Kawasaki 80C152 - Manual (Page 61)

KS152JB Universal Communications Controller
Technical Specifications
Kawasaki LSI USA, Inc. Page 61 of 120 Ver. 0.9 KS152JB2
age and currents that the GSC is capable of providing are the same levels as those for normal port
operation. The signal used to enable the external drivers is DEN. No similar signal is needed for
the receiver.
DEN is active one bit time before transmission begins. In CSMA/CD DEN remains active for two
bit times after the CRC is transmitted. In SDLC DEN remains active until the last bit of the EOF
is transmitted.
3.5.8 JITTER (RECEIVE)
Data jitter is the difference between the actual transmitted waveform and the exact calculated
value(s). In NRZI, data jitter would be how much the actual wave-form exceeds or falls short of
one calculated bit time. A bit time equal 1/ baud rate. If using Manchester encoding, there can be
two transitions during one bit time as shown in Figure below. This causes a second parameter to
be considered when trying to figure out the complete data jitter amount. This other parameter is
the half-bit jitter.The half-bit jitter is comprised of the difference in time that the half-bit transition
actually occurs and the calculated value. Jitter is important because if the transition occurs too
soon it is considered noise, and if the transition occurs too late, then either the bit is missed or a
collision is assumed.