MC68HC812A4 Datasheet, PDF (259/342 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)
Modes of Operation
14.9 Modes of Operation
The SCI functions the same in normal, special, and emulation modes.
14.10 Low-Power Options
This section provides a description of the three low-power modes:
• Run mode
• Wait mode
• Stop mode
14.10.1 Run Mode
Clearing the transmitter enable or receiver enable bits (TE or RE) in SCI
control register 2 (SCCR2) reduces power consumption in run mode.
SCI registers are still accessible when TE or RE is cleared, but clocks to
the core of the SCI are disabled.
14.10.2 Wait Mode
The SCI remains active in wait mode. Any enabled interrupt request from
the SCI can bring the MCU out of wait mode.
If SCI functions are not required during wait mode, reduce power
consumption by disabling the SCI before executing the WAIT instruction.
14.10.3 Stop Mode
For reduced power consumption, the SCI is inactive in stop mode. The
STOP instruction does not affect SCI register states. SCI operation
resumes after an external interrupt.
Exiting stop mode by reset aborts any transmission or reception in
progress and resets the SCI.
Advance Information
MOTOROLA
Serial Communications Interface Module (SCI)
MC68HC812A4 — Rev. 3.0
259