Freescale Semiconductor MPC5200B ユーザーズマニュアル

15-66

Freescale Semiconductor

This data format is similar to the UART. Each data consists of a start bit, 8 bit data and a stop bit. Each bit data is encoded so that a 0 is encoded 
as 3/16 of the bit time pulse (or 1.6 

µs pulse) and a 1 is encoded as no pulse. Similarly, the received serial pulse is decoded as a 0 and an 

absence of a pulse is decoded as a 1. Like the UART mode, the SIR mode sends the lsb first. Here is an example of data stream of UART and 
SIR.

Please choose first the desired mode (SIR mode) than configure the port (write to port_config 
register). This sequence will avoid pulses on the TX line during port configuration. This is very 
important for all IrDA (SIR, MIR, and FIR) modes.

For more informations regarding the pulse width and Baud rate calculations see 

 

Section 15.2.12, Counter Timer Upper Register (0x18)—CTUR.

IRDA_TX

Transmitter Serial Data Output—Transfers must be specified as msb first.

IRDA_RX

Receiver Serial Data Input—Transfers must be specified as msb first.

Receiver

Transmitter

Rx FIFO

Tx FIFO

Clock

 

Generation
Unit

IRDA_RX

IRDA_TX

External
Interface
Signals

IPB Clock

IPB 
Interface

CommBus 
Interface

IRQ

 

Controller

BestComm

Request

PSC

{CTUR:CTLR}

start
bit

data bits(8 bit)

UART data
format

SIR data
format

0

1

0

1

0

1

1

0

0

1

stop
bit

3/16 of the bit width
or 1.6 

µs

lsb

msb