MC68HC908QB8 Datasheet, PDF (111/236 Pages) Freescale Semiconductor, Inc – To provide the most up-to-date information, the revision of our documents

Functional Description
13.3 Functional Description
Figure 13-2 shows the structure of the ESCI module. The ESCI allows full-duplex, asynchronous, NRZ
serial communication between the MCU and remote devices, including other MCUs. The transmitter and
receiver of the ESCI operate independently, although they use the same baud rate generator.
INTERNAL BUS
BUS
CLOCK
CGMXCLK
ESCI DATA
REGISTER
RxD
RECEIVE
SHIFT REGISTER
ESCI DATA
REGISTER
RxD
SCI_TxD
TRANSMIT
TxD
SHIFT REGISTER
LINR
SCTIE
TCIE
SCRIE
ILIE
TE
RE
RWU
SBK
SCTE
TC
SCRF
IDLE
WAKEUP
CONTROL
TXINV
R8
T8
BUS_CLK
SL
ACLK BIT
IN SCIACTL
OR
NF
FE
PE
LOOPS
LOOPS
ENSCI
ORIE
NEIE
FEIE
PEIE
RECEIVE
CONTROL
FLAG
CONTROL
TRANSMIT
CONTROL
BKF
ENSCI
ENHANCED
RPF
PRESCALER
SL
÷4
PRE- BAUD RATE
SCALER GENERATOR
M
LINT
WAKE
ILTY
PEN
PTY
÷ 16
DATA SELECTION
CONTROL
SL = 1 -> SCI_CLK = BUSCLK
SL = 0 -> SCI_CLK = CGMXCLK (4x BUSCLK)
Figure 13-2. ESCI Module Block Diagram
MC68HC908QB8 Data Sheet, Rev. 1
Freescale Semiconductor
111