MC9S12P128_10 Datasheet, PDF (365/566 Pages) Freescale Semiconductor, Inc – S12 Microcontrollers

Serial Communication Interface (S12SCIV5)
11.1.4 Block Diagram
Figure 11-1 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 11-1. SCI Block Diagram
11.2 External Signal Description
The SCI module has a total of two external pins.
11.2.1 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.
11.2.2 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.
11.3 Memory Map and Register Definition
This section provides a detailed description of all the SCI registers.
S12P-Family Reference Manual, Rev. 1.13
Freescale Semiconductor
365