MC68HC908KX8 Datasheet, PDF (191/310 Pages) Motorola, Inc – Microcontrollers

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 14-3 summarizes the
results of the data bit samples.
Table 14-3. 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 14-4 summarizes the results of the stop bit
samples.
Table 14-4. 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
MC68HC908KX8 • MC68HC908KX2 • MC68HC08KX8 — Rev. 1.0
MOTOROLA
Serial Communications Interface Module (SCI)
Technical Data
191