
Enhanced Serial Communications Interface (ESCI) Module
Functional Description
MC68HC908GZ16
Data Sheet
MOTOROLA
Enhanced Serial Communications Interface (ESCI) Module
229
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 Figure 19-7, the receiver counts 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.
With the misaligned character shown in Figure 19-7, the receiver counts 170
RT cycles at the point when the count of the transmitting device is 10 bit
times
× 16 RT cycles + 3 RT cycles = 163 RT cycles.
The maximum percent difference between the receiver count and the
transmitter count of a slow 9-bit character with no errors is:
Fast Data Tolerance
Figure 19-8 shows how much a fast received character can be misaligned
without causing a noise error or a framing error. The fast stop bit ends at RT10
instead of RT16 but is still there for the stop bit data samples at RT8, RT9, and
RT10.
Figure 19-8. Fast Data
For an 8-bit character, data sampling of the stop bit takes the receiver
9bit times
× 16 RT cycles + 10 RT cycles = 154 RT cycles.
With the misaligned character shown in Figure 19-8, the receiver counts 154
RT cycles at the point when the count of the transmitting device is
10 bit times
× 16 RT cycles = 160 RT cycles.
The maximum percent difference between the receiver count and the
transmitter count of a fast 8-bit character with no errors is
154
147
–
154
--------------------------
100
×
4.54%
=
170
163
–
170
--------------------------
100
×
4.12%
=
IDLE OR NEXT CHARACTER
STOP
RT1
RT2
RT3
RT4
RT5
RT6
RT7
RT8
RT9
RT10
RT11
RT12
RT13
RT14
RT15
RT16
DATA
SAMPLES
RECEIVER
RT CLOCK
154
160
–
154
--------------------------
100
×
3.90%.
=
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Freescale Semiconductor, Inc.
For More Information On This Product,
Go to: www.freescale.com
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