FreeRTOS+CLI is an extensible framework that allows the application writer
to define and register their own command line input commands. Functions that implement the
behaviour of a user defined command have to use a particular interface, which is described
on a separate page.
This page describes FreeRTOS_CLIRegisterCommand(), which is the
API function used to register commands with FreeRTOS+CLI. A command is
registered by associating the function that implements the command behaviour with
a text string, and telling FreeRTOS+CLI about the association.
FreeRTOS+CLI will then automatically run the function each time the command text string
is entered. This will become clear after reading this page.
Note: The FreeRTOS_CLIRegisterCommand() prototype that appears in the code take a const pointer
to a const structure of type CLI_Command_Definition_t. The const qualifiers
have been removed here to make the prototype easier to read.
The command being registered, which is defined by a
structure of type CLI_Command_Definition_t. The structure is described
below this table.
pdPASS is returned if the command was successfully registered.
pdFAIL is returned if the command could not be registered because there
was insufficient FreeRTOS heap
available for a new list item to be created.
Commands are defined by a structure of type CLI_Command_Definition_t.
The structure is shown below. The comments in the code describe the
typedef struct xCLI_COMMAND_DEFINITION
/* The command line input string. This is the string that the user enters
to run the command. For example, the FreeRTOS+CLI help function uses the
string "help". If a user types "help" the help command executes. */
const int8_t * const pcCommand;
/* A string that describes the command, and its expected parameters. This
is the string that is output when the help command is executed. The string
must start with the command itself, and end with "\r\n". For example, the
help string for the help command itself is:
"help: Returns a list of all the commands\r\n" */
const int8_t * const pcHelpString;
/* A pointer to the function that implements the command behaviour
(effectively the function name). */
const pdCOMMAND_LINE_CALLBACK pxCommandInterpreter;
/* The number of parameters required by the command. FreeRTOS+CLI will only
execute the command if the number of parameters entered on the command line
matches this number. */
The CLI_Command_Definition_t structure
One of the FreeRTOS+CLI featured demos implements a file system
"del" command. The command definition is given below.
static const CLI_Command_Definition_t xDelCommand =
"del <filename>: Deletes <filename> from the disk\r\n",
The definition of the file system del command
Once this command is registered:
prvDelCommand() is executed each time the user types "del".
"del <filename>: Deletes <filename> from the disk\r\n" is output to
describe the del command when the user types "help".
The del command expects one parameter (the name of the file being
deleted). FreeRTOS+CLI will output an error string instead of executing
prvDelCommand() if the number of input parameters is not exactly 1.
The del command is then registered with FreeRTOS+CLI using the following function call:
FreeRTOS_CLIRegisterCommand( &xDelCommand );
Registering the xDelCommand structure with FreeRTOS+CLI