. If configuration data is not

stored in the EEPROM, the Ethernet port termi-

nates initialization from EEPROM and operates us-

ing its default configuration (See Table 2). If

configuration data is stored in EEPROM, the Ether-

net port automatically loads all configuration data

stored in the Reset Configuration Block into its in-

ternal Ethernet Port registers.

2.6.8

EEPROM Read-out Completion

Once all the configuration data are transferred to

the appropriate Ethernet Port registers, the Ethernet

port performs a checksum calculation to verify the

Reset Configuration Blocks data are valid. If the re-

sulting total is 0, the read-out is considered valid.

Otherwise, the Ethernet port initiates a partial reset

to restore the default configuration.

If the read-out is valid, the EEPROMOK bit

(SelfST register, bit A) is set. EEPROMOK is

3 2

First Word of a Group of Words

F E

Number of Words

in Group

9-bit PacketPage Address

Figure 3. Group Header

CS89712 데이터시트(PDF) 15 Page - Cirrus Logic

CS89712 데이터시트(HTML) 15 Page - Cirrus Logic

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 ...More

데이터시트 다운로드

링크 URL