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 13-2 summarizes the results of the data
bit samples.
Table 13-2. Data Bit Recovery
RT8, RT9, and RT10
Samples
Data Bit
Determination
Noise Flag
000
001
010
011
100
101
110
111
0
0
0
1
0
1
1
1
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 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 13-3 summarizes the results of the stop bit samples.
Table 13-3. Stop Bit Recovery
RT8, RT9, and RT10
Samples
Framing
Error Flag
Noise Flag
000
001
010
011
100
101
110
111
1
1
1
0
1
0
0
0
0
1
1
1
1
1
1
0
MC68HC908MR32 • MC68HC908MR16 — Rev. 6.0
MOTOROLA Serial Communications Interface Module (SCI)
Data Sheet
179
FREESCALE [ Freescale ]
