HD64570 Datasheet, PDF (35/469 Pages) Hitachi Semiconductor – Serial Communications Adaptor

1.7.4 Transmission Codes
The SCA supports five transmission codes: NRZ, NRZI, FM0, FM1, and Manchester (figure 1.8).
See figures 5.39, 5.40, and 5.41 for the timing relationships between the TX and RX clocks and
each code.
Type No. Code
NRZ 1
Enco-
ding
NRZ
(Nonreturn to
zero)
2 NRZI
(Nonreturn to
zero inversion)
FM 1
Enco-
ding
FM0
(Frequency
modulation
space)
2 FM1
(Frequency
modulation
mark)
3 MANCHESTER
(Manchester)
Data and waveform
01
0
0
1
1
Definition of 1 and 0
1: High
0: Low
1: No transition
0: Transition
1: Transition at
beginning of bit cell
0: Transitions at
beginning and center
of bit cell
1: Transitions at
beginning and center
of bit cell
0: Transition at
beginning of bit cell
1: High-to-low transition
at center of bit cell
0: Low-to-high transition
at center of bit cell
Figure 1.8 Transmission Codes
Rev. 0, 07/98, page 19 of 453