MC68HC908GT16_07 Datasheet, PDF (151/292 Pages) Freescale Semiconductor, Inc – Microcontrollers

Functional Description
14.4 Functional Description
Figure 14-2 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. During
normal operation, the CPU monitors the status of the ESCI, writes the data to be transmitted, and
processes received data.
For reference, a summary of the ESCI module input/output registers is provided in Figure 14-4.
INTERNAL BUS
ESCI DATA
REGISTER
RxD
RECEIVE
SHIFT REGISTER
LINR
SCTIE
TCIE
SCRIE
ILIE
TE
RE
RWU
SBK
SCTE
TC
SCRF
IDLE
WAKEUP
CONTROL
ESCI DATA
REGISTER
RxD
TRANSMIT
SHIFT REGISTER
ARBITER- TxD
SCI_TxD
TXINV
R8
T8
OR
NF
FE
PE
LOOPS
RECEIVE
CONTROL
FLAG
CONTROL
LOOPS
ENSCI
ORIE
NEIE
FEIE
PEIE
TRANSMIT
CONTROL
BKF
ENSCI
RPF
PRE-
SCALER
÷4
PRE- BAUD RATE
SCALER GENERATOR
M
LINT
WAKE
ILTY
PEN
PTY
÷ 16
DATA SELECTION
CONTROL
Figure 14-2. ESCI Module Block Diagram
MC68HC908GT16 • MC68HC908GT8 • MC68HC08GT16 Data Sheet, Rev. 5.0
Freescale Semiconductor
151