MC68HC908GR4MP datasheet(175/286 Pages) FREESCALE

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I/O Registers

MC68HC908GR8 • MC68HC908GR4 Data Sheet, Rev. 7

Freescale Semiconductor

175

18.7.2 PE1/RxD (Receive Data)

The PE1/RxD pin is the serial data input to the SCI receiver. The SCI shares the PE1/RxD pin with port E.

When the SCI is enabled, the PE1/RxD pin is an input regardless of the state of the DDRE1 bit in data

direction register E (DDRE).

18.8 I/O Registers

These I/O registers control and monitor SCI operation:

•

SCI control register 1 (SCC1)

•

SCI control register 2 (SCC2)

•

SCI control register 3 (SCC3)

•

SCI status register 1 (SCS1)

•

SCI status register 2 (SCS2)

•

SCI data register (SCDR)

•

SCI baud rate register (SCBR)

18.8.1 SCI Control Register 1

SCI control register 1:

•

Enables loop mode operation

•

Enables the SCI

•

Controls output polarity

•

Controls character length

•

Controls SCI wakeup method

•

Controls idle character detection

•

Enables parity function

•

Controls parity type

LOOPS — Loop Mode Select Bit

This read/write bit enables loop mode operation. In loop mode the PE1/RxD pin is disconnected from

the SCI, and the transmitter output goes into the receiver input. Both the transmitter and the receiver

must be enabled to use loop mode. Reset clears the LOOPS bit.

1 = Loop mode enabled

0 = Normal operation enabled

Address:

$0013

Bit 7

654321

Bit 0

Read:

LOOPS

ENSCI

TXINV

WAKE

ILTY

PEN

PTY

Write:

Reset:

00000000

Figure 18-9. SCI Control Register 1 (SCC1)

MC68HC908GR4MP Datasheet(PDF) 175 Page - Freescale Semiconductor, Inc

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