CDB8952 Просмотр технического описания (PDF) - Cirrus Logic

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CDB8952

CrystalLAN™ 100BASE-X and 10BASE-T Transceiver

Cirrus Logic 

CS8952T

CrystalLAN™ 100BASE-X and 10BASE-T Transceiver

Name

5-bit Symbol

CONTROL (Note 1)

I

11111

J

11000

K

10001

T

01101

R

00111

CODE VIOLATIONS

H

00100

V0

00000

V1

00001

V2

00010

V3

00011

V4

00101

V5

00110

V6

01000

V7

01100

V8

10000

V9

11001

Code Violations (RX_ER = 1 or TX_ER = 1)

Error Report

Normal Mode 4-bit Mode 4-bit

Nibble

Nibble

Comments

0000

0000

0000

0000

0000

0000

0000

0000

0000

0000

This portion of the table relates received

5-bit symbols to received 4-bit nibbles

only. The control code groups may not

be transmitted in the data portion of the

frame.

0000

0110 or 0101 (Note 2)

0110 or 0101 (Note 2)

0110 or 0101 (Note 2)

0110 or 0101 (Note 2)

0110 or 0101 (Note 2)

0110 or 0101 (Note 2)

0110 or 0101 (Note 2)

0110 or 0101 (Note 2)

0110 or 0101 (Note 2)

0110 or 0101 (Note 2)

0000

0001

0111

1000

1001

1010

1011

1100

1101

1110

1111

1. CONTROL code groups become violations when found in the data portion of the frame.

2. Invalid code groups are mapped to 5h unless the Code Error Report select bit in the Loopback,

Bypass, and Receiver Error Mask Register (address 18h) is set, in which case invalid code groups are

mapped to 6h.

Table 3. 4B5B Code Violation Decoding

Carrier Sense Operation

The CRS pin (Carrier Sense) is asserted when ei-

ther the transmitter is active or the receiver detects

at least two non-contiguous ZEROS within any 10

bits in the received data stream. Once asserted, it

will remain asserted until the transmitter has gone

idle or the receiver detects 10 consecutive ONES.

CRS is not synchronous to RX_CLK. It may tran-

sition at any time.

Link Integrity Monitor

The link integrity monitor determines whether the

underlying receive channel is providing reliable

data.

When auto-negotiation is disabled, the link is con-

sidered to be stable when the receiver has detected

valid signal levels for at least 1 ms. If the signal

levels fall below the minimum for more than

350 us, the Link Status bit in the Basic Mode Status

Register (address 01h) is cleared, the Link Status

Change bit in the Interrupt Status Register (address

11h) is set, and the Disconnect Count Register (ad-

dress 12h) is incremented.

When auto-negotiation is enabled, the link will be

further qualified by the detection 100BASE-X

mode and 12 consecutive IDLE code groups.

Collision Detection

For half duplex, a collision is detected when the re-

ceiver and transmitter are active simultaneously.

Collisions are reported by asserting the COL pin.

CIRRUS LOGIC ADVANCED PRODUCT DATABOOK

DS206TPP2

19

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