Appearance
AT Command Introduction
1. AT Command Character
AT command characters are shown as follows.
| Character | Name | Function |
|---|---|---|
| <CR> | Carriage return character | End a command line and is issued together with <LF>. Hexadecimal format: 0x0D. |
| <LF> | Line feed character | End a command line and is issued together with <CR>. Hexadecimal format: 0x0A. |
| <…> | Angle brackets | Parameter name; Angle brackets <> do not appear on the command line. |
| […] | Square brackets | Optional parameter; Square brackets [ ] do not appear on the command line. |
| __ | Underline | Default setting of a parameter. |
2. AT Command Type
All command lines must start with AT or at . AT commands are divided into four types: Test Command, Read Command, Write Command, Execution Command , as shown in the following table.
| Command Type | Syntax | Description |
|---|---|---|
| Test Command | AT+ < CMD > =? | Test the existence of corresponding Write Command and return information about the type, value, or range of its parameter. |
| Read Command | AT+ < CMD >? | Check the current parameter value of a corresponding Write Command. |
| Write Command | AT+ < CMD >=p1[,p2[,p3[…]]] | Set user-definable parameter value. |
| Execution Command | AT+ < CMD > | Return a specific information parameter or perform a specific action. |
3. AT Command Syntax
All command lines must start with AT or at. All command lines must end with <CR> . Information responses and result codes always start and end with a carriage return character and a line feed character: <CR><LF><response><CR><LF> . In tables presenting commands and responses throughout this document, only the commands and responses are presented, and <CR> and <LF> are deliberately omitted.