CY7B923
CY7B933
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.
ceiver’s current running disparity for the next received Trans-
mission Character.
Table 1. Valid Transmission Characters
Data
3. Otherwise, running disparity at the end of the sub-block is
the same as at the beginning of the sub-block.
D
or Q
OUT
IN
Use of the Tables for Generating Transmission Characters
Byte Name
765
43210
Hex Value
The appropriate entry in the table shall be found for the Valid
Data byte or the Special Character byte for which a Transmis-
sion Character is to be generated (encoded). The current val-
ue of the Transmitter’s running disparity shall be used to select
the Transmission Character from its corresponding column.
For each Transmission Character transmitted, a new value of
the running disparity shall be calculated. This new value shall
be used as the Transmitter’s current running disparity for the
next Valid Data byte or Special Character byte to be encoded
and transmitted. Table 1 shows naming notations and examples
of valid transmission characters.
D0.0
000
00000
00
D1.0
D2.0
000
000
00001
00010
01
02
.
.
.
.
.
.
.
.
D5.2
010
00010
1
45
Use of the Tables for Checking the Validity of Received
Transmission Characters
.
.
.
.
.
.
.
.
The column corresponding to the current value of the Receiv-
er’s running disparity shall be searched for the received Trans-
mission Character. If the received Transmission Character is
found in the proper column, then the Transmission 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. Indepen-
dent of the Transmission Character’s validity, the received
Transmission Character shall be used to calculate a new value
of running disparity. The new value shall be used as the Re-
D30.7
D31.7
111
111
11110
11111
FE
FF
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 Char-
acter in which the error occurred. Table 2 shows an example of
this behavior.
Table 2. Code Violations Resulting from Prior Errors
RD
−
Character
D21.1
RD
−
Character
D10.2
RD
−
Character
D23.5
RD
+
Transmitted data character
Transmitted bit stream
Bit stream after error
−
101010 1001
101010 1011
D21.0
−
010101 0101
010101 0101
D10.2
−
111010 1010
111010 1010
Code Violation
+
−
+
+
+
Decoded data character
−
+
+
+
22
CYPRESS [ CYPRESS ]
