The AT Command
Description of Commands
Check if serial interface and GSM modem is working.
Turn echo off, less traffic on serial line.
Display of new incoming SMS.
Selection of SMS memory.
SMS string format, how they are compressed.
Read new message from a given memory location.
Send message to a given recipient.
Download software/ code written for microcontroller 8051 to interface SMS Based Controlling Machines Using GSM Mobile and
, the AT89S52 is designed with static logic for operation down to zero frequency and supports two software selectable power saving modes. The Idle Mode stops the CPU while allowing the RAM, timer/counters, serial port, and interrupt system to continue functioning. The Power-down mode saves the RAM con-tents but freezes the oscillator, disabling all other chip functions until the next interrupt. In this project MODEM is communication with the microcontroller through serial port, the microcontroller will send the commands to the modem through RS 232.and the data is read through serial port therefore to make compatible computer serial port with microcontroller serial port we are using the RS 232 converter.A GSM network is composed of several functional entities, whose functions and interfaces are specified. Figure 1 shows the layout of a generic GSM network. The GSM network can be divided into three broad parts. The Mobile Station is carried by the subscriber. The Base Station Subsystem controls the radio link with the Mobile Station. The Network Subsystem, the main part of which is the Mobile services Switching Center (MSC), performs the switching of calls between the mobile users, and between mobile and fixed network users. The MSC also handles the mobility management operations. Not shown is the Operations and Maintenance Center, which oversees the proper operation and setup of the network. The Mobile Station and the Base Station Subsystem communicate across the Um interface, also known as the air interface or radio link. 8051 provides a transmit channel and a receive channel of serial communication. The transmit data pin (TXD) is specified at P3.1, and the receive data pin (RXD) is at P3.0. All modes are controlled through SCON, the Serial control register. The timers are controlled using TMOD, the Timer mode register, and TCON, the Timer control register. free circuit electronic gsm controller system ,controlling machines using gsm mobile sms services gsm interfacing with microcontroller 8051