MC908AB32CFUE Datasheet, PDF (256/392 Pages) Freescale Semiconductor, Inc – Microcontrollers

Serial Communications Interface
With the misaligned character shown in Figure 15-7, 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
1----7---0-----–_{-----1---6---3-- × 100 = 4.12%}
170
Fast Data Tolerance
Figure 15-8 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.
RECEIVER
RT CLOCK
STOP
IDLE OR NEXT CHARACTER
DATA
SAMPLES
Figure 15-8. Fast Data
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 15-8, 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
1----5---4-----–_{-----1---6---0-- × 100 = 3.9}^·_0%
154
Technical Data
256
MC68HC908AB32 — Rev. 1.1
Serial Communications Interface Module (SCI)
Freescale Semiconductor