S9S12GN32F0MLC Datasheet, PDF (667/1292 Pages) Freescale Semiconductor, Inc – MC9S12G Family Reference Manual and Data Sheet

Serial Communication Interface (S12SCIV5)
20.1.4 Block Diagram
Figure 20-1 is a high level block diagram of the SCI module, showing the interaction of various function
blocks.
RXD Data In
Infrared
Decoder
Bus Clock _{Baud Rate}
Generator
1/16
SCI Data Register
Receive Shift Register
Receive & Wakeup
Control
Data Format Control
Transmit Control
IDLE
Receive
Interrupt ^RDRF/OR
Generation BRKD
RXEDG
BERR
Transmit
Interrupt ^TDRE
Generation TC
SCI
Interrupt
Request
Transmit Shift Register
Infrared
Encoder
Data Out TXD
SCI Data Register
Figure 20-1. SCI Block Diagram
20.2 External Signal Description
The SCI module has a total of two external pins.
20.2.1 TXD — Transmit Pin
The TXD pin transmits SCI (standard or infrared) data. It will idle high in either mode and is high
impedance anytime the transmitter is disabled.
20.2.2 RXD — Receive Pin
The RXD pin receives SCI (standard or infrared) data. An idle line is detected as a line high. This input is
ignored when the receiver is disabled and should be terminated to a known voltage.
20.3 Memory Map and Register Definition
This section provides a detailed description of all the SCI registers.
MC9S12G Family Reference Manual, Rev.1.23
Freescale Semiconductor
669