MC68HC812A4 Datasheet, PDF (241/342 Pages) Motorola, Inc – 16-bit device composed of standard on-chip peripheral modules connected by an intermodule bus. Modules include

Serial Communications Interface Module (SCI)
Functional Description
In Figure 14-9 a large burst of noise is perceived as the beginning of a
start bit, although the test sample at RT5 is high. The RT5 sample sets
the noise flag. Although this is a worst-case misalignment of perceived
bit time, the data samples RT8, RT9, and RT10 are within the bit time
and data recovery is successful.
Figure 14-10 shows the effect of noise early in the start bit time.
Although this noise does not affect proper synchronization with the start
bit time, it does set the noise flag.
PERCEIVED START BIT
ACTUAL START BIT
LSB
RXD
SAMPLES 1 1 1 0
0
1
0000
RT CLOCK
RT CLOCK COUNT
RESET RT CLOCK
Figure 14-9. Start Bit Search Example 3
PERCEIVED AND ACTUAL START BIT
LSB
RXD
SAMPLES 1 1 1 1 1 1 1 1 1 0
1
0
RT CLOCK
RT CLOCK COUNT
RESET RT CLOCK
Figure 14-10. Start Bit Search Example 4
Advance Information
MOTOROLA
Serial Communications Interface Module (SCI)
MC68HC812A4 — Rev. 3.0
241