CYP15G0403DXB_09 Datasheet, PDF(38/45 Page) Cypress Semiconductor – Independent Clock Quad HOTLink II Transceiver

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CYP15G0403DXB_09 Datasheet, PDF (38/45 Pages) Cypress Semiconductor – Independent Clock Quad HOTLink II Transceiver

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CYP15G0403DXB

CYV15G0403DXB

CYW15G0403DXB

After powering on, the Transmitter may assume either a

positive or negative value for its initial running disparity. Upon

transmission of any Transmission Character, the transmitter

selects the proper version of the Transmission Character

based on the current running disparity value, and the Trans-

mitter calculates a new value for its running disparity based on

the contents of the transmitted character. Special Character

codes C1.7 and C2.7 can be used to force the transmission of

a specific Special Character with a specific running disparity

as required for some special sequences in X3.230.

After powering on, the Receiver may assume either a positive

or negative value for its initial running disparity. Upon reception

of any Transmission Character, the Receiver decides whether

the Transmission Character is valid or invalid according to the

following rules and tables and calculates a new value for its

Running Disparity based on the contents of the received

character.

The following rules for running disparity are used to calculate

the new running-disparity value for Transmission Characters

that have been transmitted and received.

Running disparity for a Transmission Character is calculated

from sub-blocks, where the first six bits (abcdei) form one

sub-block and the second four bits (fghj) form the other

sub-block. Running disparity at the beginning of the 6-bit

sub-block is the running disparity at the end of the previous

Transmission Character. Running disparity at the beginning of

the 4-bit sub-block is the running disparity at the end of the

6-bit sub-block. Running disparity at the end of the Trans-

mission Character is the running disparity at the end of the

4-bit sub-block.

Running disparity for the sub-blocks is calculated as follows:

1. Running disparity at the end of any sub-block is positive if

the sub-block contains more ones than zeros. It is also pos-

itive at the end of the 6-bit sub-block if the 6-bit sub-block

is 000111, and it is positive at the end of the 4-bit sub-block

if the 4-bit sub-block is 0011.

2. Running disparity at the end of any sub-block is negative if

the sub-block contains more zeros than ones. It is also

negative at the end of the 6-bit sub-block if the 6-bit

sub-block is 111000, and it is negative at the end of the 4-bit

sub-block if the 4-bit sub-block is 1100.

3. Otherwise, running disparity at the end of the sub-block is

the same as at the beginning of the sub-block.

Use of the Tables for Generating Transmission Characters

The appropriate entry in Table 15 for the Valid Data byte or

Table 16 for Special Character byte identify which Trans-

mission Character is generated. The current value of the

Transmitterâs running disparity is used to select the Trans-

mission Character from its corresponding column. For each

Transmission Character transmitted, a new value of the

running disparity is calculated. This new value is used as the

Transmitterâs current running disparity for the next Valid Data

byte or Special Character byte encoded and transmitted.

Table 13 shows naming notations and examples of valid trans-

mission characters.

Use of the Tables for Checking the Validity of Received

Transmission Characters

The column corresponding to the current value of the

Receiverâs running disparity is searched for the received

Transmission Character. If the received Transmission

Character is found in the proper column, then the Trans-

mission Character is valid and the associated Data byte or

Special Character code is determined (decoded). If the

received Transmission Character is not found in that column,

then the Transmission Character is invalid. This is called a

code violation. Independent of the Transmission Characterâs

validity, the received Transmission Character is used to

calculate a new value of running disparity. The new value is

used as the Receiverâs current running disparity for the next

received Transmission Character.

Table 13.Valid Transmission Characters

Byte Name

Data

DIN or QOUT

765 43210

D0.0

000 00000

Hex Value

D1.0

000 00001

D2.0

000 00010

D5.2

010 00101

D30.7

111 11110

D31.7

111 11111

Detection of a code violation does not necessarily show that

the Transmission Character in which the code violation was

detected is in error. Code violations may result from a prior

error that altered the running disparity of the bit stream which

did not result in a detectable error at the Transmission

Character in which the error occurred. Table 14 shows an

example of this behavior.

Table 14.Code Violations Resulting from Prior Errors

Character

Transmitted data character

D21.1

D10.2

D23.5

Transmitted bit stream

101010 1001

010101 0101

111010 1010

Bit stream after error

101010 1011

010101 0101

111010 1010

Decoded data character

D21.0

D10.2

Code Violation

Document #: 38-02065 Rev. *F

Page 38 of 45

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