
Serial Communications Interface (SCI)
Technical Data
MC68HC908AZ60A — Rev 2.0
258
Serial Communications Interface (SCI)
MOTOROLA
To determine the value of a data bit and to detect noise, recovery logic
takes samples at RT8, RT9, and RT10. Table 18-6 summarizes the
results of the data bit samples.
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.
To verify a stop bit and to detect noise, recovery logic takes samples at
RT8, RT9, and RT10. Table 18-7 summarizes the results of the stop bit
samples.
Table 18-6. Data Bit Recovery
RT8, RT9, and RT10 Samples
Data Bit Determination
Noise Flag
000
0
001
0
1
010
0
1
011
1
100
0
1
101
1
110
1
111
1
0
Table 18-7. Stop Bit Recovery
RT8, RT9, and RT10 Samples
Framing Error Flag
Noise Flag
000
1
0
001
1
010
1
011
0
1
100
1
101
0
1
110
0
1
111
0