MC68HC812A4 Datasheet, PDF (239/342 Pages) Motorola, Inc – 16-bit device composed of standard on-chip peripheral modules connected by an intermodule bus. Modules include

Serial Communications Interface Module (SCI)
Functional Description
To determine the value of a data bit and to detect noise, recovery logic
takes samples at RT8, RT9, and RT10. Table 14-5 summarizes the
results of the data bit samples.
Table 14-5. Data Bit Recovery
RT8, RT9, and RT10 Samples
000
001
010
011
100
101
110
111
Data Bit Determination
0
0
0
1
0
1
1
1
Noise Flag
0
1
1
1
1
1
1
0
NOTE:
The RT8, RT9, and RT10 samples do not affect start bit verification. If
any or all of the RT8, RT9, and RT10 start bit samples are logic 1s
following a successful start bit verification, the noise flag (NF) is set and
the receiver assumes that the bit is a start bit (logic 0).
To verify a stop bit and to detect noise, recovery logic takes samples at
RT8, RT9, and RT10. Table 14-6 summarizes the results of the stop bit
samples.
Table 14-6. Stop Bit Recovery
RT8, RT9, and RT10 Samples
000
001
010
011
100
101
110
111
Framing Error Flag
1
1
1
0
1
0
0
0
Noise Flag
0
1
1
1
1
1
1
0
Advance Information
MOTOROLA
Serial Communications Interface Module (SCI)
MC68HC812A4 — Rev. 3.0
239