AT Command Parser Library

AT command parser is a library which helps application developers to quickly connect to Cloud via MQTT using AT commands.

Overview

The AT command parser library provides APIs to intialize the AT command parser library and to register the AT Command table. The AT command library parses string-based AT commands from the UART. The library verifies that the command is a valid command in the correct format and then processes all of the common fields. The Command_Name field is extracted and compared against the command tables that have been registered with the library via API at_cmd_parser_register_commands(), when a match is found, the associated callback routine is invoked parse the message arguments. The callback routine creates a command message and returns that to the library to be passed to the application for processing.

The library provide APIs for

Library initialization
Registering a command table
Sending response and asynchronous messages

AT Command format

AT+XXXX#;Command_Name[,JSON_Text];\n

XXXX: Four-digit length indicating the number of bytes in the command. Count denotes the number of characters between the semicolons.
#: Serial number of the command. Serial number may be a variable number of digits.
Command_Name: The command name from the registered command table.
JSON_Text: Command specific JSON text with any arguments for the command. The JSON test is parsed by the command callback function.

NOTE: If XXXX command length is zero then the command length will be end of carriage return/line feed.

Successful Response

+SXXXX,#;0[,JSON_Text];\n

XXXX: Four-digit length indicating the number of bytes in the response message. Count denotes the number of characters between the semicolons.
#: Serial number that is given by host in AT command.
JSON_Text: Optional command specific response information.

Error Response

+SXXXX,#;NN[,Error_Message];\n

XXXX: Four-digit length indicating the number of bytes in the response message. Count denotes the number of characters between the semicolons.
#: Serial number that is given by host in AT command.
NN: Non-zero error number returned for command.
Error_Message: Optional error message string.

Asynchronous Message

Some commands may initiate actions which cause later messages to be generated. For example, starting a scan and the subsequent scan results.

+HXXXX,#;Message_Name,JSON_Text;\n

XXXX: Four-digit length indicating the number of bytes in the response message. Count denotes the number of characters between the semicolons.
#: Serial number of the AT command which caused this message to be generated.
Message_Name: String name of the message. For example: 'ScanResult'
JSON_Text: Message specific response information.

Supported platforms

CYW955913EVK-01 Wi-Fi Bluetooth® prototyping kit

More information

For more information, refer to the following documents:

at-command-parser/README.md