MC9S12E256 Datasheet, PDF (245/602 Pages) Freescale Semiconductor, Inc – HCS12 Microcontrollers

Chapter 8 Serial Communication Interface (SCIV4)
8.1.3.3 Stop Mode
The SCI is inactive during stop mode for reduced power consumption. The STOP instruction does not
affect the SCI register states, but the SCI bus clock will be disabled. The SCI operation resumes after an
external interrupt brings the CPU out of stop mode. Exiting stop mode by reset aborts any transmission or
reception in progress and resets the SCI.
8.1.4 Block Diagram
Figure 8-1 is a high level block diagram of the SCI module, showing the interaction of various function
blocks.
RXD Data In
Infrared
Decoder
SCI Data Register
Receive Shift Register
IDLE Interrupt Request
IRQ
Generation
Bus Clk
Receive & Wakeup Control
BAUD
Generator
÷16
Data Format Control
Transmit Control
RDRF/OR
Interrupt
Request
TDRE
Interrupt
Request
SCI
Interrupt
Request
Transmit Shift Register
SCI Data Register
IRQ
Generation
TC Interrupt Request
Infrared
Encoder
Data Out TXD
Figure 8-1. SCI Block Diagram
MC9S12E256 Data Sheet, Rev. 1.08
Freescale Semiconductor
245