mc68hc908gp20 Freescale Semiconductor, Inc, mc68hc908gp20 Datasheet - Page 263

• Manufacturer Part Number: mc68hc908gp20
• Description: M68hc08 Family Of 8-bit Microcontroller Units Mcus
• Manufacturer: Freescale Semiconductor, Inc

MC68HC908GP20
Freescale Semiconductor
—
Rev 2.1
tolerance is much more than the degree of misalignment that is likely to
occur.
As the receiver samples an incoming character, it resynchronizes the RT
clock on any valid falling edge within the character. Resynchronization
within characters corrects misalignments between transmitter bit times
and receiver bit times.
Slow Data Tolerance
Figure 18-7
misaligned without causing a noise error or a framing error. The slow
stop bit begins at RT8 instead of RT1 but arrives in time for the stop bit
data samples at RT8, RT9, and RT10.
For an 8-bit character, data sampling of the stop bit takes the receiver
9 bit times × 16 RT cycles + 10 RT cycles = 154 RT cycles.
With the misaligned character shown in
154 RT cycles at the point when the count of the transmitting device is
9 bit times × 16 RT cycles + 3 RT cycles = 147 RT cycles.
The maximum percent difference between the receiver count and the
transmitter count of a slow 8-bit character with no errors is
For a 9-bit character, data sampling of the stop bit takes the receiver
10 bit times × 16 RT cycles + 10 RT cycles = 170 RT cycles.
RECEIVER
RT CLOCK
shows how much a slow received character can be
MSB
154 147
------------------------- -
Figure 18-7. Slow Data
154
–
×
100
SAMPLES
DATA
Figure
=
4.54%
18-7, the receiver counts
STOP
Advance Information
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