DP83256VF-AP NSC [National Semiconductor], DP83256VF-AP Datasheet - Page 17

• Manufacturer Part Number: DP83256VF-AP
• Manufacturer: NSC [National Semiconductor]

3-7 )
3 0 Functional Description
INJECTION CONTROL LOGIC
The Injection Control Logic replaces the data stream with a
programmable symbol pair This function is used to transmit
data other than the normal data frame or Line States The
injection modes can be used for station diagnostic software
The Injection Symbols overwrite the Line State Generator
(Transmit Modes) and the Repeat Filter and Smoother out-
puts
These programmable symbol pairs are stored in the Injec-
tion Symbol Register A (ISRA) and Injection Symbol Regis-
ter B (ISRB) The Injection Threshold Register (IJTR) deter-
mines where the Injection Symbol pair will replace the data
symbols
The Injection Control Logic is programmed through the bits
0 and 1 (IC
(CTSR) to one of the following Injection Modes (see Figure
1 No Injection (i e normal operation)
2 One Shot
3 Periodic
4 Continuous
In the No Injection mode the data stream is transmitted
unchanged
One Shot (Notes 1 3)
Periodic (Notes 2 3)
Continuous (Note 3)
Note 1 In one shot when n
Note 2 In periodic when n
Note 3 Max value on n
k
1 0
l
) of the Current Transmit State Register
e
255
e
e
0 all symbols are replaced
0 the JK is replaced
(Continued)
FIGURE 3-7 Injection Modes
17
In the One Shot mode ISRA and ISRB are injected once on
the nth byte after a JK where n is the programmed value
specified in the Injection Threshold Register
In the Periodic mode ISRA and ISRB are injected every nth
symbol
In the Continuous mode all data symbols are replaced with
the content of ISRA and ISRB This is the same as periodic
mode with IJTR
SHIFT REGISTER
The Shift Register converts encoded parallel data to serial
data The parallel data is clocked into the Shift Register by
the Local Byte Clock (LBC1) and clocked out by the Trans-
mit Bit Clock (TXC
NRZ TO NRZI ENCODER
The NRZ to NRZI Encoder converts the serial Non-Return-
To-Zero data to Non-Return-To-Zero-Invert-On-One format
This function can be enabled and disabled through bit 6
(TNRZ) of the Mode Register (MR) When programmed to
‘‘0’’ it converts the bit stream from NRZ to NRZI When
programmed to ‘‘1’’ the bit stream is transmitted NRZ
e
0
g
) (externally available on the DP83257 )
TL F 11708 – 10
TL F 11708 – 8
TL F 11708 – 9