XE900 Просмотр технического описания (PDF) - Xecom

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XE900

Miniature Spread Spectrum Transceiver

Xecom 

XE900SL10 COMMUNICATIONS CONTROLLER

The XE900SL10 uses an internal micro-controller to

control communications. This micro-controller manages

the interface to the host system, determines when the

communications link is available, and formats data for

the RF communications.

HOST INTERFACE

There are two primary interfaces between the XE900SL10

and the system host; the serial interface and the direct

sensor interface supported by the SensorOnAir™

feature. Management of both interfaces is the

responsibility of the communications controller.

Serial Interface

A 4-signal serial interface links the host to the XE900SL10.

For most applications the XE900SL10 acts as a DCE.

Control and configuration of the XE900SL10 takes place

through the serial interface using modem-like AT

commands. Serial data rates from 1200 bits per second to

115.2K bits per second are supported. The serial interface

signals are listed below.

/TXD - Transmit Data; the input to the XE900SL10 for

AT commands and Data to be transmitted on the

wireless network.

/RXD - Received Data; the output from the XE900SL10

for received RF data and responses to AT

commands.

/RTS -

Request to Send, provides the hardware flow

control input to the XE900SL10. The DTE

deactivates /RTS to stop the XE900SL10 from

sending more data on the RXD line.

/CTS - Clear to Send, is the hardware flow control output

from the XE900SL10. The XE900SL10 deactivates

/CTS to advise the host to stop inputting data

on the TXD lead.

XE900SL10 AT Command Format

AT commands issued to the XE900SL10 follow a strict

format. Each command begins with the prefix AT and

ends with a carriage return. The XE900SL10

communications controller accepts commands at data

rates from 1200 to 115,200 bps. The default serial data

rate is 9600 bps and can be changed using register S23.

The communications controller uses the AT command

prefix to automatically determine the parity of the

incoming characters.

Command Prefix - Each command, except the A/

command, begins with the AT prefix. The "A" and "T"

may be either both upper case or both lower case but

cannot be of different cases. The prefix identifies parity of

the commands sent to the XE900SL10 by comparing the

parity bits of the "A" and the "T" characters.

Command Line - Commands may be strung together in a

single command line of up to 30 characters. Commands in

the command string are executed in the sequence they

appear.

Omitted Parameters - Most commands include a

parameter which determines the function setting. When

the command parameter is omitted from the command

string, it is assumed to be a 0.

Result Codes - A result code is normally issued after each

action. Result codes may be provided as full words, one

or two digit numeric codes, or may be disabled all

together. Each result code ends with a carriage return

when numeric result codes are chosen. When full word

result codes are chosen, a Line Feed and Carriage Return

precede and follow each result code.

Disconnect Sequence - A three character sequence

initiates a disconnect of the wireless link. The sequence

“~~~” is assigned to disconnect the link.

DIRECT CONNECTION OF SENSORS:

SensorOnAir™

Sensors can be connected directly to the XE900SL10

without requiring an applications controller. In this

SensorOnAir™ configuration the XE900SL10

communications controller controls the operation of the

sensors.

Sensor I/O Lines

SensorOnAir controls the operation of 6 I/O lines to the

XE900SL10. This includes 2 analog inputs, ADC0 and

ADC1, and 4 digital I/O lines, DIO0, DIO1, DIO2, and DIO3.

ADC0 and ADC1 are connected to a 12-bit analog to digital

converter and using a 2.5 volt reference derived from VCC

as their reference voltage. The digital I/O lines can be

programmed to act as either inputs or outputs.

XECOM

(8)

XE900SL10

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