Infrared Serial Communications Interface Module (IRSCI)
Table 12-2. Start Bit Verification
RT3, RT5, and RT7
Samples
Start Bit
Verification
Noise Flag
011
100
101
110
111
No
Yes
No
No
No
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 12-3 summarizes the results of the data bit samples.
Table 12-3. Data Bit Recovery
RT8, RT9, and RT10
Samples
Data Bit
Determination
Noise Flag
000
001
010
011
100
101
110
111
0
0
0
1
0
1
1
1
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.
To verify a stop bit and to detect noise, recovery logic takes samples at RT8, RT9, and RT10. Table 12-4
summarizes the results of the stop bit samples.
Table 12-4. Stop Bit Recovery
RT8, RT9, and RT10
Samples
Framing
Error Flag
Noise Flag
000
001
1
1
0
1
MC68HC908AP Family Data Sheet, Rev. 4
192
Freescale Semiconductor
FREESCALE [ Freescale ]
