mc68hc908gr8vp Freescale Semiconductor, Inc, mc68hc908gr8vp Datasheet - Page 170

• Manufacturer Part Number: mc68hc908gr8vp
• Description: M68hc08 Microcontrollers Microcontroller
• Manufacturer: Freescale Semiconductor, Inc

Serial Communications Interface (SCI)
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.
To verify a stop bit and to detect noise, recovery logic takes samples at RT8, RT9, and RT10.
summarizes the results of the stop bit samples.
18.4.3.4 Framing Errors
If the data recovery logic does not detect a 1 where the stop bit should be in an incoming character, it sets
the framing error bit, FE, in SCS1. A break character also sets the FE bit because a break character has
no stop bit. The FE bit is set at the same time that the SCRF bit is set.
170
Table 18-3
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 1s following a
successful start bit verification, the noise flag (NF) is set and the receiver
assumes that the bit is a start bit.
RT8, RT9, and RT10 Samples
RT3, RT5, and RT7 Samples
summarizes the results of the data bit samples.
RT8, RT9, and RT10
Samples
000
001
010
011
100
101
110
111
Table 18-2. Start Bit Verification (Continued)
101
110
111
MC68HC908GR8 • MC68HC908GR4 Data Sheet, Rev. 7
000
001
010
011
100
101
110
111
Table 18-4. Stop Bit Recovery
Table 18-3. Data Bit Recovery
NOTE
Data Bit Determination
Verification
Start Bit
Error Flag
Framing
No
No
No
0
0
0
1
0
1
1
1
1
1
1
0
1
0
0
0
Noise Flag
Noise Flag
Noise Flag
0
1
1
1
1
1
1
0
0
0
0
0
1
1
1
1
1
1
0
Freescale Semiconductor
Table 18-4