MC68HC812A4 Datasheet, PDF (245/342 Pages) Motorola, Inc – 16-bit device composed of standard on-chip peripheral modules connected by an intermodule bus. Modules include

Serial Communications Interface Module (SCI)
Functional Description
For an 8-bit data 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 14-14, 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---5^–---4--1---6---0-- ^{× 100 = 3.90%}
For a 9-bit data 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 14-14, the receiver
counts 170 RT cycles at the point when the count of the transmitting
device is
11 bit times × 16 RT cycles = 176 RT cycles.
The maximum percent difference between the receiver count and the
transmitter count of a fast 9-bit character with no errors is:
-1---7---0--1---7^–---0--1---7---6-- ^{× 100 = 3.53%}
14.6.4.6 Receiver Wakeup
So that the SCI can ignore transmissions intended only for other
receivers in multiple-receiver systems, the receiver can be put into a
standby state. Setting the receiver wakeup bit, RWU, in SCI control
register 2 (SCCR2) puts the receiver into a standby state during which
receiver interrupts are disabled.
The transmitting device can address messages to selected receivers by
including addressing information in the initial frame or frames of each
message.
Advance Information
MOTOROLA
Serial Communications Interface Module (SCI)
MC68HC812A4 — Rev. 3.0
245