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.
SCI Data Register
RXD Data In
Infrared
Decoder
Receive Shift Register
IDLE
Receive
Interrupt
Generation
RDRF/OR
BRKD
Receive & Wakeup
Control
SCI
Interrupt
Request
RXEDG
Bus Clock
Baud Rate
Generator
BERR
Data Format Control
Transmit Control
Transmit
Interrupt
Generation
TDRE
TC
1/16
Infrared
Encoder
Data Out TXD
Transmit Shift Register
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
FREESCALE [ Freescale ]
