Overview of AT instruction set

AT is to noTE thAT at instruction set is sent from terminal equipment (te) or data terminal equipment (DTE) to terminal adapter (ta) or data circuit terminal equipment (DCE). AT commands are sent by TA and TE to control the functions of mobile station (MS) and interact with GSM network services. Users can control calls, short messages, phone books, data services, faxes, etc. through AT commands.

In the early 1990s, the AT instruction was only used for modem operation. There is no precedent for controlling SMS, only a protocol called SMS BlockMode has been developed, and SMS is completely controlled by terminal equipment (TE) or computer. A few years later, the major mobile phone manufacturers Nokia, Ericsson, Motorola and Hewlett-Packard * * * developed a set of AT instructions for GSM, including the control of short messages. On this basis, the AT instruction evolved and was added to the GSM07.05 standard and GSM07.07 standard, which is a completely standardized and relatively sound standard. For example, there are three ways to control SMS: initial BlockMode；; TextMode is based on AT instruction; PDUMode based on AT instruction. To PDUMode has replaced BlockMode and gradually faded out. The communication protocol between GSM module and computer is some AT instruction sets. The AT instruction is a string thAT starts with AT and ends with a character, and the response packet of the at instruction is in. Whether each instruction is executed successfully or not will be rewarded accordingly. For other unexpected information (such as someone dialing in, no signal on the line, etc.) ), the module will have some corresponding information prompts, and the receiving end can do corresponding processing.

Example: CDMA modem DTE

AT & ltCR & gt

& ltLF & gtOK & ltLF & gt

Prove & ltCR & gt

& ltCR & gt error & ltLF & gt

If the AT instruction is executed successfully, the "OK" string is returned;

If the syntax of the AT instruction is wrong or the execution of the AT instruction fails,

Error string returned.