Monday, November 4, 2024

All You Wanted To Know About AT And GSM AT Commands

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GSM AT COMMANDS

What are AT commands?

AT commands are commands which are used to control the modems where AT stands for Attention. These commands were derived from Hayes commands which were used by the Hayes smart modems. Every wireless, as well as the dial up modems, require an AT command to interact with a computer machine. These AT commands along with other extended commands also require Hayes command set as a subset.

Usage

The AT commands can be used with GSM module and GPRS MODEMs or phone to access these services and information:

  • SMS
  • MMS
  • Fax
  • Voice link and other data over mobile network
  • Information and configuration concerning the mobile devices or MODEM and SIM card.

Types of AT Command

There are 4 basic types of AT command:

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1. Test: The test command is utilised to check the compatibility of a command by a modem.

    SYNTAX: AT=?

    2. Read: Read command is used for extracting the mobile or modem settings required for operations.

    SYNTAX: AT?

    3. Set: This commands is used to make changes into mobile phone or modem settings required for the operation.

    SYNTAX: AT=value1, value2, …, valueN

    4. Execution: As the name suggests, this command is used to execute the said operation.

    SYNTAX: AT=parameter1, parameter2, …, parameterN

    Most Commonly Used AT Commands

    The below 7 are the most commonly used AT commands:

    1. AT: Used to check the interaction between the computer and the module. This command is usually replied with an OK if the port and the module can connect correctly, else wise it comes back with a result code ERROR.

      2. +CMGF: Used to setup the SMS mode. By adding 1 or 0 with the command text or PDU mode can be selected. Here the text mode is easy to operate although it only allows a few limited features of SMS. Where as the PDU mode allows a more detailed access to the SMS service, although to use this you require some basic knowledge of TDPU.

      SYNTAX: AT+CMGF=<mode>

      3. +CMGS: Used to send SMS to a particular phone number

      SYNTAX: AT+CMGS= serial number of message to be send.

      4. ATD: Used to make call to a particular number

      SYNTAX: ATD;(Enter)

      5. ATA: Used to answer the incoming calls. The calls are denoted by a message ‘RING’ which duplicated for every ring of the call. After the call ends a message saying ‘NO CARRIER’ is displayed.

      SYNTAX: ATA(Enter)

      6. +CMGW: Used to store a message in the SIM. After the execution of the command, the ‘>’ sign appears in the next line where the message can be entered.

      SYNTAX: AT+CMGW=” Phone number”> Message to be stored Ctrl+z

      7. ATH: This command is utilized to disconnect a remote user with the GSM module.

      SYNTAX: ATH (Enter)

      List of AT Commands

      Testing:
      CommandDescription
      ATChecking communication between the module and computer.
      Call control:
      CommandDescription
      ATAAnswer command
      ATDDial command
      ATHHang up call
      ATLMonitor speaker loudness
      ATMMonitor speaker mode
      ATOGo on-line
      ATPSet pulse dial as default
      ATTSet tone dial as default
      AT+CSTASelect type of address
      AT+CRCCellular result codes
      Data card Control:
      CommandDescription
      ATIIdentification
      ATSSelect an S-register
      ATZRecall stored profile
      AT&FRestore factory settings
      AT&VView active configuration
      AT&WStore parameters in given profile
      AT&YSelect Set as power up option
      AT+CLCKFacility lock command
      AT+COLPConnected line identification presentation
      AT+GCAPRequest complete capabilities list
      AT+GMIRequest manufacturer identification
      AT+GMMRequest model identification
      AT+GMRRequest revision identification
      AT+GSNRequest product serial number identification (IMEI)
      Phone control:
      CommandDescription
      AT+CBCBattery charge
      AT+CGMIRequest manufacturer identification
      AT+CGMMRequest model identification
      AT+CGMRRequest revision identification
      AT+CGSNRequest product serial number identification
      AT+CMEEReport mobile equipment error
      AT+CPASPhone activity status
      AT+CPBFFind phone book entries
      AT+CPBRRead phone book entry
      AT+CPBSSelect phone book memory storage
      AT+CPBWWrite phone book entry
      AT+CSCSSelect TE character set
      AT+CSQSignal quality
      Computer data interface:
      CommandDescription
      ATECommand Echo
      ATQResult code suppression
      ATVDefine response format
      ATXResponse range selection
      AT&CDefine DCD usage
      AT&DDefine DTR usage
      AT&KSelect flow control
      AT&QDefine communications mode option
      AT&SDefine DSR option
      AT+ICFDTE-DCE character framing
      AT+IFCDTE-DCE Local flow control
      AT+IPRFixed DTE rate
      Service:
      CommandDescription
      AT+CLIPCalling line identification presentation
      AT+CRService reporting control
      AT+DRData compression reporting
      AT+ILRRDTE-DCE local rate reporting
      Network Communication parameter:
      CommandDescription
      ATBCommunications standard option
      AT+CBSTSelect bearer service type
      AT+CEERExtended error report
      AT+CRLPRadio link protocol
      AT+DSData compression
      Miscellaneous:
      CommandDescription
      A/Re-execute command line
      AT?Command help
      AT*CStart SMS interpreter
      AT*TEnter SMS block mode protocol
      AT*VActivate V.25bis mode
      AT*NOKIATESTTest command
      AT+CESPEnter SMS block mode protocol
      SMS Text mode:
      CommandDescription
      AT+CSMSSelect message service
      AT+CPMSPreferred message storage
      AT+CMGFMessage format
      AT+CSCAService centre address
      AT+CSMPSet text mode parameters
      AT+CSDHShow text mode parameters
      AT+CSCBSelect cell broadcast message types
      AT+CSASSave settings
      AT+CRESRestore settings
      AT+CNMINew message indications to TE
      AT+CMGLList messages
      AT+CMGRRead message
      AT+CMGSSend message
      AT+CMSSSend message from storage
      AT+CMGWWrite message to memory
      AT+CMGDDelete message
      SMS PDU mode:
      CommandDescription
      AT+CMGLList Messages
      AT+CMGRRead message
      AT+CMGSSend message
      AT+CMGWWrite message to memory

      This article was first published on 26 Dec 2013 and was recently updated on 24 October 2024.

      8 COMMENTS

      1. How can I increase my bandwidth in end to end communication by mobile please.
        I already built 2 cryptosystem and my problem is bandwidth of two handset mobiles which is not enough bandwidth between operator and mobile side.

        Thanks in advance

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