Datasheet

Serial Communications Interface (SCI)
MC9S12DP256 — Revision 1.1
Serial Communications Interface (SCI)
Table 72 Stop Bit Recovery
In Figure 69, the verification samples RT3 and RT5 determine that the
first low detected was noise and not the beginning of a start bit. The RT
clock is reset and the start bit search begins again. The noise flag is not
set because the noise occurred before the start bit was found.
Figure 69 Start Bit Search Example 1
In Figure 70, verification sample at RT3 is high. The RT3 sample sets
the noise flag. Although the perceived bit time is misaligned, the data
samples RT8, RT9, and RT10 are within the bit time and data recovery
is successful.
RT8, RT9, and RT10 Samples Framing Error Flag Noise Flag
000 1 0
001 1 1
010 1 1
011 0 1
100 1 1
101 0 1
110 0 1
111 0 0
RESET RT CLOCK
RT1 RT1 RT1 RT1 RT2 RT3 RT4 RT5 RT1 RT1 RT2 RT3 RT4 RT7 RT6 RT5
RT10
RT9 RT8
RT14 RT13 RT12 RT11 RT15 RT16
RT1 RT2 RT3
SAMPLES
RT CLOCK
RT CLOCK COUNT
START BIT
sci_rx_ind
110111100000
LSB
0 0
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