MC68HC812A4 Datasheet, PDF (238/342 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)
START BIT
LSB
RXD
SAMPLES 1 1 1 1 1 1 1 1 0
0
0
0000
RT CLOCK
RT CLOCK COUNT
RESET RT CLOCK
START BIT
QUALIFICATION
START BIT
VERIFICATION
DATA
SAMPLING
Figure 14-6. Receiver Data Sampling
To verify the start bit and to detect noise, data recovery logic takes
samples at RT3, RT5, and RT7. Table 14-4 summarizes the results of
the start bit verification samples.
Table 14-4. Start Bit Verification
RT3, RT5, and RT7 Samples
000
001
010
011
100
101
110
111
Start Bit Verification
Yes
Yes
Yes
No
Yes
No
No
No
Noise Flag
0
1
1
0
1
0
0
0
If start bit verification is not successful, the RT clock is reset and a new
search for a start bit begins.
MC68HC812A4 — Rev. 3.0
238
Serial Communications Interface Module (SCI)
Advance Information
MOTOROLA