Java At Commands

AT Commands

R4R provide basic AT Commands Tutorials concept withAT Commands Examples .Through R4R you can develop AT Commands programming concept. R4R provideAT Commands Interview Questions with answers.R4R provide AT Commands Languages study materials in easy way.

AT-COMMAND

AT is the abbreviation of ATtention .AT commands also called Hayes command .At command is used to control modem. The AT command is a Command Prompt command which is used to schedule other commands and programs to run at specific dates and times

WHAT IS MODEM?

MODEMS are used from a long time .The word MODEM is a combination of MODULAR and DEMODULAR. A modem is a device or program that enables a computer to transmit data over, for example, telephone or cable lines.

A MODEM converts data in two forms digital and analog. Computer information is stored digitally whereas information transmitted over telephone lines is transmitted in the form of analog waves. Digital data coming from a DTE, data terminal equipment is modulated in such a way that it can be sent over transmission lines. On the other side another modem demodulates the incoming data and forwards them. Modem keeps everyone connected, over the Internet technology.

TYPES OF MODEM

There are two types of MODEM used

  • Internal modem - These modems are installed inside the PC or Laptop. allowing to communicate with other computer over the network. internal modems are further divided into two categories. Dial-up and WI-FI (wireless) internal modems also called built in modems or PC card modem.

    Internal computer modems are used with Dial-Up Internet connection through a couple of RJ-11 connection. Also called copper telephone lines, the RJ-11 allows computer to receive and send data Internal computer modemsare usually 56K modems which mean that the modem is able to receive 56 Kbps (56 kilobits or 56000 bits per second) of data

  • External modem- External modem is a small box that can used other interfaces to connect to the computer. The purpose of external modem is same as internal modem. serial modem is one of the external modem it called serial because it uses serial port to connect to the computer.other external modem is USB modem which is also a small box it connect to the USB port.

    Another type of external modem that may consider two important types of modem: cable modem and DSL modem. Cable modems is a type of modem that allows people to access the Internet via their television service. DSL (Digital Subscriber Line) modem is used for connections from a telephone switching office to the user. DSL modem is a device used to connect a single computer or router to a DSL phone line. service. Another example of external modem is GSM modem. A GSM modem can be an external unit . An external GSM modem is connected to a PC through a serial cable, a USB cable, Bluetooth or Infrared. Like a GSM mobile phone, a GSM modem requires a SIM card from a wireless carrier in order to operate. PC use AT command to control modem.

  • WHY USE AT-command?

    AT command are instructions used to control modem. Every command line on command prompt for modem start with "AT" or "at "command.therefore modem commands are called AT commands. There are two type of AT command.

  • Basic command - Basic AT commands are those commands which are not started with "+".sign.for example D (dial) , A (answer) ,H (hook), and O (return to the online data state) are basic AT commands.
  • Extended commands - These commands are start with "+" sign.all GSM AT commands are extended commandsSome commands that are used to control wired dial-up modems are:

    For example +CMGS (Send SMS message), +CMSS (Send SMS message from storage), +CMGL (List SMS messages) and +CMGR (Read SMS messages) are extended commands.

  • GENERAL SYNTAX OF AT COMMAND

    Here are some of the tasks that can be done using AT commands with a GSM/GPRS modem or mobile phone: Commands to get the basic information about the mobile phone or GSM/GPRS modem

  • AT+CGMI used to the name of the manufacturer
  • AT+CGMM used to get the model number.
  • AT+CGSN to get the IMEI (international mobile equipment identity) number of equipment.
  • AT+CGMR to get the software version 2.Commands to get the basic information about the subscriber.
  • (AT+CIMI). to get IMSI number (International Mobile Subscriber Identity)3. To get the current status of the mobile phone or GSM/GPRS modem.
  • (AT+CPAS) to know the mobile phone activity status.
  • (AT+CREG to know the mobile phone registration status.
  • (AT+CSQ) to know the radio signal strength.4.At command to send and receive fax Send and receive fax
  • (ATD, ATA, AT+F*).At command to read ,write ,search phone book.
  • Read (AT+CPBR), write (AT+CPBW), or search (AT+CPBF) phonebook entries. AT command to Save and restore configurations of the mobile phone or GSM/GPRS modem. save (AT+CSAS) and restore (AT+CRES) settings related to SMS messaging such as the SMS center address

    At-Commands Tutorials
    At-Commands Examples
    At-Commands Interview Questions with Answers