Z85233 Datasheet, PDF (65/317 Pages) Zilog, Inc. – The Zilog SCC Serial Communication Controller

SCC™/ESCC™ User’s Manual
SCC/ESCC Ancillary Support Circuitry
3.3 DATA ENCODING/DECODING
Data encoding is utilized to allow the transmission of clock
and data information over the same medium. This saves
the need to transmit clock and data over separate medium
as would normally be required for synchronous data. The
SCC provides four different data encoding methods,
selected by bits D6 and D5 in WR10. An example of these
four encoding methods is shown in Figure 3-3. Any
encoding method is used in any X1 mode in the SCC,
asynchronous or synchronous. The data encoding
selected is active even though the transmitter or receiver
is idling or disabled.
DATA
1
1
NRZ
0
0
1
0
NRZI
FM1
(Biphase Mark)
FM0
(Biphase Space)
MANCHESTER
Bit Cell Level:
High = 1
Low = 0
No Change = 1
Change = 0
Bit Center Transition:
Transition = 1
No Transition = 0
No Transition = 1
Transition = 0
High → Low = 1
Low → High = 0
Figure 3-3. Data Encoding Methods
3-4
UM010901-0601