MC68HC05B4 Datasheet, PDF (93/298 Pages) Motorola, Inc – High-density Complementary Metal Oxide Semiconductor (HCMOS) Microcomputer Unit

6.13
SCI during STOP mode
When the MCU enters STOP mode, the baud rate generator driving the receiver and transmitter
is shut down. This stops all SCI activity. Both the receiver and the transmitter are unable to operate.
If the STOP instruction is executed during a transmitter transfer, that transfer is halted. When STOP
mode is exited as a result of an external interrupt, that particular transmission resumes.
If the receiver is receiving data when the STOP instruction is executed, received data sampling is
stopped (baud generator stops) and the rest of the data is lost.
Warning: For the above reasons, all SCI transactions should be in the idle state when the STOP
instruction is executed.
6.14
SCI during WAIT mode
6
The SCI system is not affected by WAIT mode and continues normal operation. Any valid SCI
interrupt will wake-up the system. If required, the SCI system can be disabled prior to entering
WAIT mode by writing a zero to the transmitter and receiver enable bits in the serial communication
control register 2 at $000F. This action will result in a reduction of power consumption during WAIT
mode.
MC68HC05B6
Rev. 4
SERIAL COMMUNICATIONS INTERFACE
TPG
MOTOROLA
6-21