MC68HC908AP16CFA MOTOROLA [Motorola, Inc], MC68HC908AP16CFA Datasheet - Page 264

• Manufacturer Part Number: MC68HC908AP16CFA
• Description: Microcontrollers
• Manufacturer: MOTOROLA [Motorola, Inc]

Infrared Serial Communications
14.6.3.4 Framing Errors
14.6.3.5 Baud Rate Tolerance
Data Sheet
264
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.
samples.
If the data recovery logic does not detect a logic 1 where the stop bit
should be in an incoming character, it sets the framing error bit, FE, in
IRSCS1. The FE flag is set at the same time that the SCRF bit is set. A
break character that has no stop bit also sets the FE bit.
A transmitting device may be operating at a baud rate below or above
the receiver baud rate. Accumulated bit time misalignment can cause
one of the three stop bit data samples to fall outside the actual stop bit.
Then a noise error occurs. If more than one of the samples is outside the
stop bit, a framing error occurs. In most applications, the baud rate
tolerance is much more than the degree of misalignment that is likely to
occur.
Freescale Semiconductor, Inc.
For More Information On This Product,
Go to: www.freescale.com
RT8, RT9, and RT10
Table 14-4. Stop Bit Recovery
Samples
Table 14-4
000
001
010
011
100
101
110
111
summarizes the results of the stop bit
Error Flag
Framing
1
1
1
0
1
0
0
0
MC68HC908AP Family — Rev. 2.5
Noise Flag
0
1
1
1
1
1
1
0
MOTOROLA