S912XHY128F0VLM Datasheet, PDF (482/802 Pages) Freescale Semiconductor, Inc – S12 Microcontrollers

Serial Communication Interface (S12SCIV5)
To determine the value of a data bit and to detect noise, recovery logic takes samples at RT8, RT9, and
RT10. Table 14-18 summarizes the results of the data bit samples.
Table 14-18. 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 (logic 0).
To verify a stop bit and to detect noise, recovery logic takes samples at RT8, RT9, and RT10. Table 14-19
summarizes the results of the stop bit samples.
Table 14-19. 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
MC9S12XHY-Family Reference Manual, Rev. 1.01
482
Freescale Semiconductor