MPC821 datasheet(43/242 Pages) NXP

43 / 242 page

Functional Description

MPC8XXFADS Design Specification—Rev 0.1

PRELIMINARY—SUBJECT TO CHANGE WITHOUT NOTICE

mined according to the MPC typeB.

To allow alternative use of the I/R’s SCC or its pins, the infra-red transceiver may be disabled /

enabled at any time, by writing ’1’ / ’0’ to the IrdEn~ bit in BCSR1, while all pins appear on the

daughter-board expansion connector, as well as on P8 of this board.

4•9•2•1

Infra-Red Port Rate Range Selection

The TFDS6000 has 2 bit-rate ranges:

9600 Bps to 1.2 MBps

1.2 MBps to 4 MBps.

Selection between the 2 ranges is determined by the state of the transceiver’s TX input on the falling

edge of IrdEn~.

When TX input is LOW at least 200 nsec before the falling edge of IrdEn~, then, the LOWER range

is selected. If TX is HIGH for that period of time, then, the HIGHER range is selected.

4•9•3

RS232 Ports

To assist user’s applications and to provided convenient communication channels with both a

terminal and a host computer, two identical RS232 ports are provided on the FADS. The MPC’s com-

munication ports to which these RS232 ports is routed, is established according to the type of MPC

residing on the daughter board. Use is done with MC145707 transceivers which generates RS232

levels internally using a single 5V supply and are equipped with OE and shutdown mode. When the

RS232EN1 or RS232EN2 bits in BCSR1 are asserted (low), the associated transceiver is enabled.

When negated, the associated transceiver enters standby mode, in which the receiver outputs are tri-

stated, enabling use of the associated port’s pins, off-board via the expansion connectors.

Use is done with 9 pins, female D-Type stacked connector, configured to be directly (via a flat cable)

connected to a standard IBM-PC like RS232 connector.

FIGURE 4-5 RS232 Serial Ports’ Connector

4•9•3•1

RS-232 Ports’ Signal Description

In the list below, the directions ’I’, ’O’, and ’I/O’ are relative to the FADS board. (I.e. ’I’ means input to

the FADS)

•

CD ( O ) - Data Carrier Detect. This line is always asserted by the FADS.

•

TX ( O ) - Transmit Data.

•

RX ( I ) - Receive Data.

•

DTR ( I ) - Data Terminal Ready. This signal may be used by the software on the FADS to

detect if a terminal is connected to the FADS board.

•

DSRA ( O ) - Data Set Ready. This line is always asserted by the FADS.

•

RTS ( I ) - Request To Send. This line is not connected in the FADS.

•

CTS ( O ) - Clear To Send. This line is always asserted by the FADS.

A. Since there are only 3 RS232 transmitters in the device, DSR is connected to CD.

RTS

CTS

DSR

GND

DCD

N.C.

DTR

Freescale Semiconductor, Inc.

For More Information On This Product,

Go to: www.freescale.com

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