Datasheet

Chapter 8 Serial Communication Interface (SCIV3)
MC9S12E128 Data Sheet, Rev. 1.07
258 Freescale Semiconductor
8.4 Functional Description
This subsection provides a complete functional description of the SCI block, detailing the operation of the
design from the end user’s perspective in a number of descriptions.
Figure 8-11 shows the structure of the SCI module. The SCI allows full duplex, asynchronous, serial
communication between the CPU and remote devices, including other CPUs. The SCI transmitter and
receiver operate independently, although they use the same baud rate generator. The CPU monitors the
status of the SCI, writes the data to be transmitted, and processes received data.
Figure 8-11. Detailed SCI Block Diagram
SCI DATA
RECEIVE
SHIFT REGISTER
SCI DATA
REGISTER
TRANSMIT
SHIFT REGISTER
REGISTER
BAUD RATE
GENERATOR
SBR12–SBR0
BUS
TRANSMIT
CONTROL
÷16
RECEIVE
AND WAKEUP
DATA FORMAT
CONTROL
CONTROL
T8
PF
FE
NF
RDRF
IDLE
TIE
OR
TCIE
TDRE
TC
R8
RAF
LOOPS
RWU
RE
PE
ILT
PT
WAKE
M
CLOCK
ILIE
RIE
RXD
RSRC
SBK
LOOPS
TE
RSRC
IREN
R16XCLK
Ir_RXD
TXD
Ir_TXD
R16XCLK
R32XCLK
TNP[1:0]
IREN
TRANSMIT
ENCODER
RECEIVE
DECODER
SCRXD
SCTXD
INFRARED
INFRARED
TC
TDRE
RDRF/OR
IDLE
SCI
Interrupt
Request