AT Command datasheet pdf EM770W MI download Huawei WCDMA wireless module

Huaei EM770W MI Datacard AT command v2.2.pdf

HUAWEI UMTS Datacard/Modem AT
Command Interface Specification

1 Scope
This document describes the AT interface of Huawei UMTS Datacard/Modem. The
description on the AT interface is only limited to the interface packet itself, the usage
and use procedure of TE and MS, and does not cover the contents which are not
directly related to the interface.
1.1 Interface Overview
HUAWEI UMTS Datacard/Modem is a wireless terminal of the PCMCIA or Express or
USB interface. It is used together with PC to provide data service, voice and SMS
functions.
This document describes the AT interface. Therewith no description or definition
explain for the document interface, and no temporary support to all kinds of parameter
values, so no suggestion of usage.
In the subsequent AT command parameters, two formats are involved: <>, and [], as
described below:
<...> Parameters enclosed in angle brackets must be completed. Brackets
themselves do not appear in the command line.
[...] Optional subparameter of a command is enclosed in square brackets.
Brackets themselves do not appear in the command line or response.
<CR> Carriage return character, which value is specified with command S3.
<LF> Linefeed character, which value is specified with command S4.

1.2 Interface Design Principles
1) Each interface should be functionally convergent.
2) Since the AT command is a packet transmitted via communication port, the packet
size is limited. For the transmission of AT command, in addition to the two characters
“AT”, a maximum of 260 characters can be received (including the empty characters
at the end). For the “response” message or URC reported by the board, the maximum
length is limited to 668 characters.

3) Each command line can include only one AT command. For the URC instruction or
response reported from MS to TE, only one AT command is allowed in a command
line.
4) In order to make the commands and response formats more readable and
standard, except the original interfaces of Qualcomm, in all newly added interfaces,
e.g. no space can be contained in the commands such as AT^XXX: <arg0>, <arg1>, or
behind ^, colon or comma. No redundant space is allowed at the head or end.
5) After delivering each AT command, the TE cannot deliver the second AT
command until the MS has made response to this AT command. Otherwise, the
second AT command will not be executed.
6) For the AT command to which the response is given only after a long time, in order
to prevent interference on other events, it is recommended to report the final execution
result asynchronously. If the MS responds to the TE only after a long time of waiting,
e.g. the “AT+CCFC=?” command receives a response only after a long time after the
command is delivered, the MS may have received the reported instruction of RING on
this occasion. Namely, the reporting of RING may interrupt other responses, and other
URCs will not interrupt the response of command, and the interrupted part of the
response will continue being reported.
7) Unless otherwise specified, all default codes between TE and MS take on this
format: GSM 7 bit Default Alphabet. See also Section 6 in protocol 23.038. The
character @ is transmitted on the interface still according to 0x00 of 7bit coding. The
board software and API should be able to process this character. The board uploads
the carriage return character (<CR>) and linefeed character (<LF>) in the string in the
form of space.
8) a sort of compounding between quotation and comma can not exist in the string in
this current version. For the data format of UCS2 code, the code value should be
reported in the string format (if the code value is 0x553a, 553a should be reported).
9) The “Possible response” sent from MS to TE is composed of “Information text”
and “Result code”, where “Information text” is optional, and “Result code” is mandatory.
The format of “Possible response” is controlled by the ATV command, as detailed in
the ATV command description. All “Possible responses” listed in the tables in this
documents are in the ATV1 format.

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