MC68HC08AS32 Datasheet, PDF (166/280 Pages) Motorola, Inc – M68HC08 Family of 8-bit microcontroller units (MCUs)

To determine the value of a data bit and to detect noise, recovery logic takes
samples at RT8, RT9, and RT10. Table 12-3 summarizes the results of the data
bit samples.
Table 12-3. 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.
To verify a stop bit and to detect noise, recovery logic takes samples at RT8, RT9,
and RT10. Table 12-4 summarizes the results of the stop bit samples.
Table 12-4. 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
Data Sheet
166
MC68HC08AS32 — Rev. 4.1
Freescale Semiconductor