MC68HC908KX8 Datasheet, PDF (193/310 Pages) Motorola, Inc – Microcontrollers

Serial Communications Interface Module (SCI)
Functional Description
With the misaligned character shown in Figure 14-7, 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
1----5---4-1----5–_{---4-1----4---7-- × 100 = 4.54%}
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 14-7, 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----7–_{---0-1----6---3-- × 100 = 4.12%}
Fast Data Tolerance
Figure 14-8 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.
STOP
IDLE OR NEXT CHARACTER
RECEIVER
RT CLOCK
DATA
SAMPLES
Figure 14-8. 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.
MC68HC908KX8 • MC68HC908KX2 • MC68HC08KX8 — Rev. 1.0
MOTOROLA
Serial Communications Interface Module (SCI)
Technical Data
193