MC68HC08AS20 Datasheet, PDF (248/386 Pages) Freescale Semiconductor, Inc – M68HC08 Microcontrollers

To verify the start bit and to detect noise, data recovery logic takes
samples at RT3, RT5, and RT7. Table 17-4 summarizes the results of
the start bit verification samples.
Table 17-4. 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.
To determine the value of a data bit and to detect noise, recovery logic
takes samples at RT8, RT9, and RT10. Table 17-5 summarizes the
results of the data bit samples.
Table 17-5. 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
Advance Information
248
MC68HC08AS20 —Rev. 4.1
Freescale Semiconductor